Interaction of dietary selenium and magnesium level on digestive function in lambs fed high-concentrate diets

A metabolism trial involving 4 Suffolk lambs (30.8 kg) cannulated in the rumen and proximal duodenum were conducted to evaluate the interaction of dietary Sel 0.10 vs 0.30 mu g) and Mg level (0.18 vs 0.32%) on digestive function. Passage of feed N to the small intestine was greater (P<0.1) with 0.32% dietary Mg, and there was an interaction (P<0.05) between Mg and Se supplementation on feed N flow to duodenum and rumen digestion. There was an interaction between dietary Mg and Se level on passage of Mg and Se to the small intestine (P<0.05), ruminal solubility Mg concentration, molar proportion of acetate and acetate: propionate molar ratios. 0.3 mu g Se increased (P<0.05) molar concentrations of butyrate. It is concluded that requirement levels of Se and Mg for feedlot lambs is substantially higher than that recommended by NRC.