THE INFLUENCE OF NIACIN SUPPLEMENTATION ON GROWING RUMINANTS AND IN VIVO AND IN VITRO RUMEN PARAMETERS
Abstract
A series of experiments were conducted to investigate the effect of niacin supplementation on growing beef cattle and lambs, in vitro fermentations and in vivo rumen parameters. Steers and lambs were fed typical feedlot diets supplemented with either soybean meal or urea. Those receiving soybean meal and growing rapidly responded to niacin supplementation (100 parts per million, dry matter) by improved (p < .05) growth rate and efficiency of feed conversion. The feeding of monensin and niacin to growing steers appeared to act synergically. During metabolism trials, improved nitrogen utilization, as represented by increased nitrogen retention, was observed for lambs receiving the soybean meal and niacin-supplemented diet. For in vitro fermentation using a semicontinuous technique, niacin supplementation improved (p < .05) microbial protein production regardless whether nitrogen was supplied as either a crystalline amino acid mixture, similar in composition to soybean meal, or as NH(,4)Cl. This indicates at the levels fed, the rumen appears to be the active site for niacin supplementation and its influence on nitrogen utilization. For lambs adjusting to a urea-containing diet, niacin supplementation tended to improve nitrogen utilization during this adjustment period. Rumen liquid volume and liquid turnover rate during this adjustment period were reduced initially and then increased with time, when introduced to a urea-containing diet. It appears niacin supplementation at 100 ppm to growing ruminants is active in the rumen by increasing microbial protein synthesis and improving nitrogen utilization in the animal.
Degree
Ph.D.
Subject Area
Livestock
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