The effects of intraruminal infusion of sodium selenite on the in-sacco degradability of Centrosema pubescens and Pennisetum purpereum in west African dwarf sheep

Abstract

This trial describes the effect of intraruminal infusion of sodium selenite on the in-sacco rumen degradability of a legume, Centrosema pubescens and a grass, Pennisetum purpereum in West African dwarf (WAD) sheep. A total of sixteen WAD sheep of an average body weight, 16.19 ± 2.63 kg were used for this study. A 4 x 4 Latin square design of four sheep and four sodium selenite treatments (doses) for each forage in both the experimental (group A) and control group (group B) was adopted. Using the nylon bag technique, percentage disappearance of dry matter (DM), organic matter (OM) and crude protein (CP) fractions as well as their degradation constants were determined at time intervals of 8, 12, 24, and 48 hours following daily intraruminal infusions of 50, 100, 150 and 200ìg of sodium selenite per sheep within each Latin square. The results of the study showed that addition of sodium selenite improved rumen degradability of feed fractions when compared with the control. All the concentrations of sodium selenite significantly (p < 0.05) increased the percentage disappearance of all the feed fractions, in a dose dependent manner, compared to the control particularly up to a maximum dose of 150ìg beyond which a decline in degradability was observed for all the feed fractions. The results of the study also showed significant correlation (r2 = 0.56) between period of incubation and percentage disappearance of feed fractions for both forages with relatively more time required for disappearance of DM, OM and CP in the grass (Pennisetum purpereum) than the legume (Centrosema pubescencs). It was therefore concluded that sodium selenite at a maximum concentration of 150ìg, when infused into the rumen, is safe and improves rumen degradability of virtually all forage fractions. Thus sodium selenite could be valuable as a feed additive in ruminant diets particularly to improve the rumen degradability of probably more fibrous, low protein feedstuffs. This calls for a focus on sodium selenite as a possible manipulator of rumen function for efficient utilization of poorly degraded feedstuffs.