Effects of Rumen-Protected Choline on Growth Performance, Carcass Characteristics and Blood Lipid Metabolites of Feedlot Lambs

SIMPLE SUMMARY: Choline is important for animal health, due to its involvement in the synthesis of vital molecules in the body. Several feed materials used in animal nutrition contain choline, but this naturally occurring choline is rapidly degraded in the rumen, therefore, it should be offered as rumen-protected choline (RPC) in ruminant animal species. Here we describe the results of a study that we performed with the aim of evaluating the effect of RPC on growth, carcass, and some blood metabolites in feedlot lambs. RPC supplementation did not significantly affect dry-matter intake, weight gain, gain:feed ratio, or carcass weights. Interestingly, RPC supplementation was associated with lower blood triglycerides and increased backfat thickness and yield grade, thus suggesting an effect of RPC on lipid metabolism. RPC supplementation was also associated with a reduced height to the shoulder and longissimus muscle area, suggesting an inhibitory effect of RPC on growth. The results of this study do not support the use of RPC supplementation to improve animal performance or carcass characteristics in feedlot lambs. ABSTRACT: Choline is an essential nutrient for animals, but dietary choline is degraded in the rumen, and thus, should be offered as rumen-protected choline (RPC) in ruminants. In this article, we investigate the effect of RPC supplementation in feedlot lambs. Forty intact male Saint Croix lambs (average: 20.3 kg, 3–4 months of age) on a high grain-low roughage base feed were randomly assigned to four treatments (0, 0.1, 0.2, and 0.3% RPC on dry-matter basis; n = 10 per group). RPC was offered for 90 days after 15 days of adaptation. RPC supplementation was not associated with significant differences in dry matter intake, weight gain, gain:feed ratio, carcass weights, and the dressing percentages. There was a linear decrease in height to the shoulder (p = 0.013) and longissimus muscle area (p = 0.051) with higher RPC levels, and a higher backfat thickness and yield grade with 0.3% RPC compared to 0.1% RPC (p < 0.05). Blood triglycerides concentrations were higher in control (0% RPC) compared to 0.3% RPC (p = 0.008). The lack of significant effects on growth performance and the results on backfat thickness and yield grade, may indicate undesirable effects associated with RPC supplementation. More research is needed to establish the needs and specific quantities of RPC supplementation in feedlot lambs.