Comparison of Acacia mearnsii and Medicago sativa as substitutes for Glycine max in cattle finisher diets: Effects on beef production and quality

Abstract

Beef production in the smallholder sector of South Africa is constrained by low feed quantity and quality, particularly protein during the dry season. The objective of the study was to evaluate the effect of replacing Glycine max in a complete finisher beef cattle diet with either Acacia mearnsii leaf meal or Medicago sativa hay on growth performance, carcass traits and meat quality of steers. Thirty-six, 12-months old non-descript crossbred steers (157.9 ± 31.37 kg body weight) were randomly allocated to three dietary treatments (12 animals/treatment), with A. mearnsii and M. sativa replacing G. max (control diet) at 500 g/kg dry matter (DM) of diet. Steers fed the A. mearnsii diet had lower (P ≤ 0.05) DM intake, average daily gain, feed efficiency and carcass weights than those fed G. max and M. sativa diets with no difference found between G. max and M. sativa treatments (P > 0.05). Diet had no influence on any of the measured meat physicochemical traits (P > 0.05). Overall, steers fed the M. sativa and G. max diets had similar growth performance and meat yield, but higher (P ≤ 0.05) than that of steers fed the A. mearnsii diet. Current results suggest that M. sativa is a better alternative protein source to G. max for smallholder beef cattle compared to A. mearnsii.