South African Journal of Animal Science
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Behaviour of commercial layer hens in enriched cages and floor systems examined using human and video-based observations
Get PDFThere is considerable pressure to eliminate the use of conventional cages in commercial layer hen production systems. However, the assessment of alternative systems that can ensure the hen’s ability to perform natural behaviours, while simultaneously enhancing farm productivity and economic efficiency, remains incomplete. This study assessed layer behaviour in a floor system and in enriched cages on a commercial layer farm using human and video-based observations. The study focused on dust bathing, nesting, feather pecking, and perching behaviours, and on the formation of mud balls on the feet. A large proportion (72.9%) of the hens exhibited dust-bathing behaviour, with an average duration of 22.63 minutes. Feather pecking was exhibited by 35.4% of layers in the enriched cages, compared to 58.3% of layers in the floor system. Overall, feather pecking was the least observed behaviour. Layers in enriched cages used perches more (47%) than layers in the floor system (27%), and a negative association was found between body weight and perching in layers in the floor system. At the end of the six-week trial period, 41.67% of the hens had developed mud balls on their toes that exceeded 3 cm in length. The results of this study provide evidence of the relationships between poultry behaviour, welfare, and production. Video-based observations confirmed that farm managers may not be able to identify certain welfare-related behavioural aspects unless they are closely monitored. The results of this study may be used to inform stakeholders about behaviour and welfare considerations in the management of commercial layers.
Submitted 28 August 2024; Accepted 27 January 2025; Published March 2025
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Significance of research to South African science
The article contributes meaningfully to the advancement of animal welfare science in South Africa. It represents the first field-based study in the country to comprehensively assess layer hen behaviour under commercial farming conditions using both human and video-based observation techniques. By analysing welfare indicators such as dust bathing, perching, feather pecking, and nesting behaviours, the study offers crucial evidence on how different housing systems affect hen welfare and productivity. These insights are particularly significant as South Africa navigates global pressures to transition away from conventional cages toward more humane and sustainable egg production systems. The findings inform policymakers, producers, and animal welfare advocates, supporting evidence-based decisions for improving poultry housing standards and aligning with both local industry realities and international welfare trends
Use of a continuous disinfection programme in commercial broiler production
Get PDFThe growing threat of antibiotic resistance necessitates the development of novel methods for addressing health management in animal production and reducing dependency on antibiotics. Biosecurity is a term that describes the various measures taken to reduce the introduction or proliferation of infectious material in the growth environment. Cleaning and disinfection are commonplace in broiler production; however, after chick placement, few further interventions are available to address possible negative health effects. In this study, a continuous disinfection programme using a modified quaternary ammonium compound-based disinfectant for drinking water application and direct spray was trialled at a commercial scale. The study evaluated two cleaning and disinfection protocols in four commercial poultry houses of 1800 m2 each in Stutterheim, in the Eastern Cape. Over two non-consecutive growth cycles, two houses underwent a standard cleaning and disinfection protocol (organic removal, pressure rinsing, surfactant foam, and aldehyde disinfectant), while two houses followed a continuous disinfection programme (Virukill®-based disinfection, followed by periodic mist spraying and waterline dosing). The test evaluated whether the compound could improve growth performance and mortality rates. The product may be a viable alternative to standard chemicals currently used in the industry for cleaning and disinfection, as the use of the continuous disinfection programme resulted in improved performance. The results further indicated that improved cleaning, as evaluated using viral methods, could serve as an indicator of performance.Submitted 22 June 2024; Accepted 23 June 2025; Published 18 July 2025
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Significance of research to South African science
The article “Use of a continuous disinfection programme in broiler farms and its effects on litter microbiota and bird performance” by Beauzec et al. (2025) is significant for South African science as it contributes to improving biosecurity and productivity in poultry farming - one of the country’s most important animal protein sectors. The study demonstrates how continuous disinfection affects microbial populations in litter and enhances broiler growth performance and feed conversion. These findings are especially relevant in South Africa’s context of rising demand for safe, efficient poultry production under conditions of disease pressure and environmental challenges. The research offers evidence-based strategies for enhancing food safety, animal health, and farm hygiene, which are key to sustainable and competitive poultry systems in the region
Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics
Get PDFHeat stress has been identified as one of the major challenges for livestock production. Global temperatures are steadily increasing, with South African temperatures increasing at nearly twice the global rate. Of the livestock used for food production, dairy cows are the most sensitive to thermal changes, which have detrimental effects on their health, welfare, and overall productivity. Several abiotic factors that influence the heat load experienced by the cow are not commonly included in thermal indices used to measure heat stress; these include solar radiation, wind speed, and soil quality. Furthermore, the thermal comfort zone of cows has been altered by years of intense selection for increased milk yield, causing cows to become heat stressed at lower temperatures. Considering the abiotic and biotic factors affecting the cow’s heat load, it can be argued that dairy cows in tropical and subtropical climates are experiencing constant heat stress. In this review, the abiotic and biotic factors influencing the heat load experienced by dairy cows are reviewed, along with the available thermal indices that can be utilised at farm level.Submitted 27 August 2024; Accepted 27 November 2024; Published January 2025
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Significance of research to South African science
The research addresses the escalating impact of heat stress on dairy cows in a country experiencing rising temperatures at nearly twice the global rate. With most of South Africa’s dairy production relying on pasture-based systems, the review highlights the vulnerability of local herds to both environmental and physiological stressors. It evaluates the limitations of conventional thermal indices like THI and advocates for cow-specific and regionally relevant measures, while also exploring genetic adaptations such as the SLICK1 allele to improve heat tolerance. The study provides vital insights for climate-resilient livestock management, sustainable dairy production, and future research and policy aimed at safeguarding food security and rural livelihoods under climate change
Erratum to ‘PCV2: The unexpected threat – How fish infection can transform industries and society: A pilot study’
Get PDFThe article ‘PCV2: The unexpected threat – How fish infection can transform industries and society: A pilot study’ (SAJAS volume 54, issue 1, DOI: 10.4314/sajas.v54i1.11) was initially published with an incorrect author list.
The correct author list is as follows: D.F. Silva, F. Baldisseri, V.H. Silva, J.C.S. Borges, L.M. de Barros, Z.C.P. Caetano, C.I.S. Macedo, T.S. Oliviera, M.G. Souza, J.B. Gomes, A.P.S. da Silva, A.M.M.G. de Castr
Tannin extract dietary thresholds for preventing unacceptable suppression in intake, digestibility, and growth in sheep and cattle: A meta-analysis
Get PDFThis meta-analysis aimed to identify the optimal inclusion and threshold levels for black wattle, quebracho, and chestnut tannin extracts (TE) in sheep and cattle, in terms of their effects on dry matter intake (DMI), digestibility, weight gain, and nitrogen balance. Data were compiled from 44 scientific publications, representing 580 sheep and 742 cattle. The percentage change approach was used to quantify responses to TE inclusion. Mixed model analysis was performed to evaluate piecewise and linear regressions, with scientific publications treated as random effects, and TE level, TE source, animal species, supplementation period, dietary fibre level, dietary protein level, and animal age as fixed effects. The piecewise model provided the best fit for all responses. The optimal inclusion level was established at a 0% response, while the threshold was established at a 5% reduction in performance. With no differences between TE sources, the optimal inclusion level for DMI was 1.5 g TE/100 g dry matter (DM) and threshold was 3 g TE/100 g DM in both sheep and cattle. Sheep were slightly more able to digest crude protein than cattle (3.89 ± 1.91%) at the same TE inclusion level, but no other differences were observed between the two species. Black wattle TE reduced organic matter digestibility (−4.95 ± 1.82%), neutral detergent fibre digestibility (−8.62% ± 4.07), and acid detergent fibre digestibility (−16.83 ± 6.06) responses, relative to chestnut TE. Moreover, TE inclusion (particularly black wattle TE) raised faecal nitrogen while lowering urinary nitrogen. These differences between TE sources did not significantly influence the weight gain response, with an optimal inclusion level of 1.5 g TE/100 g DM, and a threshold of 2.3 g TE/100 g DM.
Submitted 13 June 2023; Accepted 10 February 2025; Published April 2025
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Significance of research to South African science
The article “Tannin extract dietary thresholds for feed intake, digestibility, growth, and meat quality of Damara and Meatmaster lambs” by Ahmed et al. (2025) holds important relevance for ruminant nutrition research and sustainable livestock production in South Africa. By investigating the effects of tannin-rich diets on indigenous sheep breeds, the study provides locally applicable insights into the optimal use of plant-based feed additives to improve animal performance without compromising meat quality. The findings support evidence-based recommendations for utilising tannin extracts as natural alternatives to synthetic growth promoters, aligning with South Africa’s goals of enhancing food safety, promoting environmentally responsible farming, and valorising underutilised forage resources in semi-arid regions. This research contributes directly to improving the productivity and sustainability of small ruminant systems across the country
Effects of different feeding regimes on growth performance, intake, digestibility, and ruminal metabolic and morphological characteristics in Awassi lambs
Get PDFThe aim of this research was to investigate the effects of different feeding regimes on the growth performance, nutrient intake, apparent digestibility, and ruminal metabolic and morphological characteristics of Awassi lambs. A total of 96 lambs (initial age: 10 ± 1 weeks; mean body weight: 23.62 ± 0.01 kg) were divided into four dietary groups in a completely randomised design (eight replicates/diet, three lambs/replicate). The four diets were as follows: control (CON: 50% barley grain, 50% long lucerne/alfalfa hay), diet 1 (D1: 100% complete pelleted feed), diet 2 (D2: 40% concentrate pellets, 60% long lucerne hay), and diet 3 (D3: 60% concentrate pellets, 40% roughage pellets). The lambs were fed the four diets for 84 days, and growth performance indicators were assessed twice (every 42 days) during this period. After 84 days, all target parameters, including morphometry, fermentation indicators, and bacterial activity in the lambs\u27 rumens, were assessed. The primary findings indicated that treatments D2 and D3 led to increased body weights, weight gains, and feed intakes. Lambs fed D2 had a higher dry matter intake and nutrient digestibility, along with increased papilla height, density, and total surface area. Specific fibre-degrading bacteria were more prevalent in D1, D2, and D3 than in the CON lambs. The higher total volatile fatty acid concentrations measured in the rumens of the D1, D2, and D3 lambs signified an improved fermentation profile. In conclusion, these results highlight the potential of complete diets and concentrate pellets with roughage sources to optimise performance, rumen health, and nutrient utilisation in lambs.
(Submitted 31 August 2025; Accepted 21 November 2025; Published 03 December 2025
Growth performance, faecal scores, and metabolic profiles of neonatal Holstein calves with extended transition milk feeding
Get PDFThe performance and health status of dairy calves may benefit from further transition milk feeding during the early postnatal period. However, transition milk obtained from cows during the first three to seven postpartum milkings is usually commingled with bulk tank milk by farmers. Therefore, this study aimed to evaluate the growth performance and health status of Holstein calves provided with extended transition milk feeding for the first three weeks of life. Twenty newborn singleton Holstein calves without any health problems or dystocia were blocked by birthweight, sex, and parity and assigned to two groups: control (fed normal milk after day 5, n = 10) and transition (fed transition milk up to day 21, n = 10). The calves were housed in individual hutches and weighed to determine their growth rate, and blood samples were collected on days 1, 7, 14, and 21. Residual calf starter pellets were weighed daily to calculate the feed conversion efficiency. The calves were monitored and their faecal scores were recorded daily. Feeding transition milk until 21 days of age improved the calves’ daily growth and calf starter pellet feed conversion efficiency. The calves’ faecal scores and blood parameters were not affected by transition milk feeding. No treatment × week interactions were observed in the calves’ growth performance, faecal scores, and blood parameters, except for the serum concentrations of aspartate aminotransferase and beta-hydroxybutyrate. In conclusion, feeding Holstein calves transition milk for the first three weeks of life is recommended to improve growth performance.
(Submitted 07 March 2023; Accepted 19 September 2025; Published 07 October 2025
Erratum: Assessing parallel testing to improve detection of bovine tuberculosis at a slaughterhouse in Lahore, Pakistan
Get PDFThe article ‘Assessing parallel testing to improve detection of bovine tuberculosis at a slaughterhouse in Lahore, Pakistan’ (SAJAS volume 54, issue 4, DOI: http://dx.doi.org/10.4314/sajas.v54i4.02) was initially published with an error in the second paragraph of page 497. This correction is important for the clarity and accuracy of the methodology described in the manuscript.
(Published 31 October 2025
The effects of dietary acid detergent fibre content on the performance of finishing lambs
Get PDFThis study investigated the effects of incremental increases in acid detergent fibre (ADF) content on the nutrient digestibility and performance of South African Mutton Merino wether lambs fed low-fibre finishing diets. Four dietary treatments were formulated with similar nutritional compositions, but with ADF concentrations of 46.8, 59.3, 63.8, and 79.9 g/kg dry matter. The digestibility study was conducted over seven days, while the production study was conducted over 67 days, after which the lambs were slaughtered. Significant differences between treatment means were declared at a 5% probability level. A high ADF concentration (79.9 g/kg) increased the finishing diet’s neutral detergent fibre and ADF digestibility. None of the other nutrients or dry matter digestibility values were affected by the change in ADF concentration. However, a low ADF concentration (46.8 g/kg) resulted in a significantly lower (more efficient) lamb feed conversion ratio, and less metabolisable energy was used for live weight gain. Carcass characteristics were unaffected by the dietary treatments. In conclusion, lamb performance was positively affected by a low ADF content in low-fibre finishing diets with a similar neutral detergent fibre content. More research is required to evaluate the effects of different ADF concentrations in high-fibre diets on nutrient digestibility and the performance of wether lambs.
Submitted 20 November 2024; Accepted 23 January 2025; Published March 2025
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Significance of research to South African science
The article contributes significantly to South African science by addressing feed efficiency in the country’s sheep production systems. Conducted at the University of the Free State, the study evaluates how varying levels of acid detergent fibre (ADF) in low-fibre finishing diets affect nutrient digestibility and lamb performance. Given the growing use of feedlot systems in South Africa\u27s mutton industry, this research provides locally relevant data on optimising dietary fibre to enhance growth efficiency without compromising carcass quality. Its findings support the use of lower ADF content for improved feed conversion, offering practical implications for more cost-effective and sustainable lamb finishing practices in the region
Heritability coefficients of growth traits of rainbow trout from a national selection programme
Get PDFIn order to create a selection programme aimed at improving the production characteristics of rainbow trout, broodstocks from eight fish farms in the Republic of Serbia were collected in 2010. The spawning of broodstocks, hatching of eggs, and rearing of offspring from different families of known parentage, until marking at five months of age, were carried out in individual tanks under strictly controlled conditions. After tagging, the fish were reared in a flow-through system on a commercial fish farm, where their growth was further monitored. The study of the phenotypic variability and heritability coefficients of the broodstock was carried out on a sample of 6565 individuals. The body weights and total lengths of the individuals were measured at five, 12, 24, and 36 months of age. Factors such as the year of spawning and sex proved to be highly statistically significant for the observed growth traits, while the heritability values of the analysed traits were moderate to high (0.22–0.68). The estimated heritability values provide an excellent basis for the continuation of the selective breeding programme, which will ultimately lead to the improvement of salmonid aquaculture and the profitability of rainbow trout production in the Republic of Serbia.
(Submitted 11 December 2024; Accepted 16 July 2025; Published 20 August 2025