South African Journal of Animal Science
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How does ewe age affect reproductive performance relative to rainfall conditions?
Get PDFWith climate change and its associated impacts on weather patterns being an inescapable reality, livestock producers will have to explore management and mitigation strategies to maintain production levels under adverse weather conditions. It is well-documented that ewe age affects reproductive performance, but it is unclear whether this phenomenon can be utilised to mitigate the effects of adverse environments. This study aimed to determine whether certain ewe age groups are better adapted to reproduce under specific rainfall conditions. Historical rainfall data collected on Tygerhoek Research Farm, South Africa, between 1975 and 2018 was used to group production seasons into five rainfall classes: dry, below average, average, above average, and wet. Ewe performance traits (conception rate, number of lambs born, number of lambs weaned, average birthweight, and average weaning weight) were calculated for each age group (2–6 years) across all seasons and within each rainfall class. Age group performance for each trait in each rainfall class was compared to the overall trend to see if any marked differences existed. Overall, reproduction rate was maximal at three to four years of age, and this trend was largely repeated for each rainfall class. Birthweight increased with age except in wet seasons, when no discernible trend was present, while weaning weight was highest in three- and four-year-old ewes. In dry seasons, however, there was a clear trend for weaning weight to increase as ewes aged. It was concluded that flock age structure cannot be used to mitigate environmental impacts if a flock is already structured to optimise reproduction.
(Submitted 25 October 2024; Accepted 5 August 2025; Published 07 November 2025
Could vitamin supplementation unlock the hidden potential of the indigenous Gerze chicken?
Get PDFIn this study, the broiler performance of Turkish Gerze chickens was investigated. One hundred and thirty day-old chicks were reared under intensive conditions until 20 weeks of age to examine whether administering a vitamin supplement via their drinking water would affect broiler performance. During this period, one group received the vitamin supplement, starting at four weeks of age, and the other (the control group) did not. At 20 weeks old, the chickens given the vitamin supplement had an average live weight of 1686 g and a feed conversion ratio of 4.47, while the control group was significantly lighter, at 1408 g, with a feed conversion ratio of 4.63. Dressing percentages were not significantly affected by vitamin supplementation, and averaged around 68%. The proportion of edible giblets also did not significantly differ between the two groups, contributing approximately 5%–6% of the carcass. The largest carcass component in both treatment groups was the legs, constituting 32%–33% of the carcass in males and 28% in females. Breast meat made up 22%–27% of the carcass, and this was not significantly influenced by vitamin supplementation. The pH and colour of the breast and leg meat were evaluated as meat quality traits, and these quality parameters were within acceptable limits for poultry meat for all groups.
Submitted 17 October 2024; Accepted 30 December 2024; Published January 20250.120
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Significance of research to South African science
The article explores how vitamin supplementation can improve growth and feed efficiency in the indigenous Gerze chicken. Although focused on a Turkish breed, it has relevance for South Africa by demonstrating how targeted nutrition can unlock the potential of local poultry breeds. This supports sustainable, small-scale farming and genetic conservation—key priorities in South African agricultural science
Lamb behaviour during and shortly after tail-docking
Get PDFRoutine husbandry procedures for lambs are increasingly scrutinised for their animal welfare implications. One such procedure is tail-docking, which is commonly performed to prevent breech blowfly strike. Although tail-docking is considered painful for lambs, the precise level of pain remains unquantified. While proponents argue that the long-term benefits outweigh the temporary pain caused; further investigations into the welfare implications of tail-docking are needed. This study assessed Merino lambs at an average docking age of 14 ± 3 days across five cohorts, each comprising 25–35 ewes and their lambs (n = 228). Two treatments were administered: the Control group lambs were left intact and undocked, while the Treatment group lambs were tail-docked. Lambs were randomly assigned to either group, with birth type and sex as stratifying factors. Observational data were collected during three periods: 1. during the tail-docking/sham procedure following the established protocol; 2. during a two-minute period immediately post-docking, upon returning to their dams; and 3. during a two-minute period 10 minutes post-docking. Signs of discomfort were evident during tail-docking and persisted at two and 10 minutes post-procedure. During the docking/sham procedure, undocked lambs were more likely to remain calm, whereas docked lambs exhibited signs of distress, including restlessness, kicking, bleating, and tense facial expressions. Observations at two minutes post-docking aligned with those recorded at 10 minutes post-docking, indicating sustained discomfort. These findings suggest that tail-docking results in both immediate and longer-term discomfort. Further research should assess whether the long-term benefits of tail-docking justify the associated pain.
Submitted 11 June 2024; Accepted 30 January 2025; Published March 2025
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Significance of research to South African science
The article makes a valuable contribution to animal welfare science in South Africa by providing empirical evidence on the behavioural responses of lambs subjected to tail-docking. Conducted at the Elsenburg experimental farm, the study uses a controlled design to assess short-term pain and discomfort associated with this common husbandry procedure. Its findings - highlighting signs of restlessness, agitation, and facial tension in docked lambs - offer scientific insight into the ethical implications of tail-docking, particularly for Merino breeds vulnerable to breech strike. This research supports ongoing discussions on welfare-friendly livestock management and aligns with global trends favouring ethical certification and traceability in animal product supply chains, directly informing South Africa’s sheep farming industry and policy development
The effects of monochromatic LED light from one to 14 days of age on the growth, muscle development, and blood parameters of goslings
Get PDFThis study was conducted to investigate the effects of monochromatic light on the growth performance, muscle development, and blood parameters of goslings from one to 14 days of age. A total of 192 male Sichuan White goslings were randomly assigned at hatching to four treatment groups of 48 birds, with six replications per group. These treatment groups were exposed to white light, red light, green light, or blue light in four environmentally controlled chambers. At 14 days of age, body weight and feed intake were determined on a per-pen basis, and one gosling per pen was selected for the collection of blood and muscle samples. All data were subjected to an analysis of variance. The results showed that the blue and green light groups had lower average daily feed intake and feed/gain ratios than the red and white light groups, but no differences in average daily gain and final body weight were found. Moreover, the leg muscle weight and leg muscle fibre diameter and density were unaffected by exposure to monochromatic light. Similarly, the goslings from the four treatment groups exhibited comparable plasma levels of growth hormone, insulin-like growth factor 1, immunoglobulin Y, and immunoglobulin M. Our study indicates that short-term exposure to different light colours does not affect the growth of goslings, but light with short wavelengths decreases feed intake and improves feed conversion efficiency.
Submitted 12 October 2024; Accepted 19 February 2025; Published March 2025
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Significance of research to South African science
The article contributes to the growing body of poultry science relevant to South Africa’s expanding interest in sustainable and efficient animal production systems. Although conducted in China, the study has significance for South African science by offering valuable insights into how controlled lighting environments - specifically the use of different monochromatic LED light colours - affect feed efficiency in goslings. The findings that blue and green lights improve feed conversion without compromising growth or health indicators can inform local producers and researchers exploring cost-effective technologies to enhance productivity in the early growth stages of geese and potentially other poultry species. This aligns with the country’s broader goals of advancing precision agriculture and improving animal welfare in intensive production settings
Artificial neural networks for predicting first-lactation 305-day milk yield in crossbred cattle
Get PDFoai:journals.assaf.org.za:article/23007This study was conducted using the first-lactation records of 1092 Vrindavani crossbred cattle to compare the relative efficiency of an artificial neural network (ANN) versus multiple linear regression for predicting the first-lactation 305-day milk yield (FL305DMY). The two input sets used for predicting FL305DMY in the study were input set-1: first four monthly test-day milk yields, age at first calving, and peak milk yield; and input set-2: first four monthly milk yields, age at first calving, and peak milk yield. The ANN was trained using a backpropagation algorithm based on Bayesian regularisation, and the algorithm was tested using four sets of training and test data at ratios of 66.67:33.33, 75:25, 80:20, and 90:10. The results revealed that the coefficient of determination showed no regular trend with decreasing the test dataset. Nevertheless, the observed values were highest for the 90:10 ratio of training-test data for both input sets, with the lowest root mean square error. The ANN model outperformed the multiple linear regression model when predicting FL305DMY, with an accuracy of 79.09% for input set-1 and 83.67% for input set-2, with the lowest root mean square error values for both input sets. Therefore, the ANN model can be used as an alternative technique to predict FL305DMY in Vrindavani cows.
Submitted 30 June 2024; Accepted 20 December 2024; Published January 2025
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Significance of research to South African science
The research demonstrates the potential of artificial neural networks (ANNs) to enhance dairy herd management through accurate early prediction of first-lactation 305-day milk yield in crossbred cattle. The study compares ANN and multiple linear regression models, showing that ANNs provide superior predictive accuracy and lower error margins. This has important implications for local dairy farming systems, particularly in data-limited environments, as it offers a practical tool for early identification of high- and low-producing cows. By enabling data-driven selection and culling decisions, the approach supports improved productivity, genetic progress, and economic efficiency in the South African livestock sector
Gut dysbiosis: Nutritional causes and risk prevention in poultry, with reference to other animals
Get PDFThe poultry gastrointestinal microbiome consists of more than 900 bacterial species and their metabolites; it serves as an indicator of bird health and is influenced by nutrition, medication, and other factors. Dysbiosis is a form of reduced microbial diversity, characterised by the loss of beneficial microbes, the expansion of opportunistic microbes, and the disruption of tight junctions, as well as raised pro-inflammatory cytokines (interleukin-6 and interleukin-17), tumour necrosis factor-α, and Enterobacteriaceae, and decreased short-chain fatty acids. Dysbiosis leads to various disorders, including liver disorders, metabolic disease, cardiovascular disease, and neurological problems. It also impacts several bodily systems, such as the gastrointestinal tract, kidneys, the gut-liver axis (liver disease, hepatocellular carcinoma, autoimmune liver disease, and metabolic-associated fatty liver disease), the gut-lung axis (pneumonia and chronic obstructive pulmonary disease), the gut-microbiota axis (irritable bowel syndrome, inflammatory bowel disease, and constipation or stool hardness), and the gut-islet axis (hypertension, hyperglycaemia, diabetes, and hypercreatinaemia syndrome). Many factors, including medications (antibiotics, anti-tumour, and immunosuppressants), environmental pollutants (heavy metals, pesticides, microplastics, and atmospheric particulates), high levels of nutrients (protein, fat, salt, and sugar), and others (age, disease, habits, and genes), cause and enable gastrointestinal dysbiosis to develop. Nutritional strategies such as the administration of probiotics, prebiotics, antibiotics, or phytogenic feed additives, and the consumption of a high-quality, balanced diet, as well as early detection of gut health malfunction and an emphasis on increasing bird resilience, can reduce the risk of dysbiosis, modify the gut microbial balance, and make microbial eubiosis possible.
Submitted 12 August 2024; Accepted 4 February 2025; Published February 2025
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Significance of research to South African science
The article by Salahi et al. (2025) is highly relevant to South African science as it addresses gut dysbiosis in poultry - a key concern for the country\u27s vital poultry industry. It provides comprehensive insights into how nutrition affects gut health, with implications for improving animal welfare, productivity, and food safety. By promoting non-antibiotic strategies, the paper supports sustainable agriculture and antimicrobial stewardship
The effects of supplementing prickly pear (Opuntia ficus-indica) powder on dairy calves’ health and growth performance
Get PDFThis study aimed to evaluate the effects of dietary prickly pear (Opuntia ficus-indica) powder and Lactobacillus supplements on calf growth and faecal pathogen counts. Prickly pear leaves were harvested, sun-dried for 14 days, and oven-dried at 105 °C, before grinding into a powder. Twenty-four female Holstein dairy calves (39.03 ± 0.75 kg live weight) were randomly assigned to each of the four treatment groups. The four treatments were: T1: the control group, calves fed a basal diet (milk plus calf meal), without supplementation; T2: calves fed the basal diet plus Lactobacillus at 5 g/day; T3: calves fed the basal diet plus prickly pear powder at 2.5 g/day; and T4: calves fed the basal diet plus prickly pear powder at 5 g/day. These treatments were applied from four days of age until weaning. Calf starter feed and clean water were provided ad libitum for the entire study period. The dietary treatments affected the feed dry matter intake, feed conversion ratio, average daily gain, weaning weight, faecal total coliform count, faecal Escherichia coli count, and faecal Enterobacteriaceae count, compared to the control group. It was concluded that the dietary supplementation of Lactobacillus or prickly pear powder improves feed efficiency and body weight gain, as well as reducing faecal pathogen counts in Holstein dairy calves.
Submitted 25 January 2023; Accepted 25 October 2024; Published May 2025
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Significance of research to South African science
The article “The effects of supplementing prickly pear (Opuntia ficus-indica) mucilage on in vitro ruminal fermentation of eragrostis hay” by Moshidi et al. (2025) is highly relevant to South African agricultural science, particularly in the context of sustainable livestock feeding practices. By investigating the use of locally abundant prickly pear mucilage as a natural additive to improve the digestibility of low-quality forage like eragrostis hay, the study addresses key challenges in ruminant nutrition under resource-constrained conditions. This research supports the development of cost-effective, drought-resilient feeding strategies that can enhance productivity while reducing reliance on commercial feed inputs. It aligns with national priorities around climate-smart agriculture and valorisation of indigenous plant resources for improved food security and rural livelihoods
Development and characterisation of a tambaqui (Colossoma macropomum) fish burger enriched with soy okara
Get PDFThis study aimed to develop and characterise a fish burger made from mechanically separated tambaqui (Colossoma macropomum) meat and incorporating soy okara as a functional ingredient. Four fish burger formulations were developed and the physicochemical characteristics (moisture, ash, lipid, protein, carbohydrate, and energy), instrumental colour parameters (L*, a*, b*, chroma, and hue angle), microbiological quality (facultative aerobic mesophiles, psychrophiles, moulds and yeasts, total coliforms, thermotolerant coliforms, Escherichia coli, coagulase-positive staphylococci, and Salmonella species), cooking characteristics, texture profile, and sensory traits of the tambaqui mechanically separated meat (MSM) and okara were analysed. Tambaqui MSM contained 78.18% moisture, 4.92% ash, 2.98% lipids, 12.47% protein, 1.45% carbohydrates, and 412.09 kcal energy/100 g. Okara contained 80.19% moisture, 3.48% ash, 3.90% lipids, 4.32% protein, 8.11% carbohydrates, and 417.00 kcal energy/100 g. The tambaqui MSM contained <10 most probable number (MPN)/g total and thermotolerant coliforms, and no E. coli or coagulase-positive staphylococci. The fresh okara contained 3.3 × 103 colony-forming units (CFU)/g facultative aerobic mesophiles, <10 CFU/g psychrotrophic bacteria when incubated at 7 °C for 7 days, 2.6 × 103 CFU/g moulds and yeasts, <10 MPN/g total and thermotolerant coliforms, and no E. coli. The intention to buy indicated that the tasters would buy the okara-enriched tambaqui fish burgers, and the fish burgers had good sensory acceptability, while the okara added nutritional value to the product. These results provide a promising option for making burgers using functional ingredients from by-products, as well as for adding value to the soy production chain by reducing waste.
(Submitted 21 June 2024; Accepted 17 September 2025; Published 30 December 2025
Nutrition of ruminant livestock grazing natural pasture, with special reference to supplementary phosphorus and sodium chloride – a South African perspective
Get PDFSouth Africa has a long history of studying specific dietary deficiencies in livestock grazing natural pastures (veld), with these pastures generally regarded as deficient in protein and phosphorus. The pioneering work by Sir Arnold Theiler and co-workers focused on addressing the cause of bovine botulism, but a direct link to an underlying phosphorus deficiency was later established. Other minerals have also received attention in South Africa, but since the early 1900s, the focus has mainly been on the phosphorus nutrition of grazing ruminant livestock. The initial focus on a primary phosphorus deficiency evolved and became the catalyst for renewed and comprehensive studies at Armoedsvlakte and elsewhere in southern Africa. The information obtained from these studies improved the understanding of the important roles and interactions between the selective grazing behaviour of ruminants and the composition of the veld, which serves as their primary source of daily nutrient intake. Supplementing grazing ruminants with various minerals and rumen-stimulating licks became routine practice, but results have varied and expected animal performance has not always been attained. This review provides a perspective of the nutrition of ruminant livestock grazing veld, with reference to the role of supplementary feeding, especially of phosphorus and the ever-present sodium chloride. Reference is also made to arthrosis or osteochondrosis, a phenomenon observed in grazing cattle since 1982.
(Submitted 09 July 2025; Accepted 16 September 2025; Published 04 November 2025
Nutrient composition of swill fed to peri-urban free-roaming pigs in Gert Sibande, South Africa
Get PDFPigs need a balanced diet for optimum physiology. We therefore investigated the nutritional composition of variably sourced swill fed to free-roaming pigs in Gert Sibande District Municipality, South Africa. Fourteen swill samples, originating from households, schools, restaurants, and wholesalers, were collected from pig producers in peri-urban areas. The samples were analysed for standard nutritional profiles, and mean outputs (descriptive and analytical statistics) were generated using the Statistical Package for Social Sciences. Overall, swill feeding strategies did not vary according to pigs’ age or physiological condition. The swill samples were high in moisture (household: 80.14%, school: 80.27%, restaurant: 54.36%, wholesaler: 56.63%), and low in dry matter (household: 19.86%, school: 19.73%, restaurant: 45.64%, wholesaler: 43.37%), compared to standard feeds. Excess crude protein and fibre contents and imbalanced macro-mineral compositions (calcium, phosphorus, and sodium contents) were observed. The moisture, dry matter, and crude fibre contents fell outside the recommended range. The crude protein, calcium, sodium, phosphorus, and ash contents were within the recommended range, but variances were wide, preventing standardisation. The significant variation in the composition of the swill samples has implications for pigs’ physiology, well-being, and general health. Swill feeding exposes pigs to vitamin and mineral deficiencies, hyperproteinaemia, increased vulnerability to infectious diseases, possible foreign bodies, and an inability to eat enough to meet the body’s nutritional requirements. Farmers should thus consider parboiling and dehydrating swill before feeding it to pigs as partial feed replacers, and pigs of ≤40 kg body mass should be fed a balanced ration, rather than swill.
(Submitted 18 June 2024; Accepted 8 April 2025; Published 22 September 2025