Browsing by Author "Nyeleka, Sipokazi"

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    The potential of nutrifen® in broiler chicken production
    (Stellenbosch : Stellenbosch University, 2023-03) Nyeleka, Sipokazi; Pieterse, Elsje; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
    ENGLISH ABSTRACT: Plant-derived feed additives are currently the preferred alternatives in the search to replace antibiotic growth promoters (AGPs) in broiler chicken production. The emergence of plant-derived feed additives over the past decade is propelled by the European Union’s ban on AGPs (Regulation 1831/2003/EC) from all animal production. Owing to their secondary bioactive compounds that promote the survival of beneficial bacteria in the gastrointestinal system of broiler chickens, plant derived feed additives are being explored for use in the broiler meat industry. Although the broiler meat industry suffered tremendous losses since the outbreak of COVID-19, broiler meat still outcompetes the retail of beef, pork, and mutton. The broiler meat industry is still the fastest growing meat industry worldwide and is currently the biggest consumer of AGPs. Since their introduction to the broiler meat industry, AGPs enabled this industry to rear large volumes of flocks through minimising the effects of increased stocking density on farms. However, AGPs are increasingly receiving scrutiny as research findings associate their use in broiler meat production with the development and spread of multi-drug resistant pathogenic bacteria. These bacteria are considered a serious threat to human health and the environment. Consequently, international food and health bodies such as the Food and Agriculture Organisation (FAO), the World Health Organisation (WHO) together with consumers are calling for the adoption of feed additives that will not pollute the environment and will not compromise the health of the animal. Feed additives derived from plants meet these requirements. Although research on plant-derived feed additives is ongoing, it is mainly focused on production parameters such as weight gain and portion sizes where broilers are reared in ideal or optimum environmental conditions. For this reason, there is little emphasis on the functional use of plant-derived feed additives when broilers are challenged with common environmental stressors such as stocking density. Consequently, little is known about the efficacy of some plant-derived feed additives to minimize the production effect of stressful environmental conditions. Nutrifen® is a feed additive developed from the seeds of fenugreek (Trigonella foenum-graecum L.). The present study investigated the potential of Nutrifen® to minimise the production effects when broiler chickens are challenged through stocking density. The first objective of the study characterized Nutrifen® in terms of chemical composition, antioxidant potential, and overall presence of phenolic compounds. Nutrifen® was shown to be characterized by a high crude fibre and crude protein content. The presence of polyphenols in Nutrifen® was confirmed by the total phenolics (TPC) test, while the antioxidant potential was confirmed by the ferric reducing ability of plasma (FRAP) and the 2,2-diphenyl- 1-picrylhydrazylradical (DPPH) DPPH results. The second objective of this study involved determining the effect of different levels of Nutrifen® in broiler diets on feed intake (FI) and visceral organ development in a trial that was repeated six times. Nutrifen® was included at five inclusion levels (i.e. 0g/ton; 0.44g/ton; 0.88g/ton; 0.132g/ton; and 0.176g/ton) in broiler diets, which were fed to 300 day-old chicks. It was concluded that under well ventilated, clean housing conditions, the birds did not reject any of the treatment diets. In the absence of a significant treatment effect, the lowest level of Nutrifen® inclusion (i.e. 0.44g/ton) which was assumed to be the most cost-efficient to include in broiler diets, was used to investigate the third and fourth objectives. In objective three, stocking density was used as a stressor, where 204 day-old Cobb500TM unsexed broiler chicks were used. The chicks were reared to final stocking densities of 20kg/m2 (low stocking density; 10 birds per pen) and 28kg/m2 (high stocking density; 14 birds per pen). The experiment was a 2X2 factorial completely randomized design, with each diet- stocking density combination replicated six times. The results of this study show that that 0.44g/ton Nutrifen® did not improve the live weight (LW), body weight gain (BWG), and average daily gain (ADG) of broilers kept at a high stocking density. The fourth objective of the study determined the influence of Nutrifen® (i.e. included at 0.44g/ton) on organ health, carcass, and shelf-life display quality of broilers reared at the abovementioned stocking densities. The same birds used in objective three were used for this study. From the results obtained, it is apparent that supplementing the diets of stressed broilers with 0.44g/ton Nutrifen® decreased carcass and portion weights. In addition, the pH of the breast muscle was significantly lower for the stressed broilers on the day of slaughter and water retention of the breast muscle was poor for these broilers. However, the weight of the Bursa of Fabricius of the stressed broilers was significantly higher compared, when compared to the birds maintained at the lower stocking density. In conclusion, Nutrifen® can be supplemented as a feed additive in broiler diets at 0.44g/ton without compromising growth or resulting in intestinal damage in broilers, maintained under optimum environmental conditions and a low stocking density.