Effects of dietary replacement of broiler litter withMelia azedarachfoliage on productive performance, fatty acid composition and health-related fatty acid indices in beef fats from Nguni x Brahman steers fed sugarcane tops based diets

Abstract

AbstractThe study investigated the nutritional value ofM. azedarachLinn. (umsilinga;Meliaceaefamily) leaf meal (MALM) as an alternative protein source for beef cattle. In a completely randomised design (CRD), 18 Nguni x Brahman 18–20 months old steers were randomly offered 3 iso-energetic and iso-nitrogenous dietary treatments with, respectively, 0% (Control), 15% and 30% MALM replacing broiler litter, each with 6 replicate animals, for 90 days. Feed intake (FI), water intake (WI), slaughter weight, body weight gain (BWG), feed conversion efficiency (FCE) and kidney fat depot fatty acid (FA) composition as well as health-related FA totals, ratios and other indices were measured. Results showed MALM contained rather high CP (290.0 g/kg DM), CF (170 g/kg DM), EE (78.1 g/kg DM) and ash (77.5 g/kg DM) contents. Also, dietary supplementation with MALM increased BWG and FCE (P < 0.01) but had no effect on FI, WI and slaughter weight of steers (P > 0.05). Also, it increased kidney fat margaric acid (P < 0.05) whilst it decreased arachidic acid (P < 0.01) content. There was no effect of diet on the content of all other saturated fatty acids (SFAs) (P > 0.05) in kidney fat. Further, dietary MALM supplementation increased kidney fat α-linolenic (P < 0.001) and conjugated linoleic acid (CLA) (P = 0.01) but had no effect on the content of all other unsaturated fatty acid (UFA) components (P > 0.05). Furthermore, it increased kidney fat total polyunsaturated fatty acids (PUFAs) (P < 0.01), total omega-3 (n-3) PUFAs (P < 0.001) and the CLA/vaccenic acid index but decreased the omega-6/omega-3 (n-6 PUFA/n-3 PUFA) ratio (P = 0.001). Otherwise, dietary MALM supplementation had no effect on all other FA totals, ratios and health-related indices (P > 0.05). In conclusion, dietary MALM supplementation improved productive performance of beef steers and enhanced their desirable meat fat FA profiles.ImplicationsBroiler litter is widely used as an alternative cheap protein and mineral rich feedstuffs for supplementing poor quality forage based diets for ruminants in Southern Africa and elsewhere. However, its use is limited by the presence of human pathogens, pesticides, drug residues and heavy metals, which pose health hazards to livestock and human consumers. Our study demonstrated MALM as a better and safer alternative source of protein, the use of which in beef cattle diets would improve animal productivity and the desirable FA profile of meat which would potentially enhance the health status of consumers. By improving beef productivity, dietary MALM supplementation thus promises to enhance food and nutrition security and to contribute to poverty alleviation in Eswatini, Africa and beyond.