Doctoral Degrees (Animal and Poultry Science)

Permanent URI for this collectionhttps://hdl.handle.net/10413/6570

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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.
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.
Effects of hydric stress on the growth, blood chemistry and meat quality characteristics of indigenous chickens.
(2013) Chikumba, Nation.; Chimonyo, Michael.; Nsahlai, Ignatius Verla.
The broad objective of the study was to determine the effects of restricted water intake on the growth, blood chemistry and meat quality characteristics of indigenous chickens in semi arid environments. A total of 15 flocks in communal villages and 12 flocks in resettlement schemes of Msinga District in South Africa were monitored for 30 months to determine the effects of production system and season on flock size, dynamics and constraints faced by indigenous chicken producers. As a follow up, 281 and 233 chicks hatched in November 2011 from 18 and 9 households in communal villages and resettlement schemes, respectively were monitored using a structured checklist to determine survival and causes of mortality from hatching up to 12 weeks of age. Kaplan-Meier survival distributions and the odds ratios for effects of potential risk factors were determined using survival analysis and logistic regression models, respectively. Flock composition and structure were significantly affected by production system and month. Farmers in resettlement schemes had approximately one cock and three hens more (P < 0.05) than those in communal villages. The number of growers and chicks were similar (P > 0.05) between the two production systems but chicks were the predominant age group (38 %) of each flock. The cock to hen ratio in households in communal villages was 1:3.5, while that in resettlement schemes was 1:3.7, suggesting that inbreeding might have been reducing flock productivity. Flock sizes in communal villages peaked in March (45.1 ± 3.02) during the post rainy season and declined steadily to a low of 34.7 ± 3.63 in September during the hot-dry season. The largest flock sizes in resettlement schemes were observed in January (52.4 ± 5.09) during the hot-wet season and the smallest in August (36.1 ± 5.98) during the cold- dry season. Households in communal villages had more chicks (P < 0.05) than cocks, hens and growers throughout the year except in June when the number of growers was equal to that of chicks. In resettlement schemes, the number of chicks was lower (P < 0.05) than the number of hens and growers, except in June and July when it was equal to that of growers. Total entries were not affected (P > 0.05) by production system. Hatched chicks were the major mode of entry, accounting for more than 97 % of entries into flocks. The contribution of purchases, gifts and exchanges was negligible. Mortality was the main cause of exits from flocks, accounting for 70 and 63 % of total exits among households in communal villages and resettlement schemes, respectively. The major causes of mortality were aerial predators, sub-optimalnutrition and inclement weather conditions, which were similar between production systems. The number of birds that exited flocks through slaughter for household consumption was higher (P < 0.05) among households in resettlement (34% of total exits) than communal villages (21 % of total exits). The proportion of chickens exiting flocks through sales was higher in communal (9 %) than resettlement (4.3 %) households. Chick survival from hatching to 12 weeks was higher (P < 0.05) in communal villages (55 ± 3.14 %) than in resettlement schemes (41 ± 4.19 %). Mean chick survival time did not differ (P > 0.05) between communal (56 ± 3.30 days) and resettlement (49 ± 3.23 days) flocks. Provision of water ad libitum and treatment of sick birds were important covariates in prolonging the survival time of chicks. The effects of restricted water intake on growth performance, blood chemistry, physicochemical properties, and sensory characteristics of meat from Naked Neck (NNK) and Ovambo (OVB) chickens were also assessed. In the experiment, 54 pullets of each strain with an average weight of 641± 10g per bird were randomly assigned to three water restriction levels for 60 days in a completely randomized design. The treatments were ad libitum, 70% of ad libitum and 40% of ad libitum water intake. Each treatment group was replicated three times. The pectoralis (breast) muscle was sampled for meat quality, fatty acid composition and sensory quality analyses. Ovambo chickens had superior body-weight at 16 weeks of age, average daily gains (ADG) and average daily water intake (ADWI) than NNK chickens. Body weight of birds at 16 weeks of age, ADG, average daily feed intake (ADFI), ADWI and water to feed ratio (WFR) declined progressively (P < 0.05) with increasing severity of water restriction, while food conversion ratio (FCR) values increased (P < 0.05) as the severity of water restriction increased. Naked Neck chickens had better FCR at the 40 % of ad libitum water intake level than OVB chickens. The dressing percentage per bird was higher (P<0.05) in water-restricted birds than those on ad libitum water consumption, irrespective of strain. Heart weight was significantly lower in birds on 40% of ad libitum water intake than those on ad libitum and 70% of ad libitum water intake, respectively. Packed cell volume was higher (P < 0.05) in NNK than OVB chickens offered waterad libitum, but similar in birds offered 70 and 40 % of ad libitum. There were no differences in erythrocyte count (RBC) and mean corpuscular volume (MCV) values between strains, but MCV was higher in birds on 40 than 70 % of ad libitum water intake, irrespective of strain. Naked neck chickens had higher (P < 0.05) white blood cell count (WBC) values than OVB chickens at 40 % restriction level, but lower WBC than OVB at 70 % water restriction level. Uric acid, creatinine, triacylglycerides, total cholesterol, low density lipid cholesterol, total protein and globulin increased (P < 0.05) with each increment in water restriction, but the increase in creatinine and total cholesterol was more pronounced in OVB than NNK chickens. The opposite was observed for uric acid. Alanine transaminase, alkaline phosphatase and aspartate transaminase activities were not influenced by strain and water restriction. It was concluded that the two strains could withstand up to 40 % of ad libitum water restriction, but NNK chickens tolerated water stress better than OVB chickens. Water intake levels of 40% of ad libitum produced meat with significantly lower (P < 0.05) cooking loss, and higher (P < 0.05) redness (a*) values in NNK chickens compared with OVB chickens. Water intake level had no effect (P > 0.05) on lightness (L*) and yellowness (b*) values, shear force, moisture and protein contents in both strains. The fat content of NNK meat was 41 % lower (P < 0.05) than that of OVB meat at 70 % of ad libitum, but 31 % higher at 40 % of ad libitum water intake. The ash content was significantly elevated (P < 0.05) in birds on 70 % of ad libitum compared to those on ad libitum and 40 % of ad libitum water intake, which had similar (P > 0.05) ash contents. Birds on 40 % of ad libitum water intake had significantly higher (P < 0.05) proportions of octadecanoic acid (C18:0), cis, cis-9,12-octadecadienoic acid (C18:2 ῳ-6), cis-8,11,14,17-eicosatetraenoic acid (C20:4 ῳ-6), cis-7,10,13,16-docosatetraenoic acid (C22:4 ῳ-6), cis-4,7,10,13,16,19-docosahexaenoic acid (C22:6 ῳ-3), total polyunsaturated fatty acid (PUFA), total omega-3 PUFA and total omega-6 PUFA proportions, but lower (P < 0.05) cis-7-hexadecenoic (C16:1c7), cis-9-octadecenoic (C18:1c9), cis-11-octadecenoic acid (C18:1c11), cis-13-docosenoic acid (C22:1c13), total monounsaturated fatty acids than those on the 70% of ad libitum and ad libitum water intake, respectively. The proportion of trans-9-octadenoic acid (C18:1t9) was higher (P < 0.05) in NNK chickens on 40 % of ad libitum water intake than OVB chickens. It was concluded that water restriction at 40 % of ad libitum water intake resulted in favourable cooking loss values and meat redness (a*) values, omega-3 and 6 PUFA proportions and a high ῳ-6/ῳ-3 ratio. The high fat content of NNK chickens at 40 % of ad libitum water intake compared to OVB chickens suggests a superior adaptation to hydric stress. Naked Neck breast meat had higher initial impression of juiciness scores than that from OVB chickens, but only in birds on ad libitum and 70 % of ad libitum water intake. Sensory scores for first bite, connective tissue and tenderness decreased with increasing severity of water restriction (P < 0.05). Aroma, flavour and atypical flavour were not affected by strain or water restriction level (P > 0.05). There were significant strain differences for sustained impression of juiciness and tenderness, with the highest scores occurring in NNK chickens (P < 0.05). Aroma had a significant influence on the flavour of breast meat (P < 0.05). Fat content was significantly correlated with initial impression of juiciness, first bite and sustained impression of juiciness of breast meat. It was concluded that water restriction up to 40 % of ad libitum had a significant and adverse impact on juiciness and first bite scores of meat.
Effects of physicochemical properties of fibrous feed on feeding behaviour and gut health of growing and finishing pigs.
(2013) Bakare, Archibold Garikayi.; Chimonyo, Michael.
The broad objective of the study was to determine feeding behaviour and gut health of pigs fed different fibres at varying inclusion levels. Maize cob, maize stover, sunflower hulls, veld grass, sawdust, lucerne and dried citrus pulp were used in growing and finishing pig diets to provide a wide range of physicochemical properties. Time spent eating, drinking, lying down, sitting/standing and other activities was observed using video cameras. Blood samples were collected at the end of the trial for both growing and finishing pigs for analysis of glycated haemoglobin, albumin, globulin, total protein, creatine kinase, urea and uric acid. Intestinal segments were collected at the end of trial for growing pigs to determine mucosal architecture of the intestines. Digestible energy (DE), bulk density (BD), acid detergent fibre (ADF) and water holding capacity (WHC) were the most important variables predicting time spent on different behavioural activities in growing pigs (P < 0.001). Water holding capacity, neutral detergent fibre (NDF) and ADF were the most important variables involved in predicting time spent on different behavioural activities in finishing pigs (P < 0.001). Physicochemical properties influenced time spent on different behavioural activities and they provided relationships with time spent on different behavioural activities in both growing and finishing pigs. Glycated haemoglobin, albumin, globulin, total protein and uric acid were factors that influenced time spent eating in growing pigs (P < 0.05). In finishing pigs, only serum total protein was selected as the best predictor variable influencing time spent eating (P < 0.05). The blood metabolites were correlated with time spent eating and drinking. They provided threshold values with time spent eating and drinking by pig. Hence, they can also be used as potential biomarkers that modulate neuronal pathways which reduce time spent eating and drinking. In this study, bulk density (BD) and NDF were the best predictor variables influencing villi height (VH) and apparent villi surface area (AVSA) in pigs (P < 0.05). Grouped pigs fed fibrous diet spent more time eating, lying down, standing, walking and fighting (P < 0.05). Skin lesions appeared the most on neck and shoulder region followed by chest, stomach and hind leg region, and finally head region (P < 0.05). Fibrous diet did not reduce aggressive behaviours, rather aggressive behaviours emanated out of frustration when queuing at the feeder. It was concluded that physicochemical properties of fibrous diets and nutritionally-related blood metabolites influence feeding behaviour. Mucosal architecture was also influenced by physicochemical properties of the fibrous diets.
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.
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.
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
Improving the nutritive value and utilisation of non-conventional protein feed resources in smallholder village chicken production systems.
(2014) Dos Anjos, Filomena Rosa.; Chimonyo, Michael.; Ledoux, D.
Poultry production is one of the most important activities for creating wealth in developing countries. This study was conducted to assess methods of improving the nutritive value and utilization of cowpeas, and ameliorating the negative effects of aflatoxins in chicken feeds. Farmer perceptions on feed resource availability and utilization of non-conventional feed resources for indigenous chickens were investigated in three Mozambican districts (n=240). Scavenging was the major source of feeds for chickens and two out of five of the respondents experienced feed shortages during the dry season (from May to October/November). Nearly 90 % of the respondents were willing to use novel protein sources (e.g. houseflies, earthworms and snails) as chicken feed. Household leftovers were identified as the major supplemental feed source, followed by kitchen waste, then crushed grain and maize bran, suggesting protein is deficient in chicken diets. Most often, the kitchen scraps include foods that are spoiled with mould or damaged by insects and are not used in human consumption. Farmers had no specific biases against the use of non-conventional feed ingredients for chickens. Households in mountain zones were more likely to use maize bran for feeding chickens than those near dams (odds ratio 8.26). Educated farmers were three times more likely to feed chickens with maize bran (odds ratio 3.01). Topography highly influenced household’s likelihood of experiencing feed shortage. Farmers in mountains zones were 2.3 times more likely to experience feed shortage than the farmers in dam areas. Households headed by females were 1.2 times more likely to experience feed shortage than households headed by men. Chemical composition, amino acid digestibility and the true metabolisable energy of cowpeas and pigeon peas- under various processing (heat and enzyme) treatments, as well as effects on growth performance, growth of internal organs, and gut health were investigated through feeding trials. The precision-fed cecectomized rooster assay was used to determine amino acid digestibility and true metabolizable energy of cowpeas. Crude protein (CP) content was higher (P<0.05) for raw nhemba cowpea (228 g/kg) in comparison to raw black-eyed beans (207 g/kg). Except for tryptophan, amino acid contents were higher (P<0.05) in nhemba than in black-eyed beans. Trypsin inhibitor levels in nhemba averaged 6700 TIU/g, whereas the black-eyed beans contained 2200 TIU/g. Both roasting and extrusion increased the CP content of cowpeas. Extruded and roasted black-eyed beans contained higher (P>0.05) amino acid concentrations compared with raw black-eyed beans. Heat treatment had no effect (P>0.05) on the levels of methionine, threonine, proline, alanine, valine or leucine. The amino acid content of nhemba was reduced (P<0.05) by heat treatment. Heat treatment reduced (P<0.05) the concentration of trypsin inhibitors to below 2000 TIU/g. Roasting had no effect (P>0.05) on amino acid digestibility in black-eyed beans, but increased amino acid digestibility of nhemba by 3.4 %. True metabolizable energy (TMEn) was significantly increased (3535 versus 3164 kcal/kg) by extrusion. Body weight gains, feed conversion and gut morphology demonstrated that, despite the overall lower nutritional value of local legumes compared to soybeans, extruded cowpeas with enzymes, or roasted pigeon peas, could improve bird production and gut health. The effectiveness of diatomaceous earth (DE), bentonite clay (BC) and turmeric (TUM) in ameliorating the toxic effects of aflatoxin B1 (AFB1) was assessed in growing chickens. Addition of AFB1 to the BD depressed (P<0.05) BWG and feed intake (FI) when compared to control chickens. The addition of BC to the AFB1 diet reduced the severity of the histological lesions caused by aflatoxins. Body weight gain (BWG), feed intake (FI) and feed: gain of chickens fed the adsorbents (BC or DE) alone were not different (P>0.05) from those of control chicks. In contrast, chicks fed the 2.0 mg AFB1/kg diet alone had significantly depressed (P<0.05) BWG and FI when compared to control chicks. Addition of 0.50 % BC did not improve (P>0.05) feed intake and growth rate of chickens fed the AFB1 diet. Chickens fed a control diet plus BC and either DE or TUM were as healthy as the control chicks. Bentonite clay gave a higher (P<0.05) body weight gain than the control chicks. Compared with chicks fed AFB1 alone, the addition of TUM into the AFB1 diet was not effective in preventing or reducing the increase in relative liver or kidney weight. Addition of a combination of both BC and TUM to the AFB1 diet prevented the increase in relative liver and kidney weights caused by AFB1. In contrast, the addition of a combination of DE and TUM to the AFB1 diet was not effective in reducing or preventing the increase in the weight of these organs caused by AFB1. Chickens fed the AFB1 diet supplemented with combinations of BC and TUM or DE and TUM had lower (P<0.05) concentrations of serum calcium compared to control birds but similar (P>0.05) concentrations of Alanine aminotransferase (AST), Gamma-glutamyltransferase (GGT), and uric acid (UA) to that of chicks fed AFB1 only. In conclusion the addition of TUM alone into the AFB1 diet also did not demonstrate an ameliorating effect. The addition of the combination of BC and TUM to the AFB1 diet was not as effective in reversing the effect of AFB1 on BWG as the combination of DE and TUM. When BC and DE were fed in combination with TUM, the results showed a reversal in the comparative individual effectiveness of BE and DE in their ameliorating effect on BWG.
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.
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.
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.
Mechanisms of resistance to Rhipicephalus ticks in Nguni cattle reared in the semiarid areas of South Africa.
(2013) Marufu, Munyaradzi Christopher.; Chimonyo, Michael.; Dzama, Kennedy.
Ticks and tick borne-diseases (TBD) are major challenges to cattle production among smallholder farmers in the semiarid areas of South Africa. Nguni cattle have been reported to be resistant to ticks and TBD, however, the mechanisms responsible for the trait are not fully understood. The broad objective of this study was to determine the mechanisms of resistance to ticks in Nguni cattle reared in the semiarid areas of South Africa. Tick infestation levels, body condition scores (BCS), packed cell volumes (PCV) and the molecular prevalence of A. marginale were determined in Nguni (n = 70) and local crossbred (n = 79) cattle reared in the semiarid areas of South Africa. Relationships among skin thickness, hair length, coat score and tick counts were assessed in seven to nine month old Nguni (n = 12) and Bonsmara (n = 12) heifers. As a follow up, cutaneous hypersensitivity responses to unfed larval extracts (ULE) of the ticks Rhipicephalus decoloratus and Rhipicephalus microplus were examined in heifers to determine host immunity to the ticks. Tick counts and inflammatory cell infiltrates in skin biopsies from feeding sites of adult R. microplus ticks in nine-month-old Nguni and Bonsmara heifers were also evaluated. The molecular prevalence of A. marginale was similar in the Nguni (47.7 %) and local crossbred (52.3 %) cattle. Nguni cattle suffered less severe losses from and were more vi resilient to A. marginale infection than local crossbreds. Nguni heifers had lower coat scores, hair length and tick counts than the Bonsmara heifers. The relationship between tick counts and coat score was positive and linear in the Nguni (y = 1.90x – 0.40) and quadratic in Bonsmara (y = -7.98x2 + 12.74x - 3.12) heifers. Bonsmara cattle showed a more intense immediate reaction and no delayed hypersensitivity reaction to ULE of Rhipicephalus ticks. Nguni heifers presented a less intense immediate reaction and a delayed hypersensitivity reaction at 72 h post inoculation with ULE of Rhipicephalus ticks. Reactions to R. decoloratus ULE produced a more intense skin response at all time intervals in both breeds than that of R. microplus. Parasitized sites in Nguni heifers had higher (P < 0.05) counts of basophils, mast and mononuclear cells than those in the Bonsmara heifers. Conversely, parasitized sites in Bonsmara heifers had higher (P < 0.05) neutrophil and eosinophil counts than those in the Nguni heifers. Tick count was negatively correlated (P < 0.05) with basophil and mast cell counts. There was a positive correlation between eosinophil counts and tick counts in both breeds, and between tick counts and mononuclear cell counts in the Bonsmara breed. It was concluded that smooth and short coats, delayed type hypersensitivity and cutaneous basophil and mast cell infiltrations are responsible for increased tick resistance in the indigenous Nguni cattle breed of South Africa.
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.
Relationship between linear type traits and fertility in Nguni cows.
(2014) Zindove, Titus Jairus.; Chimonyo, Michael.
The broad objective of the study was to determine the relationship between linear type traits and fertility in Nguni cow herds. Data collected from 300 Nguni cattle owning households from two municipalities (150 each) were used to compare trait preferences of Nguni cattle owners located in semi-arid and sub-humid production environments. A total of 1017 records from 339 cows of Venda, Pedi, Swazi and Makhatini ecotypes were used to investigate sources of variation of linear traits in Nguni cows of different ecotypes. A total of 1559 Nguni cows kept under thornveld, succulent karoo, grassland and bushveld vegetation types were used to determine the relationship between six linear type traits (body stature, body length, heart girth, navel height, body depth and flank circumference) and fertility traits (calving interval and age at first calving) in Nguni cow herds under natural rangelands. Relationships between the linear type traits and incidences of still births and abortions in Nguni cow herds were determined using 250 Nguni cows from two sites experiencing sub-humid and semi-arid environments (125 cows each). Cows with at least Parity 3 were used in the study. Nguni cattle owners located in sub-humid areas mostly preferred fertility traits (calving interval and age at first calving) whilst those from semi-arid regions preferred traits reflective of adaptation to harsh conditions. In sub-humid areas, calving interval (CI) and age at first calving (AFC) were ranked first and second, respectively. Although lowly ranked, linear traits were iv considered by communal farmers in selecting Nguni cows for breeding stock. Cow fertility problems were mainly experienced in semi-arid areas compared to sub-humid areas. Semi-arid areas had more households (32.7 %) with cows with extended CI (2 and 3 years) than sub-humid areas (19.1 %). Body depth, flank circumference and heart girth were influenced (P < 0.05) by parity of cow, season of measurement and body condition score (BCS). Body depth, flank circumference and heart girth increased with increase in parity of cow. Cows in Parity 7 had the deepest bodies and navels hanging closest to the ground. Venda cows had the same flank circumference and heart girth across all seasons (P > 0.05). Body stature, body length, heart girth, navel height, body depth and flank circumference varied with ecotype of cow (P < 0.05). Venda cows had significantly higher body depths. Cows with deeper bodies had navels near the ground (r = -0.32) and longer bodies (r = 0.46; P < 0.05). Cows raised on the succulent karoo rangelands had shortest calving interval, calved earliest, deepest bodies, widest chests and flanks. Linear type traits under study can be grouped into two distinct factors, one linked to body capacity (body depth, flank circumference and heart girth) and the other to the frame size of the cows (body stature, body length and navel height). Calving interval and age at first calving decreased linearly with increase of body capacity (P < 0.05). There was a quadratic increase in age at first calving as frame size of cows increased (P < 0.05). As the body depth increased the likelihood of the incidence of still births and abortions in cows decreased (odds ratios 1.15 and 1.15, respectively). It was concluded that small-framed cows with large body capacities had short calving intervals, calved early and were less likely to abort or experience still births.
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.
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.
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.
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.

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Browsing Doctoral Degrees (Animal and Poultry Science) by Author "Chimonyo, Michael."