Effects of dietary level of selenium and grain on digestive metabolism in lambs

The objective was to evaluate the effect of different levels of selenium with two levels of grain corn in the diets on ruminal, postruminal, and total tract digestion of nutrients, ruminal fermentation characteristics, and selenium balance in lambs. A split-plot design was used in four periods with repeated Latin square using eight Suffolk × Dorset male lambs with four levels of selenium (sodium selenite, Na2SeO3), without adding selenium, 0.3, 0.6, and 0.9 mg of selenium/kg dry matter (DM) with 70 and 50% of corn grain in the diet. The four selenium levels affected organic matter as follows: starch, neutral detergent fibre, nitrogen and selenium excretion; selenium ruminal digestion; organic matter, neutral detergent fibre, nitrogen and selenium postruminal digestion; and organic matter, neutral detergent fibre, nitrogen and selenium total tract digestion (P < 0.05). Starch and organic matter flow decreased with 0.6 and 0.9 mg of selenium with the 70% grain diet (P < 0.05). Selenium flow increased linearly with selenium levels (P < 0.01) with both levels of grain. Selenium supplementation increased linearly selenium concentration in ruminal fluid (P < 0.01), but did not affect other ruminal characteristics. Also, selenium absorption and retention was increased by selenium concentrations (P < 0.01). The apparent absorption of selenium increased (31%, P < 0.01) with the 70% grain diet. In conclusion, the high content of nonstructural carbohydrates improved the availability of selenium and 0.9 mg of selenium/kg DM improved the absorption and availability of selenium.