Effects of Soybean Based Supplements on Lamb Growth Performance and Muscle Fatty Acid Composition of Pasture Reared Lambs Finished on a Hgih Forage Diet

Abstract

The effects of fat (F), protein (PR), and fat enriched protein (FP) soybean-based supplements on growth performance and muscle fatty acid profile of lambs were investigated. Thirty-three lambs (19.71 ± 1.74 kg) were randomly assigned to receive one of three supplements for the final 29 days of an 81-day stay on mixed pastures and then for an additional 39 days finishing period on drylots. During this latter period, lambs were fed orchard grass and alfalfa hay (1:1) along with the supplement. At the end of the study overall ADG, HCW and the fatty acid profile of lamb muscle were determined for 3 lambs in each treatment group. The quantity and quality of forage available to lambs while on pasture and accessibility to that forage ere similar across treatments. The average quantity of supplement and hay consumed daily was above 80% of what was offered and was similar across treatments. Daily gains of lambs after 29 days supplementation while on pasture differed (F=0.30, PR=0.22, FP=0.27 ± 0.02 kg/d, P=0.05). During the first 2 weeks in the drylot, ADG differed amongst treatments (F=-0.05, PR=0.23, FP=0.11 ± 0.05 kg/d, P 0.05), but dressing percentage tended to be higher in PR than in F and FP wethers (46.62, 44.27 and 43.85 ± 0.76%, P=0.08). The SFA: UFA of lamb muscle was lower in the F and FP than in PR treatments (0.98 vs. 1.38 and 1.22 ± 0.07, P=0.02). Feeding of soybean based non-commercial fat supplements achieved targeted increases in average daily gains in high forage fed lambs and influenced fatty acid profile of lamb muscle.