Doctoral Degrees (Animal and Poultry Science)

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A description of the chemical and physical growth of New Zealand white and chinchilla rabbits.
(2024) Eniwaiye, Adenike Adetutu.; Rani-Kamwendo, Zikhona Theodora.
This study investigates two key aspects in animal science: (i) describing the growth potential and chemical composition of two commercially bred rabbit strains, in order to optimize the composition of their feed based on variables predicted by simulation modelling; (ii) testing the hypothesis that the allometric relationship between body parts remains consistent across different strains, sexes, and body protein levels. In other words, the research assesses whether animal scientists have faced challenges in modifying the proportional relationship between the weight of different body parts of rabbits and their body protein weight. The primary goal of the study was to outline the physical and chemical transformations in the body composition of two commercially bred rabbit breeds, namely New Zealand White and Chinchilla, over a 126-day growth period. The key focus was on investigating how the growth performance of developing rabbits is affected by sex and age, considering the influence of body protein. Moreover, the research examined alterations in growth and variations in the physical and chemical elements of the body. To achieve the objectives, series of studies were conducted: In this experiment, a total of 220 rabbits, consisting of both New Zealand White and Chinchilla strains, were utilized. Weekly weighing of 100 rabbits from each strain were conducted, starting from day 14 (due to the fragility of the kittens at birth) and continuing until day 140, in order to assess the growth potential of each rabbit. Additionally, samples were collected from 120 rabbits from each strain at specific ages: day 14, 21, 28, 35, 42, 56, 70, 84, 112, and 140. Before slaughter, the animals underwent weighing to determine their weight exclusive of internal organs. Post-slaughter, their weight was measured again to discern the weightof internal organs, skin, and the weight without the skin. The dissected body parts were weighed, labeled, and stored in a freezer for subsequent thawing and mincing. The specimens were then subjected to freeze-drying to extract water content. Following this, they underwent further grinding before being analyzed for protein, lipid, and ash. Moreover, the Gompertz equation was applied to individual body parts and the protein weight of each body component. The parameters of the Gompertz equations were defined as the final weight of these components, their rate of maturation, and the time required to achieve the peak growth rate of each component. By utilizing data from each individual rabbit, allometric regressions were employed to establish the relationship between the weights of physical and chemical components. The natural logarithm of body protein weight served as the independent variable, while the natural logarithm of body component weight served as the dependent variable. A significant allometric relationship was found between body weight and pelt weight, as the weight growth process occurs continuously from birth to maturity. Body weights and chemical composition of males and females (bucks and does) of the two strains remained similar throughout the trial. Mature body weights for both strains (New Zealand White and Chinchilla) at 140 days averaged 1760 g and 1558 g; mature body protein weights averaged 95 g/kg and 61 g/kg; and mature body lipid contents averaged 40 g/kg and 55 g/kg, respectively. Rates of maturing per day of body weights for males and females of both strains averaged 0.0241 and 0.251; pelt-free, 0.0294 and 0.0251, and body lipid was 0.0441 and 0.0225, respectively. The rates for body protein differed between New Zealand White females and Chinchilla females (0.0172 vs 0.0256/d). Separate equations were needed for males and females to describe the allometric relationships between lipid and protein in the pelt-free body. The rate of maturing of pelt in the New Zealand White was higher in females than in males (0.0249 vs 0.0214/d), and the mature weight was lower in females than in males (45vs 52 g/kg), respectively. Common values of the sexes for both strains are represented when there were no apparent variations in the constant terms and regression coefficients. The saddle weights, regardless of the protein content in both sexes of the New Zealand White, can be described by a single constant term of 1.0193, and a lower single constant term value of -1.1070 in the Chinchilla rabbit. The goodness of fit (R2) for both strains was highest in the saddle with 0.974 and 0.957 in the New Zealand White and Chinchilla gigantas rabbits, respectively, while it was lowest (0.922) in the pelt of New Zealand White and hindlimb (0.892) of the Chinchilla gigantas rabbits. Sexes differed in the allometric relationships of all component parts measured in both breeds. A common relationship between the two strains could be used to predict the weights of all rabbit major component parts. Further studies are recommended to confirm the findings of this study. Keywords: Chemical, Chinchilla, Components, Physical, New Zealand white, Rabbits.
Response in growth performance, carcass traits, fatty acid profiles and health indices of pork from windsnyer pigs supplemented with amarula oil cake.
(2023) Thabethe, Fortune.; Chimonyo, Michael.
To conserve the slow-growing Windsnyer pigs, it is crucial to explore their efficiency in utilising locally available ingredients such as Amarula oil cake (AOC). The use of Amarula oil cake in pig diets can ease the pressure of relying on conventional feed sources and broaden the feed resource base for pigs. The broad objective of the study was to assess the relationship between feeding increasing levels of Amarula oil cake on the growth performance of Windsnyer pigs and selected pork quality traits. Twentyfive clinically healthy intact growing boars with an initial body weight of 19.9 ± 8.74 kg were used in the study which lasted for six weeks excluding the adaptation period of one week. Pigs were assigned to five experimental diets in a completely randomised design and diets were formulated to contain 0, 50, 100, 150, and 200 g/kg DM of AOC. The average daily feed intake (ADFI), average daily gain (ADG), feed conversion ratio (FCR), scaled average daily feed intake (SADFI), scaled average daily gain (SADG), and body weight (BW) were calculated weekly. The diet affected ADFI, ADG, FCR, and SADG (P < 0.05). The scaled average daily feed intake was not affected by the diet (P > 0.05). There was a significant interaction between AOC inclusion and weeks of feeding on ADFI, ADG, and FCR (P < 0.05). A positive quadratic relationship between ADFI and increasing levels of AOC was observed (P < 0.05). Average daily gain, FCR, and SADG decreased linearly with increasing AOC levels (P < 0.05). Using the broken stick analyses, the maximum inclusion level of AOC was obtained at 102.17 g/kg DM with an optimum ADFI of 1.25 kg/day. Amarula oil cake can be incorporated in Windsnyer pig diets up to 100 g/kg DM without constraining growth performance of Windsnyer pigs. v The specific objective for experiment two was to determine the relationship between incremental levels of AOC, carcass characteristics, primal pork cuts, and visceral organ weights of South African Windsnyer pigs. There was a negative linear relationship between increasing AOC levels, carcass length, warm carcass weight, and cold carcass weight (P < 0.05). Stomach weight, backfat thickness, drip loss, and the hepatosomatic index increased linearly with increasing AOC levels (P < 0.05). The kidneys, small intestines, and large intestines weight of Windsnyer pigs had a quadratic response to AOC inclusion level (P < 0.05). The heart, lungs, and spleen were not related to increasing levels of Amarula oil cake inclusion (P > 0.05). Incremental AOC diets impaired carcass characteristics and the selected visceral organs of pigs. Windsnyer pigs can, therefore, be fed Amarula oil cake up to 100 g/kg dry matter. The specific objective for experiment three was to assess the changes in nutritionally related metabolites and liver enzymes of Windsnyer pigs fed on increasing levels of AOC based diets. After subjecting the pigs to six weeks of feeding on the experimental diets, blood samples were collected. Serum was analysed for total protein (TP), albumin, globulin (G) iron, Uric acid (UA), albumin: globulin ratio (A: G), alkaline phosphatases (ALP), aspartate aminotransferase (AST), aminotransferase (ALT). The albumin concentration of pigs linearly decreased with incremental levels of AOC (P < 0.05). The concentration of TP and G decreased quadratically with incremental levels of AOC (P < 0.05). On the other hand, ALP increased quadratically with increasing levels of AOC (P < 0.05). The other blood metabolites and liver enzymes were not related to the inclusion level of AOC (P > 0.05). The specific objective for experiment four was to determine the relation between fatty acid composition and health lipid indices of pork from Windsnyer pigs supplemented with different AOC levels. Increasing AOC inclusion levels, linearly increased C12:0, C14:1n9c, C18:1n9t and C18:3n6 of pork from Windsnyer pigs (P < 0.05). Increasing AOC levels linearly decreased SFA, PUFA/SFA ratio, C18:1n11c and C20:3n3 of pork from Windsnyer pigs (P < 0.05). There was a quadratic decrease in n-3 fatty acids, n- 6/n-3 ratio, nutritive value, C22:0, C18:1n9c, C18:3n3, C18:2c911t, C20:4n6 and C22:5n3 of pork (P < 0.05). The total MUFA, PUFA, n-6 fatty acids, AI and TI were not related to AOC inclusion (P > 0.05). Due to the quadratic relation of n-3 PUFA, n-6/n- 3 ratio of FA and nutritional value of pork, it is recommended that AOC based diets be fed up to 150 g/kg DM. Low levels of AOC of up to 100 g/kg DM improved growth performance, nutritionally related metabolites, carcass traits of pigs. High inclusion levels of AOC improved fatty composition of pork from Windsnyer pigs. Key words: Body weight gain; carcass length: dietary fibres; feed intake; hepatosomatic index; organ weight; total protein; polyunsaturated fatty acids; saturated fatty acids.
A model of calcium and phosphorus growth in broilers.
(2022) Salisbury, Frances.; Gous, Robert Mervyn.
A model is a simplified representation of a system. It can be used to organise knowledge and to develop theory in an academic setting, but also for practical applications. This research sought to incorporate as much as possible of the theory of calcium and phosphorus in broiler chickens into a model. This would allow researchers to see where there are gaps in the theory and to suggest ways in which experiments might be designed to fill these. It is hoped that this model will provide a guide for producers when they feed broilers, particularly under changing conditions. Current tables of requirements reflect empirical data on bird performance, collected at a certain point in time. As genetic progress, welfare considerations and environmental pressures change the constraints on an animal production system, a dynamic model allows the nutritionist to be more responsive to these. The calcium/phosphorus model is located within an existing broiler model that simulates energy metabolism and protein growth. This model is linked to a feed formulation component and an optimiser that allows producers to manage their enterprise to meet production and profit targets. Because standardised digestibility values have proved elusive for minerals, a digestibility module assesses the complete feed and calculates mineral quantities available to the bird. These are then assessed against the requirements for soft tissue which is given priority and then bone growth. Excess mineral is excreted and this, and bone mineralisation are considered for the optimiser module of the main model. The model was calibrated and validated using two body composition studies. It was demonstrated that reasonable predictions of performance could be made, but that modelling digestibility is a critical component. Perhaps most importantly, the model maps a way forward for research targeted at filling the gaps in the body of knowledge. These have been shown to be surprisingly large: very little whole carcass body composition work has been done and few studies of calcium and phosphorus digestibility have been designed to allow modelling of their interactions.
Gastrointestinal nematode infestation, goat performance and nutritionally-related blood metabolites of Xhosa lop-eared does foraging in grasslands and forestland vegetation types = Ukuqubuka kwe-gastrointestinal nematode, ukuhamba kwebhizinisi lezimbuzi namamethabholaythi asegazini ahlobene nokondleka kwezimbuzi ezingama-Xhosa lop-eared eziklaba ezindaweni ezinotshani obusemadlelweni nasemahlathini.
(2022) Qokweni, Luxolo.; Chimonyo, Michael.; Marufu, Munyaradzi Christopher.
The broad objective of the current study was to determine gastrointestinal nematode infestation (GIN), goat performance and nutritional status of Xhosa lop-eared does foraging in grassland relative to those browsing in forestland vegetation types. A cross-section survey was conducted to 282 goat farmers from Mbizana Local Municipality in Alfred Nzo district, South Africa to investigate perceptions on the control of GIN infestation. Data collected included household demography, goat health and parasites, goat feeding and management. Variation in the prevalence of gastrointestinal parasites and their effect on growth performance in 309 Xhosa lop-eared goats with an average age of 7 months raised in grassland and forestland vegetation types were determined. In this experiment, 165 indigenous Xhosa lop-eared does were conducted to assess the effect of vegetation type, season and parity on the burden of GIN in Xhosa lop-eared does that were foraging in grassland and forestland vegetation types. Morever, 24 indigenous Xhosa lop63 eared does were used to determine the interaction between vegetation type and season on nutritionally-related blood metabolites, liver enzymes and minerals. Farmers in the grassland vegetation type ranked gastrointestinal parasites as the major constraint to goat productivity than those in the forestland. Farmers in the grassland were more likely to experience gastrointestinal nematode infestation than those in forestland 68 vegetation types (P <0.05). Farmers in the grassland vegetation types were more likely to control gastrointestinal nematode infestation than to those in forestland vegetation type (P < 0.05). Xhosa lop-eared goats in the forestland vegetation type had higher (P < 0.05) body condition score (BCS), body weight (BW) and lower faecal egg count (FEC) compared to those in grassland. Goats with higher (P <0.05) BCS and BW had lower FEC in both vegetation types. The higher higher (P < 0.05) BCS was observed in Xhosa lop-eared does foraging in the forestland vegetation type compared to those in the grassland vegetation type. Xhosa lop-eared does from grassland had higher FEC (P < 0.05) compared to those in forestland vegetation type. In the forestland vegetation type body condition scores and FAMACHA scores were significantly higher during the hot-wet season than cool-dry and post-rainy seasons, while FEC were observed higher in the grassland than forestland vegetation type. Strongyles and Strongyloides eggs were higher in does grazing in the grassland than those in the forestland vegetation type during the hot-wet season. It was concluded that goats are constrained by infestation of gastrointestinal parasites, particularly in the hot-wet season. Poor quality and quantity of forage experienced in the grassland vegetation type can be rectified by feeding goats in forestlands, which can cheaply improve growth performance of goat and health and production in does. Xhosa lop-eared does in the forestland vegetation types had higher (P < 0.05) serum concentration of total protein (TP), globulin, albumin/globulin (A/G) ratio and total bilirubin (TB) during the hot-wet than cool-dry seasons. Total bilirubin concentrations werehigher (P < 0.05) in does in the forestland vegetation type during hot-wet season. The serum concentration of calcium was lower (P < 0.05) during the cool-dry season in both vegetation types. Phosphorus concentrations were higher (P < 0.05) in the grassland vegetation type during the cool-91 dry season than hot-wet season. Albumin/globulin ratio was lower (P < 0.05) in the forestland vegetation type during hot-wet season than cool-dry season. It was concluded that Xhosa lop-eared does are constrained by high prevalence and loads of gastrointestinal nematode infestation, particularly in the grassland vegetation type during hot-wet season. Kids were more susceptible to gastrointestinal nematodes than older goats. The interaction of vegetation type and season should be considered in developing control strategies for gastrointestinal nematodes in Xhosa lop-eared goats. Iqoqa Inhloso ebanzi yalolu cwaningo kwakungukuhlonza i-gastrointestinal nematode infestation (i-GIN), okwenziwa yizimbuzi nomumo wezakhamzimba zama-Xhosa lop-eared okwenziwa utshani emadlelweni nokwenzeka emahlathini. Isaveyi ebifaka zonke izigaba yenziwa kubafuyi bezimbuzi abangama-282 bakuMasipala wasekhaya waseMbizana eSifundeni i-Alfred Nzo, eNingizimu Afrikha ukuphenya izindlelakubuka ukulawula ukuqubuka kwe-GIN. Imininingo eqoqiwe okufaka izinhlobo zabantu abasendlini, impilo yezimbuzi nezimuncigazi, ukondla izimbuzi nokubhekana nalokho. Ukwehlukahlukana kokuvama kwezimuncigazi eziba semathunjini nomthelela wazo ekusebenzeni kokukhula kwezimbuzi ezingama-309 ezingama-Xhosa lop-eared ezinesikhathi esiyizinyanga eziyisi-7 ezikhuliselwe edlelweni nasotshanini zahlonzwa. Kulokhu kuhlola, izimbuzi eziyi-165 zendabuko ezingama-Xhosa lop-eared zahlolwa ngomthelela wohlobo lwezimila, inkathi yonyaka nokulingana komthwalo we-GIN kuzona ezaziklaba emadlelweni nasemahlathini. Ngaphezu kwalokho, izimbuzi zendabuko ezingama-24 ezingama-Xhosa lop-eared zasetshenziswa ukuhlonza ukusebenzelana phakathi kohlobo lwezimila nenkathi yonyaka ezintweni ezihlobene nezakhamzimba ezingamamethabholaythi atholakala egazini, ama-enzayimi esibindi namaminerali. Abalimi abasemadlelweni otshani bathi izimuncigazi ezitholakala emathunjini ziyinkinga enkulu enqinda ukukhiqizeka kwezimbuzi kunalezo ezisemadlelweni asemahlathini. Abalimi abasemadlelweni otshani banethuba elikhulu lokwehlelwa yi-gastrointestinal nematode infestation kunalabo abanamadlelo angamahlathi (i-P < 0.05). Abalimi abasezindaweni ezinamadlelo asemahlathini yibona okubukeka bengakwazi ukulawula i-gastrointestinal nematode infestation kunalabo abanohlobo olwehlukile (i-P < 0.05). Izimbuzi ezingama-Xhosa lop-eared ezihlala endaweni eyidlelo okunezihlahla anezinga eliphezulu lezibalo zesimo somzimba (i-P < 0.05) (i-BCS), isisindo somzimba (i-BW) nezinamaqanda asemasimbeni anesibalo esiphansi (i-FEC) uma kuqhathaniswa nalezo ezisemadlelweni otshani. Izimbuzi ezine-BCS ne-BW ephezulu (i-P < 0.05) zazine-FEC ephansi kuzo zombili izinhlobo zamadlelo. I-BCS ephezulu kakhulu yabonakala ezimbuzini ezingama-Xhosa lop-eared ezazidla ifolishi ezindaweni ezingamahlathi uma kuqhathaniswa nalezo ezidla emadlelweni otshani. Izimbuzi ezingama-Xhosa lop-eared ezazidla emadlelweni otshani zazine-FEC ephezulu (i-P < 0.05) uma kuqhathaniswa nalezi ezidla emahlathini. Izimila lapho kunezihlahla, izibalo zesimo somzimba kanye nezibalo zeFAMACHA zaziphezulu kakhulu kunangesikhathi sokushisa nezimvula kunangesikhathi sokuphola nokoma nangasemuva kwesikhathi sezimvula, ngesikhathi i-FEC ibonakale iphezulu emadlelweni kunasemahlathini. Amaqanda e-strongyles nama-strongyloides ayephezulu kulezo eziklaba emadlelweni kunalezo eziklaba emahlathini ngenkathi yokushisa nobumanzi. Kwaphethwa ngokuthi kuvinjelwe ukuqubuka kwezimuncigazi ama-gastrointestinal parasites ikakhulukazi ngezinkathi zonyaka ezishisayo nezinezimvula ezimbuzini. Ikhwalithi nekhwantithi ebhedayo yokwehla ngenxa yefolishi ezimileni emadlelweni kungalungiseka ngokupha izimbuzi ezindaweni ezinezihlahla, okungaphucula ngendlela engabizi kuphucule ukusebenza kokukhula kwezimbuzi nezimpilo zazo kanye nokukhiqizwa kwazo. Izimbuzi ezingama-Xhosa lop-eared ezindaweni ezinezihlahla (i-P < 0.05) ukunqwabelana kwesiramu yamaphrotheyni aphelele (i-TP), i-globulin, i-albumin/i-globulin (i-A/G) isikalisilinganiso nesamba sebhilirubhini (i-TB) ngesikhathi sokushisa nezimvula ukuna ngesikhathi sokuphola nokoma. Ukunqwabelana kwebhilirubhini okuphelele kwakuphezulu (i-P < 0.05) endaweni enamahlathi ngesikhathi senkathi yokushisa nezimvula. Ukunqwabelana kwesiramu yekhalsiyamu kwakuphansi (i-P < 0.05) ngesikhathi sokuphola nokoma kuzo zombili izinhlobo zezimila. Ukunqwabelana kwefosiforasi kwakuphezulu (i-P < 0.05) endaweni engamadlelo ngesikhathi sokuphola nokoma kunangesikhathi sokushisa nezimvula. Isikalosilinganiso se-albumin/globulin sasiphansi (i-P < 0.05) endaweni enokuxhobelanamahlathi ngesikhathi sokushisa nobumanzi kunangenkathi epholile neyomile. Kwaphethwa ngokuthi izimbuzi ze-Xhosa lop-eared azivinjelwa wukuvama okuphezulu kanye nezinqwaba ze-gastrointestinal nematode infestation, ikakhulukazi ezimileni okusemadlelweni otshani ngesikhathi sokushisa nobumanzi. Amazinyane ayesengcupheni enkulu yama-gastrointestinal nematodes kunasezimbuzini ezindala. Ukusebenzelana kohlobo lwezimila kanye nenkathi yonyaka kumele kubhekwe ekuthuthukiseni imiqondosu yokulawula ama-gastrointestinal nematodes ezimbuzini ezingama-Xhosa lop-eared. Amagama asemqoka: isibalo samaqanda asemasimbeni, izimbuzi zendabuko, izikalo zesimo somzimba, isisindo somzimba, isikalo se-FAMACHA, umthamo weseli egcwele.
Utilisation of indigenous knowledge to mitigate challenges of gastrointestinal nematodes in goats.
(2021) Ndlela, Sithembile Zenith.; Chimonyo, Michael.
Gastrointestinal nematodes (GIN) constitute a huge challenge to goat productivity worldwide, leading to production losses. Anthelmintic drugs have been used to control GIN, but their effectiveness has been reduced due to their high cost, scarcity in resource-limited farms, and drug resistance and residue challenges. Therefore, other sustainable control measures that are cheaper, readily available, and not chemically manufactured, such as indigenous knowledge (IK), are required. The broad objective of this study was to investigate IK methods and practices used to control gastrointestinal parasites in goats. Face-to-face interviews were conducted on IK experts in Jozini Municipality, KwaZulu-Natal, South Africa. Experts used IK because it is part of their culture, locally available and guaranteed to work. Indigenous knowledge was sourced from their forefathers through oral communication and training. Traditional healers had more sources of IK, including visions, dreams and spirits. Experts identified GIN as the most common parasites in goats. They used shape, size and colour in the identification of parasites. Indigenous knowledge was used to identify symptoms caused by GIN infestations. Thirty-three plant species were identified to control worm burdens in goats. A cross-sectional survey was used to determine the extent of IK used to control gastrointestinal parasites in goats. Cissus quadrangularis Linn. was the most widely used plant (67 %), followed by Albizia anthelminthica Brongn. (47 %), Cissus rotundifolia (Forssk.) Vahl (42 %), Vachellia xanthophloea (Benth.) P.J.H. Hurter (38 %), Aloe marlothii A. Berger (38 %), Sclerocarya birrea (A. Rich.) Hochst (36 %), Gomphocarpus physocarpus E. Mey (36 %), Aloe maculata All. (35 %), Trichilia emetica Vahl (33 %), Aloe ferox Mill. (32 %), Vernonia neocorymbosa Hilliard (20 %) and Schkuhria pinnata (Lam) Kuntze ex Thell (16 %). The odds of farmers using IK in the dry environment were 7.9 times more likely than in the wet environment. The likelihood of males influencing the use of IK was twice compared to females (P < 0.01). Adults (> 50 years old) were 1.8 times likely to influence the use of IK than youths (P < 0.05). Farmers residing on-farm were one time likely to use IK (P < 0.05) than those staying outside the farm. The likelihood of having a herbalist in the area was 3.6 times likely to influence the use of IK to control GIN in goats. A structured questionnaire was also used to determine differences in the extent of IK use to control GIN in goats between wet and dry environments. The likelihood of males using IK in the dry environment was eight times (P < 0.01) compared to 1.7 times in the wet environment (P < 0.05). Adults were 1.2 times likely to use IK than youths in the dry environment (P < 0.05), whereas youths used more IK than adults in the wet environment. Unemployed farmers in the dry environment were 4.3 times likely to use IK than employed farmers (P < 0.01). Informally educated farmers used IK more than formally educated farmers in both environments. Farmers who practiced the traditional Zulu culture were 2.1 times more likely to use IK in the dry environment and 1.1 times in the wet environment than those who practiced Christianity (P < 0.05). Farmers who received livestock training were 1.74 times more likely to use IK in a dry environment than the untrained. The presence of herbalists in the dry environment was 3.6 times likely to influence the use of IK (P < 0.01), compared to the likelihood of one time in the wet environments (P < 0.05). Because IK is based on using symptoms to identify goats infested with GIN, relationships between faecal egg count (FEC) and packed cell volume (PCV), body condition score (BCS), and FAMACHA score were determined. A total of 120 Nguni goats made up of weaners, does and bucks were used across all seasons (post-rainy, cool-dry, hot-dry, hot-wet). Higher egg counts were observed in weaners (7406 ± 401.4) and does (4844 ± 401.4) during the hot-wet season, while bucks had the highest counts (5561 ± 529.7) in the cool-dry season. Strongyloides (30 %), Haemonchus contortus (28 %), Trichostrongylus sp. (23 %), Oesophagostomum sp. (17 %), and Ostertagia (2 %) were identified in goats and had higher percentage counts in the hot-wet season. There was no effect of sex on BCS, FAMACHA, PCV and FEC. There was an interaction (P < 0.05) between age and season on FAMACHA score, BCS, PCV and FEC. A lower BCS and PCV were observed in weaners in the cool-dry season. Weaners had higher FAMACHA scores and FEC in the cool-dry season. The rate of change in FAMACHA score was higher in weaners than does and bucks, as FEC increased (P < 0.01). The rate of change in the FAMACHA score was higher in the post-rainy season as FEC increased (P < 0.01) compared to other seasons. There was a linear relationship between FEC and FAMACHA scores. The anthelmintic activity of aqueous extracts of Cissus quadrangularis Linn., Aloe marlothii A. Berger, Albizia anthelmintica Brongn., Cissus rotundifolia (Forssk.) Vahl., Sclerocarya birrea (A. Rich.) Hochst and Vachellia xanthophloea (Benth.) P.J.H. Hurter against GIN was investigated. Each plant was used in two forms: dry and fresh. Three extraction methods were employed, i.e., cold water (infusion), boiled water (decoction) and methanol. Extract concentrations of 8, 16, 24, 32, 40 % v/v were tested in vitro on the mortality of L3 nematodes. There was a linear relationship between larvae mortality and concentration of the boiled fresh form of C. rotundifolia (P < 0.01) extract, cold-water extract of the fresh form of A. marlothii (P < 0.05), cold-water and methanolic extracts of the fresh form of C. quadrangularis (P < 0.01), methanolic extract of the fresh form and cold-water extract of the dry form of V. xanthophloea (P < 0.05), cold-water and methanolic extracts of the dry form of S. birrea (P < 0.0001). Quadratic relationships were observed between larvae mortality and concentration of the fresh form of methanolic extract of C. rotundifolia (P < 0.05), fresh form of methanolic extract of A. anthelmintica (P < 0.01), fresh form of cold and boiled water extracts of V. xanthophloea (P < 0.0001), the fresh form of methanolic extract and the dry form of boiled A. marlothii extract (P < 0.001), fresh form of methanolic extract (P < 0.05) and dry form of boiled S. birrea extract (P < 0.01), and dry form of boiled and methanolic extracts of V. xanthophloea (P < 0.05) plant. Farmers used different plant forms and extraction methods of C. quadrangularis, A. marlothii, A. anthelmintica, C. rotundifolia, S. birrea and V. xanthophloea based on availability and the knowledge they possessed. The effects of most of the plant extracts were not influenced by concentrations, suggesting that lower concentrations could be beneficial for plant preservation and toxicity reduction. However, quadratic relationships observed in other plant extracts suggest that concentrations with high larvae mortality could be adopted. These relationships need to be considered as an integrated approach to achieve sustainable nematode control in goats.
Modelling of feeding behaviour, rumen load and the kinetics of digestion and passage of digesta in domestic and wild ruminants.
(2021) Moyo, Mehluli.; Nsahlai, Ignatius Verla.
Roughage intake is affected by a collection of factors that include feeding behaviour, and the weight of rumen digesta which is a function of digesta clearance from the rumen as governed by the rates of degradation and passage. Accurate prediction of intake depends on the ability to predict these factors. In literature, there are few models, if any, that can be used to estimate the weight of rumen digesta load, simulate feeding behaviour, predict passage rates of solid and liquid digesta, and degradability in the rumen of ruminants inhabiting environments with different diet qualities.The five main objectives of this study were to (1) investigate effects of diet and roughage quality on feeding behaviour; and to determine the main factors affecting and developing Random Forest models to estimate (2) time spent on diurnal feeding behaviours, (3) digestion of feeds in the rumen, (4) weight rumen digesta load and (5) rate of passage of digesta in the rumen. The effects of diet and roughage quality on dry matter intake, duration and number of daytime and night-time eating bouts, and ruminating activities in small ruminants were investigated. In Exp 1 and 2, roughage quality was improved by urea treatment of veld hay, while diet quality was improved by supplementing with Lucerne hay (Exp 3), sunflower meal and lespedeza (Exp 4), fish meal (Exp 5a), and sunflower meal (Exp 5b). Daytime (06:00 to 18:00 h) and night-time (18:00 to 06:00 h) feeding behaviour activities were recorded. Roughage quality affected rumination index in Exp 1, but not in Exp 2, 3, and 5. Time spent eating and ruminating was affected by roughage quality (Exp 1, 3, and 4), period of day (all experiments) and their interaction (Exp 1). Period of day affected the duration of rumination sessions (Exp 1, 2, and 3); diet quality or roughage quality affected the duration of eating bouts (Exp 3) and rumination sessions (Exp 1 and 2). roughage quality had a significant effect on the duration eating sessions in Exp 3 only, whilst period of day affected this same behaviour in Exp 2 and 3. To ascertain the influence of the period of the day, ambient temperature, climatic region, and ruminant feeding type on daytime and night-time feeding behaviour of ruminants a dataset was collected from studies that measured feeding behaviour. Studies that qualified for inclusion into the dataset should have (1) reported times spent eating (TSE), ruminating (TSR) and idling, number and duration of ruminating and eating sessions during a 12h day and 12h night period, and 24 h period (2) measured body weights of animals used, and (3) stated feeds or proportion of feeds in diets fed to or consumed by the animals. Diet properties, animal and environmental factors affecting feeding behaviour were identified in the studies. A mixed effects and regression models captured the influence and response to the period of the day, ambient temperature, climatic region and ruminant feeding type of feeding behaviour. During the day, time spent ruminating and chewing became longer in large ruminants than at night. Predictions showed that time spent eating during the day and at night are expected to decline with an increase in ambient temperature, while times spent ruminating during the day will increase. Grazers and intermediate feeders spent more time eating during the day than at night, while browsers spent more time eating at night than during the day. The influence on 24 h diurnal feeding behaviour patterns of ruminants in response to ambient temperature and ruminant feeding type were ascertained. Feeding behaviours scaled allometrically with body weight for all ruminant feeding types, except for TSE by browsers and intermediate feeders, and TSR by grazers. Times spent eating and TSR become shorter in large compared to small ruminants. Time spent ruminating became shorter in large browsers, while large intermediate feeders spent more TSR than their smaller counterparts. Browsers had less TSE, highest DEB and lowest number of eating bouts compared to grazers and intermediate feeders. Trends from this study showed that TSE, DEB, and idling are projected to increase with ambient temperature, while TSR is likely to decrease. Models to predict TSE and TSR for grazing and browsing ruminants were developed. A dataset was created from studies that reported TSE and TSR, number of eating (NEB) and ruminating bouts (NRB), and the duration of ruminating (DRB) and eating bouts (DEB) over a 24h period. Factors affecting feeding behaviour were identified from each study and grouped into (1) diet properties, (2) animal and (3) environmental factors. These factors were used as input variables for the prediction of feeding behaviour. The dataset was randomly divided into two subsets: 70% for model training and 30% for model testing. Developed models accounted for 95% (TSE), 90% (TSR), 93% (DEB), 93% (DRB), 78% (NEB) and 90% (NRB) of the variation in prediction of feeding behaviour. The models attained 87% (TSE), 62% (TSR), 93% (DEB), 83% (DRB), 82% (NEB) and 77% (NRB) precision in prediction during testing using an independent dataset. This study developed good simulation models for feeding behaviour of ruminants. The consequences of increases in ambient temperature and effect of climate type on digestibility of forages by ruminants using meta-analysis in relation to global warming were evaluated. A dataset on nylon bag degradability parameters bearing the chemical composition of roughages, grains, leaves, stems, fruits, concentrates, and diets given to animals, climate type, and ambient temperature were compiled. Data were analysed using mixed model regression and simple linear regression methodologies. Negative correlations between ambient temperature and degradability parameters were observed. Potential degradability was highest for studies carried out in cold and temperate climates compared to tropical and arid climates. A 1 °C increase in ambient temperature decreased PD by 0.39% (roughages), 0.76% (concentrates), and 2.41% (mixed diets), with an overall decrease of 0.55% for all feed types. The “b” fraction decreased by 0.1% (roughages), 1.1% (concentrates), 2.27% (mixed diets), and 0.35% (all feed types) for every 1 °C increase in ambient temperature. Increasing ambient temperature by 1 °C increased the neutral detergent fibre content of feeds by 0.4%. A test of slopes showed that the predicted decrease in rumen digestibility of feeds with ambient temperature would be most severe in tropical and arid regions compared to cold and temperate regions. An evaluation and prediction of the nutritive and feeding value of underutilised forages that have a potential of being ruminant feeds was done. Underutilised forage legumes, leaves/trigs of forage trees and shrubs (non-leguminous), commonly used grass forages and concentrates were collected from various regions. The nylon bag method was used to determine degradability of the underutilised forage legumes, leaves/trigs of forage trees and shrubs (nonleguminous) in the rumen. A step-wise regression procedure was used to develop regression equations to predict degradability of forages in the rumen. Of the underutilised forages, the crude protein content tended to be double for Brassica oleracea var. acephala compared to Colophospermum mopane leaves and pods. Forage grasses (62.9±34 g/kgDM) tended to have very low crude protein contents compared to legumes (137.6±69 g/kgDM) and concentrates (177±39.9 g/kgDM). Underutilised Brassica oleracea var. acephala (305 g/kgDM) tended to have higher crude protein levels compared to commonly used protein sources (cotton seed cake = 222 g/kgDM). The regression model for predicting the soluble fraction accounted for 59% and 71% of the variation in model development and validation of predictions, respectively. The regression model for predicting the potential degradability accounted for 65% and 24% of the variation in model development and validation, respectively. A dataset to enable prediction of degradation parameters in the rumen were collected from studies that (1) reported values for in-sacco degradability parameters viz. soluble fraction (a), slowly degradable fraction (b), potential degradability (PD) and rate of degradation (c) of roughages, grains, leaves, stems, fruits and concentrate formulations, and (2) stated the diets given to animals fed at ad-libitum. Two datasets were collated, one on studies that used the time-lag model and another on studies that used the no-time lag model in computing degradation parameters. Factors that affect degradability were identified in each of these studies and categorised into (i) diet properties (ii) feed sample properties (iii) ruminant feeding type and (iv) environmental factors. These factors were used as input variables to enable prediction of degradability. Each dataset was randomly divided into two subsets: 70% for training and 30% for testing. The no time-lag models attained 88% (“a”), 93% (“b”), 76% (“c”) and 90% (“PD”) precision in prediction during training and 58% (“a”), 52% (“b”), 48% (“c”) and 53% (“PD”) precision in testing. Time lag models accounted for 91% (“a”), 84% (“b”), 79% (“c”), 91% (“PD”) and 87% (lag) of the variation in prediction during training and 64% (“a”), 57% (“b”), 29% (“c”), 52% (“PD”) and 59% (lag) precision in testing. Both sets of models predicted “a”, “b”, PD, and lag with appreciable precision, but models for the prediction of the rate of degradation require improvement. The influence of liquid passage rates on solid digesta passage rates and the possibilities of simultaneous prediction of solid and liquid passage rates in ruminants was examined. Artificial neural networks were used to develop models of solid and solid plus liquid passage rates. Studies that reported fractional passage rates, class and body mass of ruminants were included in the dataset. Factors affecting the rate of passage were identified from each study and grouped into (i) diet properties, (ii) animal, (iii) feed particle properties and (iv) environmental factors. Animal and feed factors that affect the rate of passage were identified in studies and used as input variables to estimate rate of passage in the rumen. The database was composed of observations of domestic and wild ruminants of variable body mass (1.5 to 1238 kg) from 74 (solid using predicted liquid passage rate) and 31 (solid using observed liquid passage rate) studies. Observations were randomly divided into 2 data subsets: 75% for training and 25% for validation. Developed models accounted for 76 and 77% of the variation in prediction of solid passage rates using predicted and observed liquid passage rate as inputs, respectively. Simultaneous prediction accounted for 83 and 89% of the variation of solid and liquid passage rates, respectively. On validation using an independent dataset, these models attained 45% (solid using predicted liquid), 66% (solid using observed liquid), 50% (solid predicted with liquid) and 69% (liquid predicted with solid) of precision in predicting passage rates. Simultaneous prediction of solid and liquid passage rate yielded better predictions (+7%) compared to independent predictions of solid passage rate. Scaling relationships of rumen digesta load with body weight and the influence on ruminant digesta load in response to climatic region and ruminant feeding type were evaluated. A dataset on rumen digesta load (RDL) parameters bearing body weights of ruminants, proximate chemical composition of feeds and diets fed to or eaten by ruminants and climate type was created. Data were analysed using a linear regression and mixed model regression methodology. Grazers and intermediate feeders had hypoallometric scales of RDL with BW, while the scale was hyperallometric for browsers. Wet and liquid RDL of grazers and browsers scaled isometrically with BW. Intercepts of scaling relationships of RDL and BW were highest for intermediate feeders and lowest for browsers. For all RDL, body mass and animal production were both influential covariates. Ruminant species and ruminant feeding type (p<0.05) influenced all measures of RDL and was highest in grazers and lowest in browsers. The response of RDL to increases in ambient temperature where more linear than they were quadratic. Liquid and dry rumen digesta load were predicted to decrease in proportion by 0.02 (p<0.0001) for every 1°C increase in ambient temperature. Models to estimate the weight of rumen digesta in ruminants were developed. A dataset was created from studies that (1) measured either the rumen dry matter load (RDML), rumen wet matter load (RWML) or rumen liquid matter load (RLML) by complete evacuation of the rumen through fistulas or after slaughtering, (2) reported body weights of animals and (3) stated the diets fed to or eaten by the animals. Factors affecting rumen digesta load were identified from each study and included animal (ruminant feeding type, body weight, degree of maturity, animal production level, days in lactation and pregnancy), diet composition (dry matter, neutral detergent fibre, crude protein, starch and ash content), management (grazing or fed-indoors) and environmental (climate type and ambient temperature) factors. These factors were used as input variables in predicting rumen digesta load. The dataset was divided into 2 subsets: 70% for model training and 30% for testing. The models accounted for 81% (scaled RDML) and 90% (unscaled RDML) of the variation in prediction of RDML. On testing, the models attained 59% (scaled RDML) and 84% (unscaled RDML) precision in prediction. Models attained high precision in prediction of RWML (R2 = 0.94) and RLML (R2 = 0.94) during training and testing of RWML (R2 = 0.85) and RLML (R2 = 0.88) using an independent dataset. In conclusion, the models gave good predictions of the weight of rumen digesta load. However, there is a need to correct for the effect of time delay from the point when feeding stops till when rumen digesta load is measured; this is quite cardinal in regressing in time to the exact rumen digesta load when the animal stopped eating. In summary, results from this study showed that increases in ambient temperature will decrease rumen digestibility of forages and these will be more pronounced in arid regions. Small-sized ruminants adapted their feeding behaviour and rumen digesta load better than large-size ruminants. This implies that local breeds which are generally small in size can be better utilised to mitigate climate change by farmers in arid regions. High accuracy in prediction of feeding behaviour, rumen degradability, passage rate of digesta in the rumen and rumen digesta load would enable better prediction of dry matter intake by ruminants.
Exploring the use of indigenous knowledge to mitigate tick challenges in goats.
(2020) Mkwanazi, Mbusiseni Vusumuzi.; Chimonyo, Michael.
Farmers in developing countries with limited access to orthodox veterinary care commonly use indigenous knowledge. Indigenous knowledge (IK) stems out of peoples' ingenuity, credulity and long insatiable curiosity of the environment and nature that is often passed from one generation to the next. The broad objective of the study was to investigate the use of indigenous knowledge and practices to control ticks in goats. A qualitative study was conducted to explore indigenous practices and methods used to control tick infestation in goats from Jozini Municipality of uMkhanyakude District in South Africa. Data collected included common ticks and associated tick challenges in goats, effects of ticks in goats, new tick species and diseases that have developed. Indigenous methods and practices used to control ticks and associated tick challenges were also captured. Source of knowledge, transference of knowledge to other community members or household members were also requested. Indigenous people have substantial knowledge on ticks exemplified by their ability to differentiate between different tick species. Ticks are traditionally identified using colour patterns and feeding sites. Ticks cause wounds, skin irritation and limping. Nine medicinal plant species were identified to control ticks and their associated challenges and four used to treat tick -borne diseases. A cross-sectional survey was conducted to determine the extent of use of the IK to control tick infestation in goats. Amblyomma tick species were ranked as the most important amongst the tick species, followed by Rhipicephalus evertsi evertsi ticks. A significant population of farmers (81%) depended on the use of tick sprays, whereas others used injections (3%). Cissus quadrangularis L. (Inhlashwana) was the most used ethno-veterinary plant to control ticks with a frequency of (64%), followed by Gomphocarpus physocarpus E. Mey (Uphehlacwathi) (56%). There was no association between the use of IK and cattle, sheep, chicken ownership (P >0.05), although, households that kept cattle less than 30 were using IK more than those with larger herd sizes. The most important purpose of using IK was that it is effective. Farmers older than 55 years were 2.89 times more likely to influence the extent of use of IK compared to farmers less than 30 years who were mostly young farmers. The likelihood of having the presence of herbalist in the particular rangeland was 3.64 times more likely to influence the use of IK (P < 0.05). To determine the relationship between tick count and coat characteristics, BCS, FAMACHA score a total of 96 Nguni goats of different ages based on dentition and sex were used. Weaners had lower tick counts compared to does and bucks. During the hot-dry season, BCS declined faster as tick count increased (p <0.01), compared to the post rainy season. The number of ticks increased (p <0.01) in the hot-wet season linearly as BCS increased whilst, during the cool-dry season, BCS decreased (p <0.01). The rate of change of BCS was higher in weaners as tick count increases compared to does and bucks. There was no relationship between BCS, FAMACHA and PCV on weaners (p >0.05). In the in vitro study aqueous plant extracts were applied at (6, 12 and 18% (v/v) and compared to a commercial acaricide, Eraditick (amitraz) positive control and negative control (distilled water). Extraction solvents used were methanol and acetone. The repellency percentage was highest at 6% v/v for acetone, methanol, and control (distilled water) extracts similar to positive control Amitraz. The acaricidal efficacy of the Gomphocarpus physocarpus at 12% v/v of methanol extracts was as good as that of 6% v/v, however different to that of 18% v/v was relatively low. The mortality rate of the positive control reached 100% after 72 hrs (p < 0.05) post-treatment, though it was similar to that of acetone, methanol, and control across different concentrations. The 6% v/v of Cissus quadrangularis for each extract were more effective (p<0.01) against Rhipicephalus evertsi evertsi ticks. Repellency percentage of Cissus quadrangularis and different extraction solvents declined with time from 30 min to 5 hrs. It was concluded to achieve sustainable veterinary care there is a need to integrate the two knowledge systems into coming up with viable tick control strategies to enhance goat productivity. Also, it is important that when IK policies are implemented, factors that promote its utilisation need to be considered including the participation and interaction of IK custodians. Findings from this study also indicated that tick count increases during hot-wet and hot dry season in goats and cause substantial decline in BCS. It is crucial, therefore, to put measures to counteract the drop in BCS, and increase in tick counts with season, if productivity of the goats is to be improved. Also, ticks can be reduced efficiently in goats using IK, more especially the use of Cissus quadrangularis.Lin and Gomphocarpus physocarpus at a concentration of 6% v/v.
Genetic diversity and differentiation of pelt, mutton and wool sheep breeds of South Africa using genome-wide single nucleotide polymorphisms.
(2021) Dzomba, Edgar Farai.; Chimonyo, Michael.
Sheep, Ovis aries, are a versatile species that has, over hundreds of years, been adapted to South African environmental conditions resulting in more than 40 breeds that are raised for various objectives and production systems and constituting a population of close to 30 million animals. The South African sheep genetic resource presents unique and distinct phenotypes and genotypes that, put together, contribute to the global biodiversity observed in sheep that ought to be conserved and used for improved human livelihoods and economies. South Africa shares its sheep genetics with the global world, through both exportation and importation of germplasm. The broad objective of the study was to profile the genomic architecture of South African sheep populations to provide information for optimal utilization, conservation and improvement. Four hundred South African sheep belonging to 13 breeds of mutton, wool, dual purpose (mutton and wool), pelt and uncharacterised non-descript indigenous sheep were sampled and genotyped. In addition, 623 genotypes from the International Sheep Genomics Consortium representing European, Asian, African sheep breeds were subsampled. A series of statistical genomic analyses were pursued. In Chapter 3, genetic diversity, population genetic structure and divergence between South African sheep breeds was investigated using the OvineSNP50 Beadchip. A total of 400 sheep belonging to 13 breeds representing mutton, pelt and mutton and wool dual-purpose breeds and Nguni sheep as a representative of indigenous non-descript genotypes were genotyped. To gain a clearer understanding of the genetic diversity of South African breeds relative to other breeds, 623 genotypes from six African, two Asian and eight European breeds were included in the analyses. The study demonstrated low genetic diversity (HO ≤ 0.27) in small and geographically restricted populations of Namaqua Afrikaner; Nguni, and Blackhead Persian relative to moderate to high diversity (HO ≥ 0.38) in Merino and Merino-derived commercial breeds (i.e. Dohne Merino, Australian Merino and Chinese Merino). Overall, the African and Asian populations were the most inbred populations with FIS ranging from 0.17 ± 0.05 in Grey Swakara and Ronderib Afrikaner sheep to 0.34 ± 0.07 in the Namaqua Afrikaner. Principal component analysis separated the fat-tailed sheep (i.e. Swakaras, Nguni, Black Head Persian, Ethiopian Menzi, Meatmaster) from the rump-tailed sheep of Merino and Dorset Horn etc., as well as according to breed history and production systems. Similarly, ADMIXTUREbased clustering revealed various sources of within- and amongst-breed genomic variation associated with production purpose, adaptation and history of the breeds. An analysis of FSTv based breed differentiating SNPs suggested selection and population divergence on genomic regions associated with growth, adaptation and reproduction. Overall, the analysis gave insight into the current status of the sheep genetic resources of South Africa relative to the global sheep population highlighting both genetic similarities as well as divergence associated with production system and geographical distribution and local adaptation. The second set of analyses (Chapter 4) focused on assessing the genetic diversity, population structure and breed divergence in 279 animals including the three Merino-derived breeds and five presumed ancestral populations of Merinos and non-Merino founding breeds of Damara, Ronderib Afrikaner and Nguni. Highest genetic diversity values were observed in Dohne Merino with Ho = 0.39 ± 0.01 followed by Meatmaster and South African Merino with Ho = 0.37 ± 0.03. The level of inbreeding ranged from 0.0 ± 0.02 (Dohne Merino) to 0.27 ± 0.05 (Nguni). Analysis of Molecular Variance (AMOVA) showed high within population variance (>80 %) across all population categories. The first Principal Component (PC1) separated the Merino, South African Mutton Merino (SAMM), Dohne Merino and Afrino from the Meatmaster, Damara, Nguni and Ronderib Afrikaner. PC2 aligned each Merino derived breed with its presumed ancestors and separated the SAMM from the Merino and SA Merino. Within population selection based on |iHS| indices yielded selection sweeps across the AFR (12 sweeps), Meatmaster (4 sweeps) and Dohne Merino (29 sweeps). Genes associated with hair/wool traits such as FGF12, metabolic genes of ICA1, NXPH1 and GPR171 and immune response genes of IL22 IL26, IFNAR1 and IL10RB were reported. Other genes included HMGA which was observed as a selection signature in other populations, WNT5A important in the development of the skeleton and mammary glands, ANTXR2 associated with adaptation to variation in climatic conditions and BMP2 which has been reported as strongly selected in both fat-tailed and thin-tailed sheep. Using the Rsb analysis for selection sweeps, the Dohne Merino vs SAMM shared all six sweeps regions on chromosomes 1, 10 and 11 with the comparison for Afrino vs SAMM. Genes such as FGF12 on OAR 1:191,3-194,7Mb and MAP2K4 on OAR11:28,6-31,3Mb were observed. The selection sweep on chromosome 10 region 28,6-30,3 Mb, harbouring the RXFP2 for polledness, was shared between Dohne Merino vs Merino, Meatmaster vs Merino and Meatmaster vs Nguni. The Dohne Merino vs Merino and the Meatmaster vs Merino also shared an Rsb-based selection sweep on chromosome 1 region 268,5 - 269,9 Mb associated with the Calpain gene, CAPN7. The study demonstrated some genetic similarities between the Merino and Merino-derived breeds emanating from common founding populations as well as some divergence driven by breed-specific selection goals. Chapter 5 tested the hypothesis that production systems geared towards specific traits of importance or natural or artificial selection pressures influenced the occurrence and distribution of runs of homozygosity (ROH) in the South African sheep population. The ROH were screened and their distribution within chromosomes and between breeds were analysed to assess breed history and associated selected pressures. ROH were computed at cut-offs of 1-6 Mb, 6-12 Mb, 12-24 Mb, 24-48 Mb and >48 Mb. Analysis of the distribution of ROH according to their size showed that, for all breeds, the majority of the detected ROH were in the short (1- 6 Mb) category (88 %). Most animals had no ROH >48 Mb. Of the South African breeds, the Nguni and the Blackhead Persian displayed high ROH based inbreeding (FROH) of 0.31 ± 0.05 and 0.31 ± 0.04, respectively. Highest incidence of common ROH per SNP across breeds was observed on chromosome 10 with over 250 incidences of common ROHs. Mean proportion of SNPs per breed per ROH islands ranged from 0.02 ± 0.15 (island ROH224 on chromosome 23) to 0.13 ± 0.29 (island ROH175 on chromosome 15). Seventeen of the islands had SNPs observed in single populations (unique ROH islands). The MacArthur Merino population had five unique ROH islands followed by Blackhead Persian and Nguni with three each whilst the South African Mutton Merino, SA Merino, White Vital Swakara, Karakul, Dorset Horn and Chinese Merino each had one unique ROH island. Genes within ROH islands were predominantly associated with metabolic and immune response traits and predomestic selection for traits such as presence or absence of horns. In line with observations in Chapter 3, the frequency and patterns of distribution of ROH observed in this study corresponded to the breed history and implied selection pressures exposed to the sheep populations under study. Chapter 6 investigated (i) LD between adjacent SNPs, (ii) LD decay with increased marker distance, (iii) trends in effective population size over time and (iv) consistency of gametic phase in 13 South African sheep breeds South African Merino (n = 56), Merino (n =10); Mutton Merino (n = 10), Dohne Merino (n = 50), Meatmaster (n = 48), Blackhead Persian (n =14) and Namaqua Afrikaner (n = 12), the four pelt-colour based Swakara subpopulations of Grey (n = 22); Black (n = 16); White-vital (n = 41) and White-subvital (n =17) Dorper (n = 23); Afrino (n = 51) and unimproved Nguni sheep (n = 30). Linkage disequilibrium (r2) averaged 0.16 ± 0.021and ranged from 0.09 ± 0.14 and 0.09 ± 0.13 observed in the SA Merino and Dohne Merino respectively to 0.28 ± 0.29 observed in the Blackhead Persian sheep. Chromosome 10 had the highest LD with r2 values ranging from 0.10 ± 0.15 (SA Merino) and 0.12 ± 0.18 (Dohne Merino) to 0.28 ± 0.30 in Blackhead Persian and 0.29 ± 0.30 (SA Mutton Merino). Across the 14 breeds, LD decayed from 0.27 ± 0.30 at 0-10Kb window to 0.02 ± 0.03 at 1000- 2000 Kb window. A progressive decrease in Ne across generations across all populations was observed with effective population size of <500 for all the populations 66 generations ago decreasing to <250, 23 generations ago and well below 100, 13 generations ago. Highest correlations in gametic phase were observed within the 0-10kb window between pairs of Merino and Merino-derived breeds. The highest correlation observed with Nguni sheep was with Dorper sheep (0.33) within the 0-10kb window, which was similar to that observed with Blackhead Persian sheep and Dorper (0.32) again within the same window. The study reported considerable LD persistent over short distance in the South African sheep breeds. The implications of the observed LD, LD decay and consistency in gamete phase on applications such as GWAS, QTL mapping and GS were discussed. It was concluded that the South African sheep population is highly diverse with that diversity found both within and between populations. Genetic differences between fat tailed sheep population, Merino type breeds and the English Dorset were demonstrated as well as low levels of genetic diversity in small and indigenous breeds such as the Nguni, Namaqua Afrikaner and Blackhead Persian. The frequency and patterns of distribution of ROH observed in this study corresponded to the breed history and implied selection pressures exposed to the sheep populations under study. The utility of the OvineSNP50 Beadchip as a genomic tool for the South African Sheep population was also demonstrated. Keywords: Ovis aries; SNP data; genomic structure; production system; selection signatures; ROH
Behaviour, physiological responses, meat yield and gut morphology of free-range chickens raised in a hot environment.
(2016) Mutibvu, Tonderai.; Chimonyo, Michael.; Halimani, Edward Tinyiko.
It is vital to minimise thermal stress and associated welfare problems for birds reared in hot environments and behaviour is a good indicator of thermal stress. The broad objective of the study was to investigate behavioural, physiological and gut morphological responses of free-range slow-growing chickens raised in a generally hot environement. A total of 488 Naked Neck (NN), Ovambo (OV) and Potchefstroom Koekoek (PK) chickens were used in the study. The experiments conducted in this study explored effect of strain, sex, rearing system and provitamin A bio-fortification of maize on gut development in chickens in the context of thermal stress. Two hundred and eighty-eight NN, OV and PK chickens were separated by sex and reared in either intensive or extensive rearing pens, with twelve birds from each strain per pen. Time budgets on free-ranging and related behavioural activities were determined at 3 different observation periods (0800 h, 1200 h and 1600 h) for 3 weeks. Body weight (BW), random environmental effects; ambient temperature (Ta) and relative humidity (RH) as well as bird stress indicators; rectal temperature (RT), heart rate (HR), breathing rate (BR), tonic immobility (TI), spleen and liver weights were determined for the free-ranging and confined flocks. On the last day of the trial, blood samples were collected from randomly selected birds via brachial venepuncture. Body weight (BW), carcass weight (CW), dressed weight (DW), portion and giblet yields were determined. Gut organs were recovered and weighed on a digital scale within 10 min of slaughter. Intestinal length, weight, ileal villus parameters; villus height (VH), villus density (VD), villus width (VW) and muscularis externa (ME) thickness and apparent villus surface area (aVSA) were assessed. Ambient temperature (Ta) and RH were used to compute a temperature humidity index (THI) and data were subjected to ANOVA with strain, sex and rearing system as the main effects. Time of day influenced (P < 0.01) free-ranging-related behaviours namely; foraging, drinking and preening. Females spent more time compared to males on the same activity and also appeared, generally, more stressed than males. Physiological responses of PK, OV and NN were generally comparable under similar rearing conditions and none of the factors studied had an effect (P > 0.05) on RT. Sex influenced (P < 0.05) VH, aVSA, VW and gizzard weight. Villi were taller, wider, hence greater aVSA in males than females on WM and PABM while ME thickness decreased (P < 0.01) between 18 and 21 weeks of age. Strain influenced (P < 0.05) VW, aVSA, ME thickness, intestine length, liver, gizzard, pancreas and heart weights. Sex of bird influenced (P < 0.05) carcass weight (CW), heart, proventriculus and abdominal fat pad (AFP) weight. The heart, liver and pancreas weights were significantly higher in OV than PK and NN chickens. Strain influenced (P < 0.05) BW, H/L ratio, spleen, relative liver weights, thigh, neck, pancreas, gizzard and crop weights but not TI (P > 0.05). Sex of bird affected (P < 0.05) BW, spleen, relative liver weights, H/L ratio, shank, drumstick and abdominal fat pad (AFP) and pancreas weight. Strain × sex interactions were observed (P < 0.05) on spleen and liver weights. There was negative correlation between time spent foraging and THI. Higher BW and heavier portions were obtained with OV than with NN and PK chickens. Generally, males yielded heavier portions than females of the same strain. Free-range birds experienced crop and gizzard hypertrophy and pancreas atrophy. Free-range males yield heavier cuts and females were fattier than males. It was concluded that rearing system, strain and sex of bird influence gut morphology, physiological responses, meat and fat yield in free-range slow-growing chickens. While free-ranging could minimise stress in birds, mechanisms should be devised to prevent predation in outdoor rearing of birds. Endo- and ecto-parasite infestation, behavioural studies using more elaborate techniques and evaluation of fatty acid profiles are possible areas of future research to help understand, hence improve bird welfare for slow-growing chickens in outdoor systems.
Selenium × zinc interaction on growth performance, carcass traits and semen quality of Large White × Landrace and Kolbroek boars.
(2018) Netshirovha, Thivhilaheli Richard.; Chimonyo, Michael.; Kanengoni, Arnold Tapera.
Abstract available in PDF.
Plant-plant combination: an important option in the phase of failing anthelmintics to control nematodes in small ruminants.
(2018) Fomum, Sylvester Werekeh.; Nsahlai, Ignatius Verla.
The present study was designed to explore how combination phytoanthelmintic therapy can be employed to enhance livestock nematode control in goats and sheep. This was motivated by wide spread emergence of resistant varieties of nematodes and related helminths of livestock against chemical anthelmintics. Ongoing trend of selection for resistance by livestock nematodes has led to general anthelmintic failure, urging exploration and potential implementation of combination anthelmintic phytotherapy as an important option. Selected and tested plant species in the current study included Allium cepa, Aloe van balenii, Ananas comosus, Bidens pilosa, Carica papaya, Crinum macowanii, Gunnera perpensa, Nicotiana tabacum, Ricinus communis, Sarcostema viminale, Trema orientalis, Urtica dioica, Vernonia amygdalina, Zanthozylum capense, Zingiber officinale and Zizyphus mucronata. From preceding studies, anthelmintic activity of plant species in the current project have been linked to some important macro anthelmintic biochemicals and grouped as such into sub-experiments (SEPs). These included alkaloids and condensed tannins in SEP 1, flavonoids in SEP 2 and, proteases and nitrogen compounds in SEP 3. Alkaloids and condensed tannins containing plant species (SEP 1), included Aloe van balenii, Crinum macowanii, Gunnera perpensa, Nicotiana tabacum, Sarcostema viminale, Vernonia amygdalina, Zingiber officinale and Zizyphus mucronata; flavonoid containing plant species (SEP 2) comprised of Trema orientalis, Urtica dioica and Zanthozylum capense; and proteases and nitrogen compound containing species (SEP 3), consisted of Allium cepa, Ananas comosus, Bidens pilosa, Carica papaya, and Ricinus communis. In vitro studies initially tested oven-dried plant vegetative samples at 10g, 20g, and 40g equivalent crude extract in 70% ethanol, and concentrated to 100ml for efficacy on mixed nematode infected Nguni goats and Merino sheep in chapter 3. It sought to test effects of concentration, plant species, animal species, interaction between concentration and plant species, interaction between concentration and animal species, and interaction among plant species, animal species and concentration on efficacy. In SEP 1, animal species (P= 0.0107) and concentration (P= 0.0005) affected efficacy. Interaction between crude extract concentration and animal species affected efficacy (P= 0.0127). In SEP 2, concentration affected (P< 0.0001) efficacy. Animal species affected efficacy (P= 0.0046). Similarly, plant species affected efficacy (P= 0.0572). There were interactions between concentration and animal species (P= 0.0010), concentration and plant species (P= 0.0123) and among concentration, animal and plant species (p= 0.0435). In sub-study (3), animal species affected (P= 0.0004) anthelmintic efficacy. Similarly, concentration affected (P= 0.0002) anthelmintic efficacy. Additionally, interaction between animal species and concentration also affected (P= 0.0015) anthelmintic efficacy. Aloe van balenii was confirmed to exert anthelmintic activity. The following in vitro study in chapter 4 evaluated combined efficacy of plant species possessing similar macromolecule(s), in SEP 1, 2 and 3 on mixed nematode parasites of sheep. It was aimed at evaluating anthelmintic potency of plant species combination with similar macromolecules, and how these molecules relate with anthelmintic trait. Sub-experiment one had twenty one (21) combinations; SEP two, three (3) and SEP three, ten (10). Crude extract of each plant species was obtained by extracting 4 g dry matter (DM) in 70 % ethanol, and each experiment ran thrice. Expected combined efficacy computed as (a + b)/2, and simple synergy (differences between combined and expected efficacies) were also computed. Webb’s synergy was computed using Webb’s fractional product method. Alkaloids, condensed tannins and flavonoids contents were quantified and, simple and multiple regression analyses ran to determine their contribution to anthelmintic efficacy. High efficacies were observed for combined plant species of SEP 1, SEP 2, and SEP 3 but within sub-experiments were not different (P>0.05). Simple synergies were mostly positive, with means of 2.5 ± 0.67 % (SEP 1), 1.8 ± 1.19 % (SEP 2), and 2.8 ± 0.30 % (SEP 3). However, Webb’s synergy were largely negative for SEP 1, SEP 2, and SEP 3, each being lower than zero. Among plant combinations, in SEP 1, condensed tannin and flavonoid contents were different (P< 0.0001), while alkaloid contents was similar (0.3037); in SEP 2 condensed tannin (P< 0.009) and flavonoid (P= 0.0211) contents were different but alkaloid contents were similar (P= 0.07); and in SEP 3, condensed tannin contents were not different (P= 0.4312), while the alkaloid (P= 0.0135) and flavonoid contents (P< 0.0001) were different. For all these macro-molecules, there was no discernible association with anthelmintic efficacy. There was potent activity arising from combinations as exemplified by high efficacy, which in the absence of any correlation is potentially attributed to activity of all macromolecules and bioactivity of other related phytochemicals. It is suggestive of a more complex and intricate macromolecular and biochemical interaction in combinations. In the following trial in chapter 5, combinations were constituted across groups from the former. This was aimed at evaluating efficacy and synergistic effects, and additionally, contribution of alkaloids, condensed tannins and flavonoids to these parameters in vitro in sheep. Intergroup combinations were thirty two (32) for condensed tannins/alkaloids and proteases/nitrogen compounds SEP 1; 13 combinations for flavonoids and alkaloids/tannin plant species in SEP 2; and 15 combinations for proteases/nitrogen compound and flavonoid containing plant species in SEP 3. Each experiment was run thrice. Extraction of plant species was done similarly to the former in chapter 3, and dosing mode also retained, but component plant species in combined pairs were from different SEPs’. Rectal faecal grabs from sheep collected and pooled to constitute test samples (chapter 4), incubated and cultured similarly. On day 13, dosing with combined plant species crude extract at 2.5 ml with double dose concentration of each constituting pair. While some controls were moistened and others treated with 70 % ethanol to eliminate potential solvent killing effect. Larval isolation was done following Baermann technique, counting using McMaster slide on day fourteenth. Corrected mortalities were evaluated following Abott’s formula and adopted as indices of observed combined efficacies. Synergistic effects were computed following Webb’s method and alternatively simple synergy from differences between observed and expected efficacies (a + b)/2. Data was analyzed following general linear model of SAS (2000). Combined efficacies of SEP 1 related species were not different, but high, mean (95.5 ± 0.12 %). Synergistic activities were similar (P= 0.3217), with mean (-4.0 ± 0.12 %). No association occurred between any of alkaloids, condensed tannins or flavonoids with observed efficacy for SEP 1, 2 and 3. Multiple regression analysis to seek any relationship among quantified macromolecules with efficacy was not useful either for SEP 1, 2 and 3. Efficacy of combinations SEP 2 were not different (p= 0.4318). Synergistic means were not different (P= 0.2685), but negative (-5.4 ± 0.34 %). Observed efficacy of combinations in SEP 3 were similar (P= 0.5968) and high, mean (95.8 ± 0.04 %). Webb’s synergy was not different (P= 0.6264) and had mean (-3.8 ± 0.04 %). All synergistic means were negative. Crude extracts of all combinations exhibited anthelmintic activity, but could not be attributed to any specific macromolecule(s). Evidently, there is more to the active principles involved than has been examined in the current study, warranting a more detailed study in succeeding chapter 6. All selected plant species were analyzed for phytochemical composition using GC/MS, in search of anthelmintic and other related biochemicals. Four grams (4 g) dry matter (DM) of each species vegetative material was extracted in 70 % ethanol, 2 μl injected into a chromatoprobe trap, and analysed for biochemical composition. Compound identification carried out using the NIST05 mass spectral library and comparisons with retention times of chemical standards done. Where available, comparisons between calculated Kovats retention indices and those published in the literature were done. Clean chromatoprobe traps run in GC/MS as controls to identify background contamination. Compounds present at higher or similar percentages in controls were contaminants and excluded from analysis. For quantification, each peak area in each sample was quantified and converted to percentage of emission, and emitted mass in Nano grams. Phytochemicals identified belonged to aldehydes, amines, sulphur compounds, nitrogen compounds, Ketones, aliphatic acids, benzenoids, alcohols, lactones, amides, alkaloids, furans and esters. Means were determine, standard deviation, sum, minimum and maximum biochemical content in Nano grams. Reference to previous screening and related bodies of work identified and profiled phytochemicals with anthelmintic and other related biological activities. Fourty six phytochemicals had antibacterial activity, 42 antioxidant activity, 38 antifungal activity, 24 antiviral activity, and 13 anthelmintic activity. Allotment of thirteen anthelmintic related phytochemicals according to occurrence in selected plant species indicated that 2 plants had one, 6 plants had two, four plants had three phytochemicals, and 4 plants four phytochemicals. It is most plausible that anthelmintic and other related biological activities exerted by these plant species are closely linked to some phytochemical(s). The following study in chapter 7 retained and analysed identified phytochemicals in chapter 6 for their relationship with observed anthelmintic efficacy, simple and Webb’s synergies. Pearson correlation coefficient was run to explore association of phytochemical candidates with observed efficacy, simple and Webb’s synergy. Multiple regressions (using a selection option stepwise) were run to explore the influence of various phytochemicals on efficacy, simple synergy and Webb’s synergy, by conducting 10 searches to identify any of such influence. Some phytochemicals had positive influences including (benzofuran, 2,3-dihydro; pyridine, 3-(1-methyl-2-pyrrolidinyl)-, (S)-; 2 propenamide; phytol; 5-hydroxymethylfurfural; furfural) and others negative influences. Some phytochemicals selected to exerted positive influence, did so on both observed efficacy and simple synergy. Both correlation matrix and multiple regression relationships pointed to more consortia of phytochemical action. In chapter 8, this study was designed to evaluate and identify the most effective combined dose of Allium cepa and Vernonia amygdalina (COMBP1); and Ananas comosus and Carica papaya (COMBP2) at 50:50 weight for weight relative to positive control, “Zolvix” on natural nematode infected sheep in vivo. Sheep were fed 1.2 kg each of 4 % urea treated veld hay, crushed yellow maize and milled Lucerne hay in ratio 1:1:1. Treatment doses included 5 g, 10 g, 15 g, and 20 g dry matter equivalent extract in 100 ml of 70 % ethanol. Two experiments; the first, evaluated egg per gram (epg) change post treatment and the second, egg hatch and larval recovery. Fifty six Merino ewes averaging 45.0 ± 0.09 kg were weighed and initial epg count done. Both parameters used as covariates at allotting sheep to treatment doses and control of experiment one. Effects of treatment over time, and interaction between treatment and time on epg were evaluated weekly for 4 weeks. In the second trial, faecal grabs from each treatment in the former were pooled, mixed and three sub-samples of 4 g incubated and cultured for egg hatch and larval recovery post treatment on days 1, 14 and 28, relative to negative control from untreated sheep. Effects of treatment, time and, interaction between treatment and time evaluated relative to egg hatch and larval recovery. In trial one, for COMBP1, initial sheep weight were similar, whereas final weight were higher (P< 0.05). Differences between initial and final weight were similar. Epg preceding dosing and others post treatment at end of weeks’ 1, 2 and 3 were lower. Epg at end of week’s 4 were higher (P< 0.05). For COMBP2, initial sheep weight preceding treatment were similar, whereas weight post treatment were mostly similar, but partially higher for treatments 1, (5 g DM equivalent crude extract), (P< 0.05). Initial epg pre-treatment for COMBP2 were similar (P> 0.05). Mean epgs post treatment at end of weeks’ 1, 2 and 3 were lower, while that of week’s 4 were higher (P< 0.05). In trial two, egg hatch and larval recovery for COMBP1 were lower for all treatments on day 1 and 14, but oppositely higher for day 28 (P< 0.05). Mean egg hatch and larval recovery of COMBP2 for days 1 and 14 were lower, whereas that of 28 day post treatment were higher (P< 0.05). Egg hatch and larval recovery increased with time (P< 0.0219). Similarly, interaction of treatments and time resulted to higher egg hatch and larval recovery (P= 0.0496). Treatment trends for both combinations were seemingly consistent for the first two weeks post treatment. During experiment one of this project, there were differences in plant species, animal species (goats and sheep), concentration of plant species crude extract and their interactions in relation to efficacy. In vitro combination phytotherapy, pairs of plant species carrying similar and different anthelmintic macromolecules exerted potent efficacy with little or no antagonism, whereas the same macromolecules did not associate with efficacy. Interaction of biochemicals in both combinations of plant species containing similar macromolecules, and combinations involving different macromolecules would most likely have been different though. Identification of various biochemicals from GC/MS analysis linked anthelmintic and other related activities to some biochemical candidates, some of which were not macromolecules tipped initially to exert this activity. This was suggestive of a wide range of biochemical interactions among these phytochemicals leading to observed combined anthelmintic activity. Multiple regression analysis also failed to linked macromolecules to anthelmintic efficacy. In relation to efficacy vis a vis identified biochemicals, some related positively, while others related negatively, and such interactions have been associated with exercise of medicinal traits by plants. It was observed in vivo studies in sheep, that combination anthelmintic therapy of Allium cepa and Vernonia amygdalina (COMBP1); and Ananas comosus and Carica papaya (COMBP2) exerted anthelmintic activity, but most likely required a second dose following fast waning activity of the first. This will potentially sustain activity longer and improve control. It is recommended that this be done, as it is critical to advancing research in this area.
Influence of physical state of farm housing and processing facilities on quality and safety of dairy milk products.
(2018) Paraffin, Annah Shingirai.; Chimonyo, Michael.; Zindove, Titus Jairus.
The broad objective of the study was to determine the influence of physical state of farm housing and milk processing facilities on the quality and safety of milk and its products. Data collected from urban areas (n =135) and non-urban areas (n =135) households were used to investigate consumer perceptions of milk safety and consumption preferences of dairy products. Data collected from large-scale dairy farmers (n=158) and small-scale dairy farmers (n=186) were used to investigate the perception of milk producers on milk quality and safety. Milk records collected from large-scale dairy farms (n =78) and small-scale farms (n =126) were used to determine the effect of physical state of farm housing and milking practices on total bacteria counts (TBC), somatic cell counts (SCC), protein, butterfat (BF), solids non-fat (SNF), lactose and total solids (TS). Milk records collected from large-scale (n =12) and small-scale (n = 15) dairy processors were used to estimate the influence of physical state of milk processing facilities on presence of E. coli and coliforms in buttermilk. Urban households were 2.8 times more likely to consume fresh milk compared to their non-urban counterparts (P < 0.05). Households from urban areas were twice more likely to purchase fresh milk from kiosks, while households from non-urban areas were five times more likely to buy fresh milk from vendors. The likelihood of appearance, quality and nutritional value being important to households during selection of milk products was higher in urban locations compared to non-urban locations (odds ratio estimates of 4.29, 4.49 and 6.75, respectively). Knowledge and awareness of milk safety issues was more important to urban households. Large-scale farmers were three times more likely to consider breed affecting milk quality compared to their small- scale counterparts. Post milking contamination of milk was perceived to occur during transportation by small-scale farmers, whilst large-scale farmers ranked storage as an important source of contamination post-milking. The likelihood of milk safety being important was twice higher in large farms compared to small-scale farms (P < 0.05. The majority (70%) of large-scale farms had milking parlour doors, windows and fly proofing in poor physical state. More than fifty percent of small-scale farms had milking parlour doors, windows and fly proofing in good physical state (P < 0.01). Most of the large-scale farms used pumps to deliver their milk to storage tanks whilst most of the small-scale farmers used the pouring method (P < 0.05). The TBC and SCC in milk from dairy farms where the wash rooms that had doors, floors, walls and ventilation were in a good physical state were higher than from those farms where the wash rooms were in poor physical state (P < 0.05). Farms that used machine milking and automatic milking cleanings system had lower TBC and SCC in milk compared to farms that used manual milking or hand washing (P < 0.05). The butterfat and protein content in milk from dairy farms with milking facilities that had poor physical state of ceilings, ventilation and floors was lower than those in good physical state (P < 0.05). The butterfat, protein, lactose and solids non-fat (SNF) content in milk from farms that utilised hand milking was higher than dairy farms that used milking machines (P < 0.05). The likelihood of buttermilk from processors with buildings, processing and packaging areas that had poor physical state of drains, roofs, fly-proofing, windows having E. coli and coliforms was 1.2 times higher than those facilities in good physical state. Processors without quality assurances systems or food safety training were twice more likely to produce buttermilk contaminated by E. coli and coliforms (P < 0.05). Poor physical state of ceilings, doors and floors and poor drainage systems at farms results in production of milk with high bacterial count and presence of E. coli and coliforms in buttermilk.
Response in growth performance, blood metabolites, nutrient digestibility, digesta characteristics and carcass characteristics of Windsnyer pigs fed increasing levels of potato hash silage.
(2017) Ncobela, Cyprial Ndumiso.; Chimonyo, Michael.; Kanengoni, Arnold Tapera.
Abstract available in PDF file.
Antioxidant activity of Vachellia species, pork quality and fatty acid composition from pigs supplemented with graded levels of Vachellia tortilis leaf meal.
(2017) Khanyile, Mbongeni.; Mapiye, C.; Chimonyo, Michael.
Abstract available in PDF file.
Physicochemical properties of fermented liquid potato hash diet treated with or without exogenous enzymes and their effects on feed intake, growth performance and carcass characteristics of growing large white x landrace crossbred pigs.
(2017) Thomas, Ronald Sylvester.; Chimonyo, Michael.; Kanengoni, Arnold Tapera.
Abstract available in PDF File.
Optimal energy to total Lys ratios for broiler performance from day old to 35 days of age.
(2017) Crots, Franscois.; Ciacciariello, Mariana.
Abstract available in PDF file.
Influence of age and sex on carcass and meat quality traits of scavenging guinea fowls.
(2016) Musundire, Mabel Tafadzwa.; Chimonyo, Michael.
The purpose of the study was to determine the effect of age and sex on carcass and meat quality characteristics of scavenging guinea fowls in communal production systems. A total of 151 smallholder farmers in Wedza district of Zimbabwe participated in a survey to identify management practices and possible opportunities and constraints in guinea fowl production. Guinea fowls are a tool of alleviating poverty as a potential source of food and income for women who dominated ownership (53.4 %). The majority of the household heads were aged below 55 years. Crops were the main source of income to 46.8 % households whilst 9.8 % households depended on livestock as a source of income. The average guinea fowl flock size per household was 11.36 (SD = 15.44). Guinea fowls were kept mainly for households consumption (ri = 0.44) and income generation (ri = 0.35). Eggs were considered as the main food source followed by meat. About 66.4 % of households did not practice breeding, with the traits selected for included body frame (ri = 0.39), body weight (ri = 0.12) and mothering ability (r = 0.11). The majority of farmers (97.3 %) supplemented feed using locally available feed resources and provided water for their flocks. Keets struggled most from water shortages (ri = 0.45). Predation by birds of prey (ri = 0.31), diseases (ri = 0.22) and wild animal attacks (ri = 0.19) were the main causes of mortality. Ethnoveterinary medicines such as Aloe species and Capsicum frutescens were mostly used to treat diseases. The main constraints which reduced production were lack of capital and feed, and predation. Carcass characteristics, internal organ weights and physicochemical properties of breast meat from 48 scavenging guinea fowls were determined. Guinea fowls comprised of 25 females and 23 males made up of 21 growers (4 – 8 months old) and 27 adults (one year old). In addition, the carcass characteristics, internal organ weights and physicochemical properties of 48 scavenging chickens were used as a benchmark with no statistical comparison with guinea fowls. Chickens comprised of 18 females and 30 males with 19 growers (4 – 8 months old) and 29 adults (one year old). Adult guinea fowls had higher (P< 0.05) cold dressed weight than growers (673.1 ± 11.40 and 630.5 ± 12.34 g/kg BW, respectively). Dressing percentage was higher (P < 0.05) in adult (69.3 ± 0.92 %) than grower (64.7 ± 1.00 g) birds. There was no influence (P > 0.05) of sex on carcass weight. Growing guinea fowls had significantly heavier (P < 0.05) relative weights of leg, thigh and drumstick as compared to adults. Breast weight in males was heavier (P < 0.05) than in females (198.7 ± 5.37 g and 178.8 ± 6.25 g, respectively). Relative abdominal fat weight was higher (P < 0.05) in adults than in growers (24.5 ± 0.57 versus 20.7 ± 0.62 g/kg BW, respectively). Females had significantly higher abdominal fat weight than males. The back weight in adults of 148.7 ± 6.02 g was higher (P < 0.05) than 120.6 ± 6.52 g in growers. Sex had no significant effect (P < 0.05) on carcass remainders. Growers had heavier (P < 0.05) kidney, heart, lung and gizzard weights than adults. Total intestine length in growers (113.2 ± 4.15 cm/kg BW) was longer (P < 0.05) than in adults (74.3 ± 3.90 cm/kg BW). Similarly, growing birds had longer (P < 0.05) large intestines than mature birds. No sex differences (P > 0.05) were observed for intestinal lengths. Dry matter content decreased (P < 0.05) with age from 28.7 ± 0.81 % in growing birds to 24.7 ± 0.75 % in adult birds. Ether extract and ash were higher (P < 0.05) in adult than grower birds. Females had more (P < 0.05) fat content than males. Age and sex had no effect (P > 0.05) on crude protein. Meat from adult birds was darker, redder and yellower (P < 0.05) than from growing birds. Breast muscles from females (b* = 9.0 ± 0.32) were yellower (P < 0.05) than from males (b* = 7.9 ± 0.28). Shear force was higher (P < 0.05) in adults than growers. Cooking loss of 21.2 ± 0.42 % in growers was higher (P < 0.05) than 16.4 ± 0.39 % in adults. It was concluded that meat yield, carcass traits and meat quality vary with age and sex of guinea fowls.
Effect of roughage processing and feeding level on production, reproduction, and growth performance of the Red Maradi goat.
(2016) Abdou, Nourou.; Nsahlai, Ignatius Verla.; Gouro, Abdoulaye S.
Abstract available in PDF file.
Influence of water stress on feed intake, growth performance and nutritional status of Nguni goats.
(2016) Mpendulo, Conference Thando.; Chimonyo, Michael.
The broad objective of the study was to determine the influence of water stress (water deprivation, water restriction and water salinity) on feed intake, growth performance and the nutritional status of Nguni does. A cross-sectional survey was conducted to 135 farmers that keep goats from Jozini municipality of uMkhanyakude district in South Africa. Data collected included household demographics, goat production constraints, watering and feeding systems practised, including data regarding whether farmers milk goats. Varying periods of water deprivation (0, 24 and 48 h) on water intake, feed intake, water to feed ratio, average daily gain and feed conversion ratio were determined. Varying levels of water restriction (1000, 1200, 1400, 1600, 1800 and 2000 mL) and water salinity (0, 5.5 and 11 g/L) on average daily feed intake (ADFI), water to feed ratio (WFR), average daily gain (ADG) and feed conversion ratio (FCR) of Nguni goats were determined. Varying periods of water deprivation (0, 24 and 48 h) on body condition scoring (BCS), body weight (BW), faecal egg counts (FEC), FAMACHA scores, glucose, creatine, urea and cholesterol of Nguni goats were also determined. Varying levels of water restriction (1000, 1200, 1400, 1600, 1800 and 2000 mL) and water salinity (0, 5.5 and 11 g/L) on body condition scoring, body weight, faecal egg counts, FAMACHA, glucose, creatine, urea and cholesterol of Nguni goats were determined. Farmers were not aware of the value of goat milk, and they largely value meat from goats (P <0.01). Female farmers were likely to face water challenges (P <0.05). Farmers practising the scavenging production systems were likely to experience feed challenges. The ADWI was the same in goats deprived of water for 0 h and 24 h (P <0.05). The ADFI was largest for goats deprived of water for 48 h (P <0.01). The ADG and FCR declined as the level of water deprivation was increased (P <0.01). Water deprivation period was negatively correlated with ADFI, WFR, ADG and FCR. The ADFI peaked at 1600 mL of water restriction for goats subjected to 0 and 5.5 g/L of water salinity (P <0.01). The ADG peaked at 1400 and 1600 mL of water restriction across all water salinity levels (P <0.05). Body condition scoring and body weight were largest for goats deprived of water for 0 h (P <0.01). The FEC increased as water deprivation period was increased. Correlations between water deprivation period with FAMACHA, BCS and BW were negative. Correlations with FEC and creatine kinase were, however, positive. The BCS and FAMACHA scores to the peak, and later declined beyond 80 % of water restriction for goats subjected to 0 and 5.5 g/L of water salinity (P <0.05). The BW increased as the level of water restriction decreased across all water salinity levels tested (P <0.01). The FEC decreased as the level of water restriction decreased for goats subjected to 0 and 5.5 level of water salinity (P <0.05). Creatine concentration decreased as the level of water restriction was decreased across all water salinity levels tested (P <0.05). There was a linear relationship between urea and water restriction for goats subjected to 0 g/L of water salinity (P <0.05). It was concluded that goats are constrained by lack of input resources such as water. On the other hand, water deprivation period can be set to 24 hours for Nguni goats since increased periods of water deprivation compromise goat productivity. Also, water restriction and water salinity for Nguni goats can be set to 1600 mL and 5.5 g/L, respectively since further increments do not seem to improve goat productivity. Key words: water resources, water stress, productivity, Nguni goats.
Ecological benefits of brachiaria grasses in integrated crop-livestock production systems in Rwanda.
(2016) Mupenzi, Mutimura.; Nsahlai, Ignatius Verla.
A study was conducted with the broad objective to evaluate ecological benefits of Brachiaria grasses in integrated crop-stall-fed livestock production systems in humid and semi-arid region of Rwanda. The specific objectives of the study were: (1) To identify factors that determine household feed resource supply and willingness to plant improved fodder in humid and semi-arid regions of Rwanda; (2) To determine nutritive values of available feed resources used by smallholder farmers in Rwanda; (3) To determine biomass and nutrient productivity as well as cutting management of promising Brachiaria genotypes for semi-arid ecologies in Rwanda (4) To determine nutritional value of Brachiaria species, on stall-fed replacement dairy heifers with or without concentrate supplements; (5) To examine the biophysical and physiological basis that make Brachiaria grass a more palatable and nutritious forage with impact on lactation in dairy cows relative to Napier grass. A structured questionnaire was administered to 204 households of semi-arid and humid environments and used to determine major livelihood options and characterise integrated crop-livestock production systems. Farming was the major livelihood strategy among households in semi-arid and humid areas. The diversity of livestock species including, dairy cattle among households were more in semi-arid than in humid environments. Milk yield was higher in Jersey than in other dairy cows under smallholder farm prevailing conditions. Logistic regression analysis showed that age, level of education and experience in livestock rearing of household head significantly influenced adoption of planted forages in smallholder farms in both areas. Farmers in semi-arid area were twice more likely to establish improved fodder species in farmland than those from humid areas. Napier grass and a variety of crop residues were the major feed resources in both the rainy and dry seasons in both areas. Feed resource inventorying depicted a wide (n=24) species diversity from both on-farm and off-farm source five of which were unique to semi-arid areas. Chemical composition, ii contents of metabolisable energy (ME), organic matter digestibility (OMD) and neutral detergent fibre digestibility (NDFd) and rumen fermentation characteristics partitioning factor (PF) were highly variable, depicting variability in their efficiencies of utilisation in microbial functions and post-ruminal nutrient supply for maintenance and production. Brachiaria genotype and cutting management study involved an evaluation of five cultivars (cv.) of Brachiaria brizantha, one cultivar of B. humidicola, two cultivars of Brachiaria hybrid and one cultivar of Brachiaria decumbens against Napier grass (Pennisetum purpureum) in an on-farm trial in a completely randomised block design (RCBD) with four replicates. Forage samples were collected at 60, 90 and 120 days after planting (DAP). Samples of each cultivar and age of cutting were analysed for concentration of dry matter (DM), crude protein (CP), organic matter (OM), neutral detergent fibre (NDF), minerals, in vitro apparent degradable dry matter (ivADDM), metabolisable energy (ME) and in vitro gas production (GP) kinetics. The DM, CP, OM, ivADDM and digestible OM increased from 60 to 90 DAP and declined thereafter. The NDF contents increased while CP contents decreased consistently with increase in age. Macro and micro-nutrient concentrations were also higher at 90 DAP. The ME differed (P<0.05) among grasses and between DAP. The GP of grasses cut at 90 DAP was higher than the other two DAP. The highest yield cultivars were Basilisk, Marandú and Piatá. The optimum age of cutting was species specific, but overall cutting at 90 DAP was recommended. In a study on changes in growth performance of crossbred dairy heifers under cut-and-carry feeding system, sixteen crossbred (Ankole × Jersey) heifers (Average body weight 203±35 kg) were randomly allocated to two dietary treatments. Brachiaria hybrid cultivar Mulato II with 2 kg/day of commercial concentrates (MCC) and Napier grass (Pennisetum purpureum) with the same supplement (NCC) were fed to heifers for 12 weeks. Feeds, mineral lick and water were provided ad libitum. Absolute daily dry matter intake (g DM/day) and relative intake (g/kg of metabolic body weight - BW0.75) were higher in heifers fed on MCC than in heifers fed on NCC (P<0.001). Feed conversion ratio was lower (P<0.001) in MCC than NCC diets. Final body weight (FBW) and body weight gain (BWG) did not differ between the two groups of heifers (P>0.05). Average daily weight gain (ADWG), also not differed significantly (P>0.05). To determine biophysical factors affecting quality of Brachiaria sp. and impact on performance in crossbred dairy cattle, a feeding trial was conducted using 40 lactating crossbred (Ankole × Holstein Friesian) in second parity and in 10–15 days in milk in collaboration with 40 farm households. Experimental diets were Brachiaria brizantha (cv. Piatá) and Napier grass (Pennisetum purpureum–used as control) as sole or mixed forage with Desmodium distortum (70:30 w/w fresh basis). Chemical analysis showed that Napier was low in DM, OM, and CP, but higher in NDF and ADF than the test Brachiaria (P<0.001). The composition varied with duration of the experiments (P<0.05) but not across farms (P>0.05). Voluntary intake did not differ across diets (P>0.05) but was consistently higher in Piatá-based than in the Napier-based diets. Average milk production with higher in cows fed on the test Brachiaria-based than in the Napier-based diets (P<0.001). Cows fed grass-legume mixes recorded higher milk than sole grass diets. Digesta flows and degradation rates were also rapid in grass-forage than in sole grass diets (P<0.001). The most promising cultivars identified from this study were cv. Basilisk, cv. Marandú and cv. Piatá, because of its nutritional characteristics as well as nutrient yields which were higher and more comparable with Napier grass than other grass cultivars. The feeding trial with replacement dairy heifer proved that depriving these animals the nutritional advantage associated with selectivity in forages did not compromise the nutritional value cv. Mulato II; hence, this cultivar can effectively be used as quality fodder for cut-andcarry dairy system. Digestive physiology of Piatá-based diet provided a strong, but indicative evidence of the differences in palatability, voluntary intake and impact on lactation between cv. Piatá and Napier grass. These differences might have associated with physical effectiveness of NDF.

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