Masters Degrees (Animal and Poultry Science)

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The effect of varying dietary nutrient densities on performance: experimental investigations on the response of broiler chickens to different energy and lysine levels.
(2024) Ndlebe, Loyiso.; Ciacciariello, Mariana.; Tyler, Nicola Claire.
The overall objective of the study was to determine the influence of varying dietary apparent metabolizable energy (AMEn) and digestible lysine (dLys) inclusion levels on the overall growth performance of Cobb 500 broilers. Two experiments were conducted, and in each experiment a total of 1440 unsexed day-old Cobb 500 broiler chicks were randomly allocated to one of 48 pens (i.e. 30 chicks per pen) in a completely randomized block design. In experiment 1, the effect of incremental changes in dietary AMEn while maintaining a constant dLys: AMEn ratio was assessed. Experimental diets were formulated to contain eight different dietary AMEn concentrations ranging from 11.30 to 13.05 MJ/kg (+0.25MJ/kg) respectively, while adjusting dLys levels tomaintain a constant dLys: AMEnratio of 0.97. The broilers received a common broiler started diet for a period of 14 days, after which the experimental diets were introduced (Day 14-35 of the trial). Feed intake decreased linearly with incremental changes in dietary AMEn. Dietary AMEn intake and energy efficiency ratio (EER) differed significantly between treatments. Dietary AMEn increased linearly with incremental changes in AMEn, while EER exhibited a quadratic response. No significant differences in body weight gain (BWG) were observed for the entire treatment period (Day 14-35). According to the response curve equation (𝑌 = −58.952𝑥2 + 1473.9 − 6937.9), BWG was optimised at 12.55 MJ/kg. Increasing AMEn while maintaining the dLys: AMEn ratio improved feed conversion ratio (FCR), and significant differences occurred between the lowest and the highest nutrient densities. In experiment 2, the influence of varying dietary dLys levels in isoenergetic diets was evaluated. Experimental diets were formulated to contain eight different dietary dLys levels ranging from 0.95 to 1.30% (+0.05%). Dietary AMEn concentration was kept constant at 12.1 MJ/kg giving dLys: AMEn ratios 0.78, 0.83, 0.87, 0.91, 0.95, 0.99, 1.03 and 1.07. The broilers were fed a common broiler started diet for the first 14days, whereafter the experimental diets were fed from Day 14-35 of Experiment 2. Feed intake and AMEn intake were not affected by the incremental changes in dietary dLys. Energy efficiency ratio, dLys intake and digestible lysine ratio (dLysER) differed significantly between dietary treatments. Digestible Lys intake increased, while dLysER decreased with an increase in dLys inclusion level. Overall, BWG differed significantly between treatment groups, with an increasing quadratic response (𝑌 = −1119𝑥2 + 2871.7𝑥 + 301.11, 𝑃 < 0.05). Feed conversion ratio decreased (improved) linearly with increasing dLys levels. It can be concluded that broilers can sustain optimal growth performance in a range of dietary AMEn concentrations, provided that an ideal balance between dietary AMEn and nutrients is maintained. Furthermore, adjusting the dLys: AMEn ratio when feeding one dietary AMEn concentration for growing and finishing will optimise broiler performance. Keywords: broiler, digestible lysine, dietary energy, apparent metabolizable energy, energy concentration; digestible lysine: energy ratio; performance
Bone quality and incidence of urolithiasis in male broiler breeders fed a male or female ration.
(2024) Dube, Sithembisiwe.; Tyler, Nicola Claire.
Separate sex feeding is highly practiced in breeder farms as it gives a more targeted approach to nutrition, aligning the dietary requirements with the specific needs of male and female birds. Some breeder farmers give the female ration to male breeders as it saves having two feed silos per house and eliminates the chances of females receiving the wrong feed. However, the drawback is that the female ration contains high crude protein (CP), calcium (Ca), and phosphorous (P), which is more than recommended for male requirements. A total of 40 male broiler breeders fed a male-specific ration (MM), and 40 male broiler breeders fed a female ration (MF) at depletion were acquired from KwaZulu-Natal farms. Kidney weight (KW) and kidney lesion score (KLS) from euthanised male broiler breeders were examined as an indication of urolithiasis. Tibia bone weight (BW), bone thickness(BT), bone breaking strength (BBS), tibia ash% (TA%), organic matter (OM%) and Ca/P% were quantified to assess the effects of excess CP, Ca and P on bone quality. Data collected were subjected to a two-sample t-test at a 95% confidence interval using GenStat statistical analysis software, and principal component analysis (PCA) was performed using XLSTAT. The biplots from the PCA were used to predict correlation among the variables. The study results showed that the kidney weights of MF were significantly larger compared to MM (P<0.001). Kidney lesion scores were observed in 50% MF and were significantly higher than in MM (P<0.001). Significant differences in BW, BBS, TA%, and OM% were found between MM and MF. Bone thickness, and bone Ca%, P% and Ca/P% were not significantly different among the two groups. The findings suggested that high CP, Ca and P in female feed given to male broiler breeders can negatively affect kidney and bone quality. The results indicated a significant correlation between dietary composition, bone strength and the incidence of urolithiasis. The study concluded that the nutritional composition designed for female broiler breeders may not be entirely suitable for the physiological needs of male breeders, contributing to an increased susceptibility to urolithiasis. Also, high Ca can interfere with the absorption or retention of Ca and other minerals like P, resulting in low bone quality.
Economic optimum nutrition of growing pigs.
(2022) Pennicott, Chantel Gwen.; Gous, Robert Mervyn.
In two trials, a total of 504 boars and 504 gilts were used to determine the most profitable feeding strategy for the Topigs TN60 strain under current economic circumstances, using margin over feed cost as the objective function. The trials started when the pigs were 10 weeks old and were terminated after a 12-week trial period in each case. In the first trial the EFG Pig Model and Optimiser was used to assess the current feeding strategy used on the Baynesfield Estate, and to determine how the optimum strategy might change under different economic scenarios. An added objective was to evaluate the Pig Growth Model by comparing the predictions made by the model with the actual outcomes of the trial. Significant differences in gains, feed intake and carcass parameters were measured across sexes and feed treatments, and hence margin over feed cost, under the different economic scenarios applied. The Growth Model accurately predicted the optimum feeding strategy although the predicted feed intakes were marginally lower than those measured in the trial. The response to a series of feeds differing in balanced protein was measured in the second trial, the main objective being to develop equations that would describe the response of boars and gilts of this strain to dietary protein. These equations could then be used in the future to calculate the optimum economic level of dietary protein as economic circumstances on the farm changed. The results of both the simulation exercise and the trial provided strong evidence that the optimum economic level of dietary protein differs for gilts and boars, and that this difference widens as profitability in the enterprise is reduced, either through an increase in the cost of feed ingredients or when pork prices decline. Uniformity in body and carcass weight was increased with dietary protein content. The results of both trials provide convincing evidence that gilts and boars should be reared separately, and fed different dietary protein levels, if margin over feed cost is to be maximized, and that the economic optimum feeding strategy is not static but varies with economic circumstances.
Effect of balanced dietary protein on the physico-chemical quality and sensory attributes of rabbit meat from New Zealand white and Californian rabbits.
(2023) Makebe, Anela.; Rani, Zikhona Theodora.
The study was conducted at the University of KwaZulu-Natal, Ukulinga Research farm Pietermaritzburg, South Africa (SA) with the aim of investigating the effect of balanced dietary protein on physico-chemical quality and sensory attributes of New Zealand white (NZW) and Californian (CAL) rabbits. A total of eighty (80) NZW and CAL rabbits were allocated to a diet composed of six balanced dietary protein levels (T1 = 126g/kg, T2 = 143g/kg, T3 = 161g/kg, T4 = 178g/kg, T5 = 196g/kg and T6 = 213g/kg) at weaning age (35 days) for a period of 56 days. The rabbits were fed twice a day at 08:00 am and t 16:00 pm with water provided ad libitum. Meat quality traits which include pH, colour (L*, a* and b*), water holding capacity, cooking loss, shear force and drip loss were measured. No significant effects were found for pH values between the two breeds at pH45 and pH24. No significant differences were observed in colour (L*, a* and b*), water holding capacity (WHC), drip loss (DL), cooking loss (CL) and shear force values of meat. Sensory attributes of the meat from New Zealand (NZW) and Californian (CAL) were also evaluated using different tribes (Xhosa, Zulu and Shona), gender and ages with different cooking methods (cooking and frying). In this study, the first bite was rated superior (P < 0.05) in NZW breed for cooked meat. High scores were observed in overall flavour intensity for fried meat in NZW breed (P < 0.05). In relation to tribes, Shona tribe gave higher scores (P < 0.05) for both cooked and fried meat for all sensory properties. Age was observed to have a significant impact whereby the highest scores (P < 0.05) for sustained impression of juiciness from fried meat were given by respondents in age group 26-30 years. High sensory evaluation scores (P < 0.05) were observed in both females and males in fried meat than cooked meat for all sensory characteristics. Highest scores (P < 0.05) were detected in overall flavour intensity of fried meat in all tribes. The sensory scores for fried meat were significantly higher (P < 0.05) than cooked meat across age group between 21-25 and 26-30 years of age. It was concluded that the physico-chemical quality of NZW and CAL rabbits was not altered by the balanced dietary protein, 73 and consumer’s demonstrated to have a higher preferred fried meat than cooked meat based on the scores given by the respondents.
Prediction of milk yield using visual images of cows through deep learning.
Jembere, Lawrence.; Chimonyo, Michael.
The broad objective of the study was to determine, through deep learning, the predictability of milk yield from a cow's image data. The data size of 1238 image pairs (the side-view images and the rear-view images) from 743 Holstein cows within their first or second parity and the cows’ corresponding first lactation 305-day milk yield values were used to train a deep learning model. The data was first split into the training and testing data at the ratio of 80:20, respectively. The training data was then augmented four times more, then again split into training and validation data at the ratio of 80:20, respectively. Three principal analyses were done, i.e. the prediction of milk yield using rear-view images only, the prediction of milk yield using the side-view images only and the prediction of milk yield using a merge of the side-view and rear-view images (the combined-view images). In all three analyses, poor predictions were observed, i.e. R2 values of 0.32 for the model using the side-view image, 0.30 for the model using the rear-view images and 0.38 for the model using combined side and rear images. The mean absolute errors were 1146.4 kg, 1148.3 kg and 1112.9 kg for the side-view, the rear-view and the combined-view models, respectively. The root mean square error values were 1460.7 kg, 1480.5 kg and 1401.2 kg and the mean absolute error percentages were 17.6, 17.3 and 17.0 % for the side-view, rear-view and combined-view models, respectively. Hypotheses tests were also done to check whether there was any difference between these three prediction models. There was no significant difference in performance between all the prediction models (p>0.05), i.e. the side-view model, the rear-view model and the combinedview model. It was concluded that predicting 305-day milk yield of Holstein cows using either view has the same level of accuracy and no additional benefits are derived from using both the rear and the side views. Keywords: Computer vision; deep learning; linear conformation traits; 305-day milk yield; side-view images; rear-view images; combined-view images; Holstein cows.
The impact of quarrying activities and communal perceptions towards the environmental and animal welfare in the Ashburton community located in KZN Province, South Africa.
(2022) Mathe, Ntuthuko Cyprian.; Rani, Zikhona Theodora.; Mkhize, Ntuthuko Raphael.
The aim of this research was to evaluate the animal distribution, water quality, and how the communal residents perceive the quarry existence in the surrounding community. A qualitative survey in a form of semi-structured interviews was conducted among nine key informants out of 18 landowners at Lower Mpushini community, Msunduzi Municipality in the KwaZulu Natal, Province of South Africa. A larger sample number on the qualitative research approach diminishes the return, which is much more time consuming and costly. The results indicated mixed perceptions from the residents towards the impact of the quarrying activities and the existence of the quarry in the area. According to the results, the community appeared to be divided, with one side demonstrating negative perceptions and the others indicating positive perceptions towards the quarrying activities performed in the area. The impact of quarrying activities on river water quality neighbouring the quarrying mine which act as the source of water for animals in the surrounding area was also studied. A total of five water samples were collected (upstream, open pit, downstream 1, downstream 2, and downstream 3). The Water Quality Index (WQI) of both upstream and downstream sampling were found to have the same status of excellent water quality as the distance from the quarrying point increases. The levels that were acquired from the river water quality were in line with the South African National Standard (SANS) despite the fact that the quarry is suited to the banks of the river. The animal habitat use was studied over the period of 56 days of camera trapping at 20 sites that resulted in 1120 trap-nights with 2071 independent photos. According to the data that was collected from these photos, five species of antelopes Impala (Aepyceros melampus), Nyala (Tragelaphus angasii), Kudu (Tragelaphus strepsiceros), Wildebeest (Connochaetes), and Bushbuck (Tragelaphus sylvaticus) were identified to dominate the area with livestock kept inside the resident’s homesteads. However, only two species Nyala and Impala were considered as study animals, as they had naïve occupancy of ≥0.2 and the other species had naïve occupancy of ˂0.2. The naive occupancy for Nyala was 0.90 and for Impala it was 0.30. Nyala's average estimated site occupancy and detection were 0.90±0.05 (ѱ±SE) and 0.69±0.07 (p±SE) respectively. Impala average estimated site occupancy and detection 0.40±0.11 (ѱ±SE) and 0.77±0.04 (p±SE) respectively. The top model (deltaAIC=0) for Nyala species was psi (DH+No.T),p(DH+DW+DR) with the highest AIC weight of 0.098. The top model (deltaAIC=0) for Impala was psi (DH+BG+NoT), p(DR+BG+DH+NoT) with the highest AIC weight of 0.164. The results indicated that distance to the quarry (DQ) did not have a significant influence (p>0.05) on the presence or absence of the two-study species. Based on the findings of this research, it was concluded that there was no conclusive evidence that the quarrying activities have any negative impact on the well-being of the community, animals, and environment. However, more specific, and specialised research is advised to draw more solid scientific conclusions.
Response of growing rabbits in growth performance and carcass composition to balanced dietary protein.
(2023) Mathika, Zenande.; Gous, Robert Mervyn.; Rani, Zikhona Theodora.
The broad objective of the study was to measure growth performance and carcass composition of growing rabbits as influenced by the dietary protein levels. A 56-day feeding trial was conducted to measure the response of two rabbit breeds in growth performance and carcass composition to balanced dietary protein. A total of 72 sexed rabbits at the weaning age of 5-6 weeks were weighed upon arrival at the farm and randomly distributed singly to 72 grower cages of 61 x 60 x 58 cm. The breeds used were New Zealand White (NZW) and Californian (CAL) rabbits with equal numbers of males and females per breed. A representative sample of 8 New Zealand White rabbits was slaughtered before the beginning of the feeding experiment to estimate the initial carcass composition of the remaining NZW rabbits used in the response experiment. All the remaining rabbits were subjected to the experimental dietary protein treatments that were a result of blending low and high protein basal diets to produce four additional intermediate diets that resulted in a total of six experimental diets (126, 143, 161, 178, 196, 213g/kg). The trial was divided into two periods, from 1-28d and from 29-56d, respectively. Feed intake, body weight gain, and carcass composition were measured. At the end of the feeding trial, 48 rabbits (24 from each breed with equal numbers of males and females within each breed) were sampled for carcass analysis. These were analysed for moisture, ash, lipid, and protein content. Standard methods were used to determine the chemical composition of the rabbit carcasses. Appropriate regression models, including exponential, quadratic, and linear, were fitted to the data where relevant. The model with the best statistical fit was selected. Daily feed intake and final body weights were significantly influenced by the dietary protein levels (P < 0.05). Dietary protein did not influence feed conversion efficiency (FCE), (P > 0.05). The highest feed intakes, body weight gain, and consequently FCE’s were observed in the NZW breed. The NZW male rabbits exhibited highest feed intake and body weight gain while NZW female rabbits had the highest FCE. Significant interactions were detected in feed intake and body weight of the two breeds (P < 0.05). Female rabbits of the two breeds showed a significant interaction in feed intake and final body weight to the dietary protein levels. Moisture, ash, lipid, and protein in the carcass were not affected by the dietary protein content (P > 0.05). No significant (breed x sex) or (protein x breed x sex) interactions were observed in the carcass composition parameters. CAL rabbits had higher ash, lipid and protein and lower moisture contents than the NZW rabbits. Fat content was increased as the dietary protein content was reduced (P > 0.05). As a result, both males and females of the NZW breed had highest lipid contents on the lowest dietary protein level. CAL females and males had higher protein contents than NZW female and male rabbits, respectively. Carcass and pelt weights exhibited a significant response to the dietary protein levels (P < 0.05). Significant interactions in carcass and pelt weights were observed (P < 0.05). Considerable variation within treatments in all responses measured in this study meant that the responses to dietary protein could not be accurately described. Solutions to this problem would be to use more rabbits per treatment, to sample more rabbits per treatment, and to check on the accuracy of the laboratory analyses. Widening the range of dietary protein levels may result in a greater difference in the response of the rabbits to protein, thereby describing this response more accurately.
Integration of indigenous knowledge systems in sustaining water security for cattle in resource-limited communities.
(2021) Getyengana, Kamva.; Chimonyo, Michael.
The broad objective of the study was to assess the integration of indigenous knowledge systems in sustaining water security for cattle production in resource-limited communities. Cattle production in resource-limited communities contributes enormously to their everyday livelihoods however it is threatened by frequent occurrence of drought. A total of eight key informant interviews constituting of indigenous knowledge custodians between ages of >60 years old were conducted in Musina, Vhembe District Municipality, Limpopo and eight key informant interviews with indigenous knowledge custodians between ages of >60 years old were conducted in Umhlabuyalingana, Umkhanyakude District Municipality, KwaZulu-Natal, South Africa. Four focus group discussions with adult males and females, age >25 years and youth males and females, age =<25 years old. A total of 284 structured questionnaires were administered in two local municipalities of Limpopo and KwaZulu-Natal. In Umhlabuyalingana interviews listed the rejection of indigenous knowledge as a contributing factor to water security challenges. Water shortages forced cattle to travel long distances to water sources. Water security challenges cause weight loss, low productivity and mortalities. The integration of IKS into conventional methods was suggested in Umhlabuyalingana by elderly farmers unlike in Musina to assist curb water insecurity. Integration of indigenous knowledge systems (IKS) and conventional knowledge (CK) was encouraged in Umhlabuyalingana (11 %) as compared to Musina (1 %). Musina farmers preferred CK (25 %) over IKS. The odds of youth (P < 0.05) being open to the idea of integration of IKS and CK was seven times more than the adults. The association between cattle ownership and the use of IKS in Umhlabuyalingana differed (P < 0.01), farmers (35 %) that owned cattle used IKS more than farmers who owned cattle in Musina (18 %). Male farmers from Umhlabuyalingana (55 %) preferred to feed natural pastures during drought periods unlike farmers from Musina who preferred using commercial feeds and crop residues. Therefore, a study was conducted to assess the effect of using different cow-calf management systems on time budgets during droughts in Domboni village, Vhembe District, Musina. Four nondescript lactating cows from each management practice were used. Extensive managed cows spent 2.2 hours/day more (P < 0.05) walking to water points as compared to semi-extensive managed cows (0.7 ± 0.15 hours/day) during drought periods. Semi-extensive cows spent 3.4 hours/day more time feeding (P < 0.05) compared to extensive managed cows (47 ± 3.53 %). In conclusions drought poses as a threat to cattle and the lack of IKS use. Indigenous knowledge still has hope to upsurge and the youth is showing interest. The use of natural and crop residue for feed increases the possibilities of integrating IKS and CK. The semi-extensive management practices were viable for the cows as they travelled less and spent more time eating while extensive managed cows invested their time walking to water points and feeding points. Keywords: Distance, weight loss, low productivity, mortalities, youth, extensive, semi-extensive, feeding.
Perceptions of consumers, retailers and their attitude towards rabbit meat in the KZN province, South Africa.
(2021) September, Nolwandle.; Rani, Zikhona Theodora.; Gous, Robert Mervyn.
The broad objective of the current study was to determine the response and attitudes of consumers and retailers towards rabbit meat. Growth performance and the quality of rabbit meat as influenced by breed were also determined. A survey was conducted among 226 respondents (n=201 consumers and n=25 retailers) from two different municipalities under the uMgungundlovu district (Msunduzi and Richmond local municipalities), in the KwaZulu Natal province to investigate their perceptions and attitudes towards rabbit meat. Both rural and urban areas under the selected municipalities were visited. The results of the study showed that there was a positive association (p<0.001) between gender, consumption of rabbit meat, and willingness to purchase rabbit meat from butcheries and supermarkets. Out of the sampled population, sixty one percent (61%) of the consumers who had indicated to have never consumed rabbit meat before reported that rabbit meat is rare to find. Hence rabbit meat scarcity and lack of exposure were stated as the major reasons for the low consumption patterns and highlighted as the main reason why they have never consumed it. Only 8.6% of the respondents reported that it is against their religion to consume rabbit meat and a small portion (3.4%) of the population highlighted that they feel disgusted just by even the imagination of consuming rabbit meat. The results also revealed that out of the total interviewee’s, only two percent (2%) of the respondents indicated that they perceive rabbits as pets and not as the type of protein source that they would be prepared to consume. It was further observed that there was a strong significant association (p <0.05) between race and willingness to consume rabbit meat should it be made available in the retail stores. Furthermore, a large percentage (63.2%) of the respondents showed their willingness to purchase rabbit meat if it were to be made available in the local markets, whilst the remaining (33.8%) highlighted their lack of interest or willingness to purchase rabbit meat. There was a significant association (p<0.05) that was observed between occupation of the respondents and their willingness to purchase and consume rabbit meat. Out of the total number of retailers that were interviewed, twenty eight percent (28%) perceive that there could be a market for rabbit meat within the meat industry, whilst the remaining 72% reported that they do not see an opportunity/ market for rabbit meat in the South African meat industry. An on-station experiment was conducted to assess growth performance and rabbit meat quality whereby forty-eight rabbits from six different breeds (New Zealand white, New Zealand red, Californian, Chinchilla giganta, Cinnamon and American sables) were used. The rabbits were grown under the same conditions, fed a similar commercial pelleted diet from the weaning phase (35 days) and slaughtered when a commercial slaughter weigh of 2.5kg was reached. Feed and water were offered at ad libitum, with the following traits measured weekly: feed intake, body weight, average daily gain and feed conversion ratio. Following a feed withdrawal period of 12 hours, the rabbits were slaughtered and eviscerated. Carcass characteristics, physicochemical properties and growth performance were evaluated. The findings showed that there were significant differences between carcass characteristics of various breeds. Significant differences among dressing percentage were observed (p>0.01). No significant differences were observed for the pH values of the Longissimus dorsi between the different breeds at pH45 and pH24. Lowest pH values were observed after 24 hours post slaughter. Water holding capacity as a measure of the freshness of the meat is a vital meat quality attribute, significant differences (p<0.01) were observed between breeds for this characteristic. Meat from chinchilla giganta had the highest water holding capacity of 66% whilst New Zealand Red and Cinnamon had low water holding capacity of (59.7%) and (59.1%) respectively. The results indicated that breed had no significant effect on various carcass characteristics except for dressing yield of carcass. In conclusion, regardless of the production purposes of the breed (meat or fur) carcass and meat quality traits were similar.
Response in nitrogen balance, fibre digestibility and physicochemical characteristics of digesta in Windsnyer pigs fed on incremental levels of amarula nut cake.
(2021) Hlongwana, Fortunate Yenziwe.; Chimonyo, Michael.; Thomas, Ronald Sylvester.
The broad objective of the study was to determine the response in nitrogen balance, fibre digestibility and physicochemical characteristics of digesta in slow-growing Windsnyer pigs fed on incremental levels of amarula nut cake (ANC) based diets. Thirty clinically healthy growing Windsnyer pigs (21.5 kg ± 4.97) (mean ± standard deviation) were individually assigned to separate pens in a completely randomized design. Five iso-energetic dietary treatments were formulated to contain 0, 50, 100, 150, and 200 g/kg dry matter (DM) of ANC. Six pigs were fed on each experimental diet ad libitum. Pigs were given ten days of the dietary adaptation period. In Experiment 1, nitrogen (N) balance trial was conducted after thirty-one days of feeding pigs with an average body weight of 30.7 kg ± 6.57. The collection of faeces and urine took place every morning at 08h00 for five consecutive days. The hand-picking method was used to collect all faecal material from each pen and those captured by a 1 mm sieve suspended underneath the pen. Urine was collected using plastic trays and treated with 2 ml of sulphuric acid to reduce N volatilisation. The collected samples were frozen at -20 ºC pending analyses. Nitrogen intake (NI), total N excretion (TNE), urinary pH levels, N retention (NR), N absorption (NA), N digestibility (ND), N utilization (NU), net protein utilization (NPU), and biological value of feed protein (BVFP) were estimated. The average daily feed intake (ADFI), average daily gain (ADG), and gain: feed (G: F) ratio were also estimated weekly. There was a quadratic increase in ADFI (P < 0.05), while ADG (P < 0.05) and G: F ratio (P < 0.05) increased linearly with incremental levels of ANC. Nitrogen (N) intake increased linearly with ANC inclusion levels (P < 0.01). There was an increasing quadratic response in NA, apparent ND, and NR in pigs fed on increasing levels of ANC (P < 0.05). A positive linear response in NPU and BVFP to ANC inclusion was observed (P < 0.01). Nitrogen utilization increased at the rate of 0.63 g for each 1 g increase in ANC. There was a negative linear response in TNE through urine and faeces as ANC inclusion increased (P < 0.01). The relationship between urinary pH levels and ANC inclusion was described by the quadratic equation Y = 0.0115x2 - 0.3491x + 4.872 (P < 0.01). In Experiment 2, apparent total tract digestibility (ATTD) of fibre and physicochemical characteristics of colon digesta in growing Windsnyer pigs fed on ANC was determined. The experimental diets were blended with 3 g chromium oxide (Cr2O3) and pigs were acclimatized to this diet three days before the collection period. Representative feed samples for each diet were stored at room temperature pending Cr2O3 analysis. Faecal material was collected using the grab sampling method for five consecutive days between 08h00 and 13h00 and immediately chilled at -20 °C for further analysis. Digestibility of dry matter (DMD), acid detergent fibre (ADFD), acid detergent lignin (ADLD), hemicellulose (HemiD), and neutral detergent fibre (NDFD) were determined. After the digestibility trial, pigs weighing 34 kg ± 6.25 kg were fasted for 24 hours prior to slaughter, and routine abattoir procedures were followed. About 15 to 20 g digesta samples were obtained from the proximal colon and frozen immediately at -20 ºC within 1 hour of collection pending analysis. The DM content, pH level, water retention capacity (WRC), and swelling capacity (SWC) in the colonal digesta were estimated. The digesta pH was determined by inserting Crison 52 02 glass pH electrode immediately after collection. The WRC and SWC were measured using the centrifugation method and modified bed volume technique, respectively. There was a quadratic increase in DMD as ANC inclusion increased (P < 0.01). A positive linear relationship between HemiD and increasing levels of ANC was observed (P < 0.01). There was also an increasing linear response in NDFD as ANC inclusion increased (P < 0.01). Apparent digestibility of ADF and ADL increased quadratically in response to ANC inclusion (P < 0.01). There was an increasing quadratic relationship between digesta DM content and ANC inclusion (P < 0.01). The digesta pH level decreased quadratically with ANC inclusion levels (P < 0.01). The quadratic equation Y = -0.0017x2 + 0.0867x + 3.0929 and Y = 0.017x2 + 0.0389x + 2.9637 described the response in swelling capacity (SWC) (P < 0.01) and water retention capacity (WRC) (P < 0.05) to ANC inclusion levels, respectively. It can be concluded that dietary ANC improves N utilisation and fibre digestibility while reducing N excretion into the environment. Further, fibrous ANC increases the physicochemical properties of colonal digesta, predicting increased fibre fermentation. Hence, ANC can be a potential dietary protein source. Keywords: ammonia volatilization, by-products, digesta properties, dietary fibre, digestion, dry matter content, nitrogen absorption, nitrogen intake, nitrogen utilisation, swine, urinary pH level
Nature and level of trace mineral premix supplementation on growth parameters and mineral excretion in commercial broiler rations.
(2018) Franklin, Steven Bryan.; Ciacciariello, Mariana.
Commercial broiler premixes provide trace minerals (TM) such as Zinc (Zn), Manganese (Mn) and Copper (Cu) in excess of the birds’ requirements to maximize broiler performance (Untea et al., 2011). High inclusion levels of TM along with their low absorption in the GIT of the broiler, has led to increased levels of TM in their litter (Nicholson & Chambers, 2008; Manangi et al., 2012). Concerns have been raised about the accumulation of TM in the environment due to the high TM content of poultry litter. Two 35-day broiler trials were conducted at a broiler facility with 2880 day-old, Cobb 500 broiler males. Trial 1 evaluated whether decreasing inorganic trace minerals (ITM) levels (specifically Zn, Mn and Cu) in broiler diets would have a negative effect on broiler growth parameters such as body weight (BW), average daily gain (ADG), cumulative feed intake (Cum. FI) and feed conversion ratio (FCR). Zn, Mn and Cu were supplemented at 100%, 50%, 25% and 0% of the Cobb standards. Trial 2 tested whether broilers differed in their growth performance when supplemented with ITM, Organic (OTM) and Hydroxy (HTM) sources of TM (Zn, Mn and Cu) and which source would produce the least amount of TM in their excreta. No significant difference in Cum. FI and FCR was observed between the treatments in both trials for the first 21 days. On completion of Trial 1, no difference was observed in body weight between the PC, NC and 50% Cobb levels at day 35. In Trial 2 birds supplemented with HTM were 55g heavier (P<0.05) than those fed ITM at the same inclusion level at 35 days of age while those birds fed the PC, OTM and HTM showed no significant difference in their body weights. Providing broilers with HTM significantly reduced (P<0.05) Zn and Cu excretion at 35 days of age when compared to those diets containing ITM. From the study it was concluded that reducing TM levels or supplementing different sources of TM to broiler diets at lower levels showed no negative effect on broiler performance. The use of HTM significantly reduced TM mineral excretion of broilers. The results suggest that the use of HTM can maintain broiler performance while sustaining the environment.
In vitro fermentation and growth performance of merino lambs fed on umbrella thorn (Vachellia tortilis) leaf meal and sunflower oil.
(2019) Serumula, Mahlogonolo Daniel.; Nsahlai, Ignatius Verla.; Suinyuy, Terence Nkwanwir.
Forage legumes and vegetable oils are supplemented in ruminant diets to improve nutrient quality (energy density and crude protein content) and mitigating rumen gaseous emissions. The effects of both forage legumes and vegetable oils would depend on source, inclusion level and animal species. The broad objective of the study was to determine the effect of Vachellia tortilis leaf meal and sunflower oil on in vitro short-chain fatty acids (SCFAs) production, proportion of methane and growth performance of Merino lambs. The specific objectives of this study were to determine (1) the effect of Vachellia tortilis leaf meal and sunflower oil on in vitro total SCFA production, individual SCFAs composition, proportion of methane, carbon dioxide, and IVDMD; (2) the effect of Vachellia tortilis leaf meal and sunflower oil on growth performance of Merino lambs and (3) the effect of Vachellia tortilis leaf meal and sunflower oil on fractional outflow rate of particulate and liquid fractions of digesta in sheep. Five dietary treatments used were: the control diet (CT), Vachellia tortilis (VT) leaf meal diet (121.5 g/kg DM), sunflower oil (SFO) diet (40.8 g/kg DM), combination of Vachellia tortilis leaf meal and sunflower oil (VSFO) diet (63.4 g/kg + 19.5 g/kg DM) and maize grain – lucerne (ML) (300 g/kg + 180 g/kg DM) diet. Fresh samples were collected, dried in oven, ground and analysed for nutrient composition. Twenty-two duran bottles were incubated, including two blanks for 48 hours. Total SCFAs, acetate and propionate, acetate to propionate ratio, proportion of methane and carbon dioxide were not affected by the inclusion of Vachellia tortilis leaf meal and sunflower oil. Butyrate production and proportion of carbon dioxide were highest in VSFO diet at 16 hours compared to the control. In vitro dry matter digestibility (IVDMD) was higher in VT and VSFO diets compared to the control. The condensed tannin, ether extract and sunflower cake content did not influence production of total SCFAs, individual SCFA, proportion of methane and carbon dioxide. The high ether extract content in SFO diet negatively affected IVDMD. It was evident that inclusion of Vachellia tortilis leaf meal and sunflower oil did not affect production of total SCFAs, acetate to propionate ratio and proportion of methane. The proportion of methane was calculated based on stoichiometric method as observed and the Moss et al. (2000) equation. Both methods displayed a linear relationship with similar results. Ten mixed sex Merino lambs (n= 6) were fed on similar dietary treatments as in vitro fermentation study. An incomplete Latin square design was used where each treatment was represented by a random pair of lambs housed in individual pens for three periods (126 days). Lambs were offered 480 g/kg DM daily of dietary treatments with ad libitum accesses to urea-treated hay (Themeda trianda). For passage rate trial, five lambs were selected with one from each dietary treatment. The crude protein content was higher in VT and VSFO diets, due to inclusion of Vachellia tortilis leaf meal. Dry matter intake was lower in maize-lucerne diet compared to other diets including the control. Total dry matter intake (TDMI), average daily gain (ADG), feed conversion ratio (FCR) and neutral detergent fibre digestibility (NDFD) were similar across all dietary treatments. The inclusion of sunflower oil in dietary treatments negatively affected apparent digestibility, which was due to high ether extract content. Fractional passage rate, total mean retention time (TMRT) in both reticulorumen (RR) and hindgut (HG) of particulate and liquid fraction of digesta were similar across all dietary treatments. The improvement of roughage with a non-protein nitrogen source (NPN) provided a nutrient balance for lambs. The ether extract content in sunflower oil diets were above the recommended levels, thus possibly explaining the poor digestibility. In conclusion, the inclusion of Vachellia tortilis leaf meal and sunflower oil did not affect growth performance. The combination of Vachellia tortilis leaf meal and sunflower oil has potential to improve average daily gain.
In vitro assessment of selected ethno-medicinal plants as potential alternatives for the control of gastrointestinal nematodes in sheep and goats.
(2018) Mhlongo, Lindokuhle Christopher.; Nsahlai, Ignatius Verla.
Commercial anthelmintics are becoming ineffective against gastrointestinal nematodes (GIN) of ruminants due to development of resistant parasites. Research is exploiting anthelmintic ethno-medicinal plants for an alternative remedy. This study assessed the in vitro: (1) dose activity at different concentrations, (2) combined synergistic activity of ethanolic crude plant extracts on mixed GIN of sheep and goats; and (3) cytotoxic activity of these extracts on kidney vero cells. During assessment of in vitro dose activity, faecal samples of sheep and goats that were grazing on contaminated pasture were collected, cultured (12 days) to L3 larvae stage, and treated with 40, 20, 10, 5, 2.5, 1.25 and 0.25% v/v of Allium cepa, Ananas comosus, Bidens pilosa, Carica papaya, Crinium macowanii, Gunnera perpensa, Nicotiana tabacum, Ricinus communis, Sarcosterma viminale, Trema orientalis, Urtica dioica, Vernonia amygdalina, Zanthozylum capense, Zingiber officinale, Zizyphus mucronata and Aloe vanbalenii extracts. Larvae were subjected to Baermann technique for isolation and later observed under a microscope (10x objective). During the assessment of synergism at 1.25% v/v concentration (1:1), 28 crude plant extract combinations from eight (8) mostly edible plants namely: Allium cepa, Ananas comosus, Bidens pilosa, Carica papaya, Vernonia amygdalina, Zingiber officinale, Aloe vanbalenii and Nicotiana tabacum (inedible) were tested for their synergistic activity. The simple and Webb’s fractional product method were used to compute interactions of crude plant extract combinations. During assessment of cytotoxic activity MTT assay was used to assess effect of 16 individual plant extracts mentioned above on vero kidney cells. Results revealed that goats had a significantly higher efficacy than sheep at 40% (P=0.0253) and 20% (P=0.038) concentration (v/v); but goats had significantly lower efficacy at concentration (v/v) 1.25% (P= 0.0305) and 0.625% (P= 0.0158) relative to sheep. On the other hand, both goats and sheep had insignificant (P>0.05) efficacy for CPEs concentration (v/v) 10%, 5% and 2.5%. Plant species had no effect on efficacy at concentration (v/v) 40%, 20%, 10%, 5%, 2.5%, but had significant effect at lowest concentration (v/v) of 1.25 % (P=0.0085%) and 0.625 (P=0.0234%) which was not dose-dependent. Few plants had high activities at the lowest tested concentration (0.625% v/v). In goats it was Gunnera perpensa (89.47%±12.40), while in sheep Gunnera perpensa (100%±12.40), Urtica dioica (95.24%±12.40), Zizyphus mucronata (90.47%±12.40), Allium cepa (90.47%±12.40), Aloe vanbalenii (85.71%±12.40) and Bidens pilosa (80.95%±12.40). Interactions following Webb’s fractional product method were antagonistic and synergistic, whereas those following simple method yielded synergistic interactions only. In goats, V. amygdalina + Z. officinale (100%) was the most efficacious, while in sheep, A. cepa + C. papaya (100%), V. amygdalina + Z. officinale (100%), V. amygdalina + Z. officinale (100%) and A. comosus + N. tabacum (100%) were most efficacious. Animal species had a significant effect (P<0.001) on efficacy of combinations, efficacy was lower in goats (89.16%±0.95) relative to sheep (95.45%±0.095). Plant species did not affect (P>0.05) the efficacy of crude plant extract combinations. Vernonia amygdalina (IC50 = 0.01 mg/ml) followed by Zingiber officinale (IC50 =0.02 mg/ml) were the most cytotoxic crude extracts, while Allium cepa (IC50 = 0.27) and Aloe vanbalenii (IC50 = 0.22 mg/ml) were the least cytotoxic crude extracts. Cytotoxicity increased in a dose dependent manner. The concentration-cell viability relationship was negative linear in most crude plant extracts. While it was negative quadratic for Gunnera perpensa, Zingiber officinale and Vernonia amygdalina. Anthelmintic crude plant extracts are efficacious against GIN of sheep and goats. Although they are mostly harmless minimum effective concentration should be used. Crude plant extracts that were efficacious at the lowest concentration and observed synergistic crude plant extract combinations should be tested in vivo. Keywords: Anthelmintics, Animal species, Activity, Cytotoxic, Crude plant extract(s), Concentration, Ethno-medicinal, Gastrointestinal nematodes, Goats, In vitro, Plant species, Resistant, Sheep.
Response in antioxidant activity and shelf life of meat from broilers fed on incremental levels of Vachellia tortilis leaf meal.
(2018) Mthethwa, Nomalungelo.; Chimonyo, Michael.
The broad objective of the study was to determine the antioxidant activity and shelf life of meat from boilers fed on incremental levels of Vachellia tortilis leaf meal. One hundred and twenty Cobb-500-day old unsexed broilers were assigned in a completely randomized block design to six experimental diets containing 0, 30, 60, 90, 120 and 150 g/kg DM of Vachellia tortilis leaf meal. Each diet was offered ad libitum to 10 broilers in each pen, with a total of 12 pens. Each diet had one replicate. After overnight fasting and slaughtering of chickens, skinless and boneless chicken samples (breast and thigh) were collected, vacuum sealed and packed at 4°C until analysis. The determination of antioxidant properties in meat samples was measured using three assays; 2, 2-diphenyl-1-picryhydrazyl (DPPH), ferric reducing power (FRAP) and β-carotene-linoleic acid assay. The antioxidant activity using the DPPH model did not go beyond 50 % in all the inclusion levels. The FRAP assay exhibited a concentration-dependent linear response to the inclusion of V. tortilis leaf meal. The β-carotene-linoleic acid had the highest activity of 48.9 and 40.99 % recorded at 60 and 90 g/kg inclusion level respectively. The β-carotene-linoleic acid displayed a quadratic response, with the equation (𝑦𝑦=−0.0037𝑥𝑥2+0.7756𝑥𝑥+2.7811) showing 104.8 g/kg to be useful in improving the potency of natural antioxidants. Broiler breast and thigh samples were collected for the determination of shelf life. Drip loss (%) was measured after 24 hours of slaughter, meat pH, colour (L*, a* and b*), texture and v cooking loss (%) were measured at day 0, 7, 14 and 21 days. Broilers assigned to diets containing high levels of Vachellia tortilis leaf meal had tougher meat. High values of Warner-Bratzler Shear Force (WBSF) were recorded on day 21. Effect of leaf meal and days on texture had a linear response. High cooking loss results were obtained from the study, whilst there was no significant effect of leaf meal on the drip loss. The redness of meat had a quadratic response (𝑦𝑦=−0.0107 𝑥𝑥2+0.2779𝑥𝑥+6.145) over storage time. A period of not more than 13 days was found to be more ideal at retaining meat quality without development of lipid oxidation. An inclusion level of 94.5 g/kg of leaf meal improved the redness and yellowness of broiler breast and thigh meat samples respectively. In conclusion, Vachellia tortilis leaf meal can be incorporated in broiler diet up to 90 g/kg for improved storage time and antioxidant activity
Use of indigenous methods to control gastro-intestinal nematodes in chickens.
(2018) Majola, Nkanyiso Goodman.; Chimonyo, Michael.
Millions of resource-limited farmers depend on indigenous knowledge (IK) to sustain chicken health. The level of understanding on these IK systems is low. The objectives of the study were to: (1) explore IK used to control gastro-intestinal nematodes in chickens; (2) assess the extent of use of IK to control gastrointestinal nematodes (GIN) in chicken and to (3) evaluate the efficacy of selected medicinal plants used by farmers to control GIN in chickens. The study was conducted in the Jozini local community. Indigenous knowledge is sourced from parents, forefathers, knowledgeable community members through oral communication. Medicinal plants are prepared using different methods such as boiling and soaking in water. Chickens are dewormed after displaying clinical symptoms of GIN infestation. Birds take a maximum of three days to recover after treatment. Male farmers were 3.968 times likely to be using IK than females. Male farmers were more cultural and depended on IK more than females. Farmers owning larger flock sizes were 8.196 times more likely to use IK than farmers with small flock sizes. Resource-limited farmers were 1.701 times likely to use IK than less-poor farmers. Famers owning cattle were 1.998 times likely to use IK than farmers not owning cattle. The extent of use of IK was influenced by demographics and the availability of medicinal plants. The medicinal plants tested in Trial 3 were Gomphocarpus physocarpus, Cissus quadrangularis and Aloe maculata. These were the popular plants used in Jozini. Birds on the control had higher mean faecal egg count (FEC) (321.3) of than Gomphocarpus physocarpus (270), Cissus quadrangularis (185) and Aloe maculata (155). These results showed that the selected medicinal plants have anthelmintic potential and needs to be promoted. Keywords: medicinal plants, gastro-intestinal nematodes, anthelmintics, faecal egg counts.
Effects of water availability on physiological status of Nguni does and weaners.
(2018) Mseleku, Cresswell.; Chimonyo, Michael.
Physiological status of goats is mainly affected by the availability of feed and water. Factors such as frequency of droughts and low rainfalls are main contributors to water scarcity. Understanding perceptions of goat farmers about water availability in the aspect of climate change is vital for sustainable and improved livelihoods. The objectives of the study were to: (1) determine the factors influencing water availability for Nguni goat flocks in wet and dry areas; and (2) compare responses in physiological status of Nguni weaners and does to distance from water source. Farmer perceptions were captured from 300 goat farmers using structured questionnaires. Water shortage was among the major constraints to goat production. The odds ratio estimates of households experiencing goat drinking water shortage were high for temperature and rainfall patterns (P<0.001). Goat flock size and distance from water sources highly predisposed the household to experience water shortage. Farmers who did not provide additional drinking water for goats were 3.7 times more likely to have goats experiencing water shortage as compared to farmers who provided additional drinking water for goats (P<0.01). Goats that were owned by farmers situated (≥1 km) away from the water source were 1.89 times more likely to experience water shortage compared to goats owned by farmers situated (<1 km) from the water source. Farmers who had large goat flock size were 1.64 times more likely to experience water shortage as compared to the farmers who had small goat flock size (P<0.05). A trial was conducted to compare physiological status responses of Nguni weaners and does to distance from water sources. A negative linear regression was recorded between body condition score and distance from water source. A positive linear regression was recorded between FAMACHA scores and distance from water source across weaners and does. The rate of reduction in body condition scores were lower in does (-0.45 ± 0.292) as compared to weaners (-0.55 ± 0.374). The FAMACHA scores increased as distance to water source increased in both classes of goats. The slope was, however steeper (P<0.05) for does (0.56 ± xiv 0.403) than for weaners (0.44 ± 0.432). There was a negative linear relationship between packed cell volume and distance from water source. Reduction in packed cell volume was lower (P<0.05) in does (-0.62 ± 2.57) as compared to weaners (-11.21 ± 2.196). The rectal temperature and distance from water source were positively related. The increase in rectal temperature was lower (P<0.05) in does (0.05 ± 0.280) than in weaners (0.07 ± 0.432). It was concluded that although both classes of goats were affected by the distance to water source, the effects were more adverse in does than in weaners
Effects of essential oil, probiotic, palm kernel fatty acid distillate, optigut, or sunflower whole seeds as alternatives to antibiotic growth promoters on broiler performance.
(2019) Tshonaphi, Caswell Sifiso.; Ciacciariello, Mariana.
The increasing consumer and legislation pressure to phase out the antibiotic growth promoters (AGPs) in the broiler industry has prompted researchers to find suitable alternatives to AGPs that will improve broiler performance at levels comparable to AGPs. There were three trials that were conducted in the present study. The aim of the first trial was to evaluate the effects of supplementing broiler diets with Oligo essential (essential oil) or AGPs on growth performance and caecal Clostridium perfringens (C. perfringens) counts of broilers from 0 to 33 days of age, reared in a commercial farm. A total of ten broiler houses were used for the trial. Five houses were designated for broilers receiving feed supplemented with AGPs and other five houses for broilers receiving feed supplemented with Oligo Essential. The houses were used as experimental units. The control houses (1, 2, 3, 4, and 5) were paired with trial houses (7, 8, 9, 10, and 11). The chicks placed in paired houses had the same parent flock age, were placed on the same day and also slaughtered at the same age. A total of 300 000 day old broiler chicks (Cobb 500) of mixed sex were used in the trial and the stocking density per house was 22.10 birds/m2. In the period of 0 to 33 days of age, it was observed that the broilers that were fed diets supplemented with Oligo Essential had a significantly poorer feed conversion ratio (FCR) and higher feed intake (FI) when compared to broilers that were fed diets containing AGPs. However, no effect of dietary treatment was seen on the body weight (BW). The caecal C. perfringens counts at 9 and 30 days of age were unaffected by dietary treatment. In conclusion, supplementing broiler diets with Oligo Essential had negative effects on broiler performance in the present study. In the second trial, the objective was to determine the effects of Lactobacillus based probiotic or AGPs on broiler performance in a commercial farm. A total of six broiler houses were used for the trial. Three houses were designated for broilers receiving feed supplemented with AGPs and other three houses for broilers receiving feed without AGPs, but all the day-old chicks were sprayed with Lactobacillus based probiotic at the hatchery. The dosing volume was 10ml per 100 chicks. The houses were used as experimental units. The control houses (1, 2, and 3) were paired with trial houses (4, 5, and 6). The chicks placed in paired houses had the same parent flock age, were placed on the same day and also slaughtered at the same age. A total of 180 000 day old broiler chicks (Cobb 500) of mixed sex were used in the trial and the stocking density per house was 20.80 birds/m2. It was noted that there was no significant difference in BW, FCR, FI and mortality between the treatments at 33 days of age. Therefore, it was concluded that the Lactobacillus based probiotic demonstrated feasibility of being a substitute for AGPs as the broiler performance was comparable to broilers that received diets supplemented with AGPs. In the third trial, the objective was to investigate the effects of Optigut, palm kernel fatty acid distillate and sunflower whole seeds on broiler performance, organs weights, intestinal length, digesta pH and caecal microbial profile. A total of 3360 Cobb 500 day old broiler chicks were randomly distributed into 48 pens. There were six dietary treatments for the trial: (i) Negative control with no AGPs; (ii) Negative control supplemented with AGPs; (iii) Negative control supplemented with Palm kernel fatty acid distillate at 2.5%; (iv) Negative control supplemented with Optigut at 0.4% in the starter, 0.2% in the grower and 0.1% in the finisher; (v) Negative control supplemented with Sunflower whole seeds at 4.0%; (vi) Negative control supplemented with Palm kernel fatty acid distillate (2.5%) and Sunflower whole seeds (4.0%). It was observed that there was no significant treatment effect on broiler performance parameters, organs weights, intestinal length, digesta pH and caecal microbial profile at 35 days of age. The results of the study suggest that the trial was conducted in a hygienic environment, therefore, it was recommended to conduct challenge studies to further investigate the effects of these alternatives to AGPs.
Use of inert markers to predict diet composition, forage intake, digestibility and passage rate in sheep.
(2019) Pepeta, Bulelani Nangamso.; Nsahlai, Ignatius Verla.; Hassen, Abubeker.
The mechanisms that regulate intake and composition of selected diets in ruminants are complex and vary among animals of the same species and cross species. These are governed by highly variable aspects, which range from animal factors to physio-chemical properties of feeds. Understanding how ruminants select their diets is imperative to improve their utilisation of feed resources regarding the diversity of plant species that can be used as their sources of feed. The objectives of the study were to: (1) determine the effect of group feeding and removal of dietary ingredient (Sorghum bicolor) on diet selection, nutrient and total dry matter intake, and digestibility in choice-fed sheep; (2) asses the effect of animal stocking rate on dry matter and nutrient intake, botanical composition, nutrients selected, total tract digestibility and passage rate of diet consumed by sheep; and (3) predict dry matter and nutrient intake, botanical composition, nutrients selected and total tract digestibility using inert markers. Twelve sheep (mean weight: 29.7 ± 4.63 kg) were assigned to three treatments. In treatment one, five feeds were fed to sheep fed as a group of 9 sheep (G). In the second treatment, five feeds were fed to sheep penned in isolation (I) and in the last treatment, four feeds with sorghum stover (SS) removed were fed to sheep penned in isolation (R). There were five experimental feeds: veld hay (VH), sorghum stover (SS) and maize stover (MS) fed ad-libitum, and Lucerne hay (LH) and bean straw (BS) fed at restriction levels of 0.15 and 0.35 kg/day per sheep, respectively, in a group or individually fed sheep. Diet compositions were similar (p >0.05) between sheep fed individually with or without SS. Similarity in proportion of these dietary ingredients consumed between R and I may be due to less selection of SS; therefore, its removal did not significantly influence consumption and selection of other dietary ingredients. Group feeding of sheep relative to individual feeding with similar dietary ingredients influenced selection of SS. Sheep fed individually had lower intake levels of SS. Establishment of a dominance hierarchy in group-fed sheep may have caused dominant animals to feed on poor quality stovers just to prevent sheep lower in the hierarchy from eating resulting in high consumption of stovers. Fifteen sheep (mean body weight 46.5 ±3.3 kg) were blocked by weight into four groups and each sheep was randomly allocated to four stocking rates (treatments) of 1, 2, 4 and 8 sheep per pen and fed: MS, SS, and VH. All feeds were fed on separate feeding troughs ad-libitum. To evaluate the effect of animal stocking rate (SR) on passage rate of digesta, one sheep each from stocking rates one (SR1) and two (SR2) animals per pen and two sheep each pair from stocking rates of four (SR4) and eight (SR8) animals per pen were randomly selected and dosed with Ytterbium (particulate) and cobalt-ethylenediamine tetraacetic acid (Co-EDTA; liquid) markers. An optimisation procedure was used to predict diet selection by minimising the sum of the squared discrepancies between the proportional concentration of markers (acid insoluble ash: AIA, modified acid detergent fibre: MADF, and acid detergent lignin: ADL) in faeces (A) and their proportional concentration in dietary components (E) (MS, SS and VH), corrected for faecal recoveries of markers. Fractional passage rate (liquid and particulate) from both the rumen and in the hind gut, mean retention time, and total mean retention times across treatments were similar (p >0.05). Similarly, intake of dietary ingredients, nutrients (crude protein: CP, neutral detergent fibre: NDF and acid detergent fibre: ADF), total dry matter intake and composition of diets selected were not different across treatments. Selectivity index factors of diets selected were all within the range of 1.56-3.80, which reflected that animals were able to retain the diets they selected long enough in the gastro intestinal tract (GIT) for efficient digestion. Total tract digestibility and mineral intake (Ash) differed (p <0.05) in relation to animal stocking rate. Sheep in SR2 had the highest digestibility and consequently increased dry matter intake. Predicted dry mater intake and total tract digestibility of a diet selected by sheep were less sensitive to correction of incomplete faecal recovery of the markers and they tended to be similar to observed dietary parameters. Therefore, inert markers can be used to predict several components of a diet selected by grazing sheep and other classes of ruminants.
Response in carcass yield, organ weights and the gut morphology to Vachellia tortilis inclusion in broilers.
(2018) Miya, Angelique.; Chimonyo, Michael.
The broad objective of this study was to determine the response to incremental levels of Vachellia tortilis leaf meal on carcass yield, organ weights and gut morphology of broilers. Five-hundred unsexed cobb 500-day-old broiler chicks were fed on conventional starter mash for 14 days. The chicks were randomly allocated to six dietary treatments. These treatments contained 0, 30, 60, 90, 120 and 150 g/kg DM inclusion levels of Vachellia tortilis leaf meal. Each diet was offered ad libitum to 10 birds per pen for 17 days before they were slaughtered. Six pens received the same experimental diet. There was a linear decrease in both slaughter weight (SW) and dressed carcass weight (DCW) (P<0.05) as V. tortilis leaf meal increased. The SW and DCW decreased by 0.77 and 0.94 g for each g/kg increase in V. tortilis inclusion. The scaled weights of thighs (TW) and drumstick (DW) showed no relationship with levels of leaf meal. The weight of gizzard, intestines and stomach, however, increased linearly (P<0.05) as levels of leaf meal increased. Relative gizzard, intestine and stomach weights increased by 0.0028, 0.0059 and 0.0008 g for each g/kg increase in Vachellia tortilis (P<0.05) inclusion. There was a linear increase in relative heart weight and kidney weight with increasing levels of V. tortilis leaf meal in the diet. The relative heart and kidney weight increased by 0.0009, 0.0006 g as V. tortilis increased (P<0.05). The relative weight of the liver was, however, not related to V. tortilis inclusion. It was concluded carcass yield and organ weights responded differently to increase in Vachellia tortilis inclusion. There was a linear increase in villus height (VH), apparent villus surface area (AVSA) and villus height: depth ratio (P<0.05) as V. tortilis leaf meal increased. The VH, AVSA and CD/VH ratio increased by 0.12, 1.08, and 1.96 g for each g/kg increase in V. tortilis inclusion. The crypt depth (CD) showed no relationship (P>0.05) with levels of leaf meal. The thickness of submucosa, muscularis and epithelial, however, increased linearly (P<0.05) as levels of leaf meal increased. Submucosa, muscularis and epithelial thickness increased by 8.73, 1.15, and 0.38 g for each g/kg increased in Vachellia tortilis inclusion. Elevated inclusion levels of V. tortilis leaf meal was associated with increased villus height, apparent villus surface area, villus height and depth ratio, thickness of submucosa, muscularis and epithelial. In conclusion, increasing V. tortilis in the diet increase gut morphology parameters of broiers thus improve the digestibility and absorption with a negative effect on growth performance, carcass yield and internal organ weights.
Distribution, phenotype and factors influencing the production potential of Nguni sheep.
(2018) Oosthuizen, Peter Andrew.; Laing, Mark Delmege.; Van Zyl, Erika A.
The Nguni sheep of South Africa is an indigenous breed that is adapted to its environment. Migrating from Central Africa down the sweltering east coast of Africa down to Southern Africa, the sheep were exposed to different diseases. Survival of the fittest was synonymous with the breed, resulting in a breed harmonized with its environment. Nguni sheep that formed a part of this migration ended up as a remnant of the original sheep in KwaZulu-Natal. The sheep have been in South Africa for hundreds of years and the breed is primarily recognized by its geographical environment and by the people keeping the sheep than by breed herd books and breed societies. Conservation of the breed is important, but the sheep has to perform competitively with other breeds of sheep, and empirical research is needed to identify its superior characteristics. A survey was done in KwaZulu-Natal to locate Nguni sheep owners and to complete a questionnaire regarding their management and challenges. During the survey process, 52 farmers were found in four prominent agro-ecological zones in KZN, with a total of 1184 sheep. The largest flocks were found in the Ingwavuma zone with 347 animals among 11 owners. One of the primary management problems identified was the frequent death of lambs. Previous work with this breed suggests that this is often caused by gastro-intestinal nematode infection in young lambs. Reasons furnished for keeping the sheep was mostly for extra income and home consumption. The perception exists that the Nguni sheep does not compete with industrial sheep breeds such as the Dorper in terms of mutton production and therefore crossbreeding with Dorper and Merino is being practiced to improve the carcass quality of offspring. As a result, the original breed is now endangered and decisive efforts will have to be made to protect the pure Nguni sheep genome. Little is documented about the characteristics of the sheep, but many anecdotal concepts exist, defining what the phenotypic characteristics of the Nguni sheep should be. These characteristics were assessed by measuring traits such as heart girth, shoulder height, pelvis width, ear length and tail width. The measurements and observations were taken using the Nguni sheep flocks from the Dundee and Makhathini Research Stations. The Research Stations are situated in widely different bioclimatic regions, and the management of the two flocks differs also (intensive versus extensive). However, the original flocks are related because the Dundee flock was obtained from Makhathini in 2009. In the intervening nine years, measurable differences between the two flocks have developed. To investigate their performance when exposed to good and poor feed quality, the performance of Nguni sheep was examined under good (grazing maize) and poor (winter veld) nutritional circumstances. Merinos were used as a comparative breed. The Merino sheep were roughly double the size of the Nguni sheep. In this trial there was no significant difference (P>0.05) regarding lactating ewe performance within the nutritional treatments. There were also no significant differences (P>0.05) in the lamb growth within treatments between the breeds. Regarding ewe efficiency, the Nguni sheep ewes were more efficient over treatments than the Merino ewes. This data lead to the conclusion that the Nguni sheep has production comparable to that of the Merino. Under conditions of nutritional stress Nguni sheep tend to outperform Merino sheep. The final trial was to determine the relative levels of resistance or susceptibility of Nguni and Merino weaner lambs to gastrointestinal nematode (GIN) infection. This trial was done using lambs that were weaned from the winter trial mentioned above. They were placed on either Kikuyu or veld pasture for the summer. Faecal egg count (FEC) was to measure the level of GIN infection on the two different forages (as it is postulated that the inoculum level of GINs will be higher on the dense, humid environment in the Kikuyu). FEC indicated a significant difference (P<0.05), between the breeds, but there was no significant difference (P>0.05) between the two forage treatments. However, the Nguni weaner lambs in poor body condition could withstand GIN infection better than the Merino weaner lambs. An overall observation from the feeding trials was that if nutritional stress was removed, the Nguni sheep performed as well as an industrial sheep breed such as the Merino, although the mean Nguni live mass was approximately half that of the Merino weaners. The challenge for the future of the Nguni breed is to make the breed commercially attractive, i.e., with larger forequarters and hindquarters, without diluting the genome and losing the positive traits of the pure Nguni sheep. A cross with the Dorper breed, followed by back-crossing back to the Nguni parentage for seven generations, could be used to achieve this, with less than a 1% dilution of the genome. A detailed DNA fingerprint of the pure Nguni genome could be used to confirm the process.

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