South African Journal of Animal Science

Gut dysbiosis: Nutritional causes and risk prevention in poultry, with reference to other animals

A. Salahi — 2025-03-08

The 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.

The effect of ecotype and year on the production and reproductive performance of Nguni cows in the Limpopo Province of South Africa

M. Mulaudzi — 2025-03-08

This study investigated the effects of Nguni cattle ecotype and year on the production and reproductive performance of cows in the Limpopo Province of South Africa. Production data for 471 calvings (142 Venda, 65 Shangaan, and 264 Pedi ecotype Nguni cows) at Mara Research Station were analysed to determine the differences between years and ecotypes in birthweight, weaning weight, days-toreconception, inter-calving period, weight of cow at breeding and at weaning, and weaning efficiency. The effects of ecotype and year on the production and reproduction parameters were analysed using the SAS® mixed models procedure. Cows of the Shangaan ecotype were the smallest in size, while the Venda ecotype was both heavy and short, and gave birth to calves with lower birthweights and higher weaning weights. Ecotype did not affect the inter-calving period and days-to-reconception, but influenced weaning efficiency and weight-related reproduction traits. Year influenced the birth and weaning weights, with years with high precipitation also having high production efficiencies. The smaller-framed Shangaan ecotype had a better weaning efficiency, days-to-reconception, and inter-calving period than the Pedi and Venda ecotypes in the year with the lowest precipitation (2011). No year effects were observed for days-to-reconception, but the inter-calving period, weaning efficiency, and weight-related reproductive traits were affected by year. Ecotype and year thus both influenced the production and reproduction traits of Nguni cattle.

Breeding practices and trait preferences of sheep farmers from two villages in Lepelle-Nkumpi municipality, Limpopo Province, South Africa

A.M. Phaladi — 2025-03-08

Despite the large genetic diversity within South Africa’s sheep population, average productivity on smallholdings remains low. This study therefore aimed to identify the breeding practices and trait preferences of sheep farmers in the Makurung and Lenting villages, Limpopo Province, for use in the development of a community-based breeding programme. Data were collected from 70 purposively sampled farmers in the two villages using a questionnaire survey method. Descriptive analysis, significance testing, and index ranks using SPSS software were employed to describe and analyse the collected data. Most (48.8%) of the sheep farmers in both villages kept sheep for savings and investment, and meat production purposes. The overwhelming majority (90.0%) of sheep farmers in both villages practised uncontrolled mating, but a significant difference in breeding practices was observed between the villages. Knowledge of castration and culling practices did not significantly differ between the villages. The sheep farmers’ preferred traits for breeding rams were mating ability (0.3), body size (0.3), and growth rate (0.2), while for breeding ewes they were twinning ability (0.3), mothering ability (0.2), and lambing interval (0.2). We conclude that farmers should focus more on ewe reproductive anatomy traits (such as udder size and shape, and teat size and placement), and ram reproductive anatomy traits (such as scrotal size and circumference, and testicular size and weight), as these can have an impact on long-term flock productivity. These findings could guide interventions such as the establishment of sustainable community-based breeding schemes to improve sheep production in the study area.

The effect of a phytogenic-based feed additive on concurrent Lawsonia intracellularis and Brachyspira hyodysenteriae infections in pigs

C.F. Wu — 2025-03-08

This study investigated the efficacy of a commercial phytogenic-based premixed feed additive (PFA) in treating combined Lawsonia intracellularis and Brachyspira hyodysenteriae infections in finishing pigs, with tiamulin/lincomycin treatment as the control. Pigs aged 20 weeks were allocated to PFA treatment (11 pens, 45 pigs per pen) and control (7 pens, 43 pigs per pen) groups for a sevenweek experimental period. Floor faecal samples and rectal swabs were collected weekly, and the percentage of pigs per pen with diarrhoea was recorded weekly. The bacterial contents of the samples were determined using real-time polymerase chain reaction, and at the end of the experiment, histological changes in ileal samples were examined. There was an intermittent decrease in L. intracellularis in the control group (from 4.85 to 0.82 DNA log₁₀ copies/µl) and a continuous reduction in L. intracellularis in the PFA group (from 5.69 to 0.64 DNA log₁₀ copies/µl) over a six-week period. B. hyodysenteriae was not detected in rectal swabs from the control group at week six, and an intermittent decrease in B. hyodysenteriae, from 3.04 to 0.26 DNA log₁₀ copies/µl, was observed in the PFA group. Bacterial DNA in the floor faecal samples declined during the seven-week experimental period, as found for the rectal swabs. There were no cases of diarrhoea from week two onwards in the control group and week three onwards in the PFA group. The results of this study indicate that a PFA rich in essential oils has a therapeutic effect comparable to that of tiamulin/lincomycin in pigs with proliferative enteropathy and swine dysentery.