The effects of feeding regimen and dietary sucrose supplementation on natural abundance of 15N in some components of ruminal fluid and plasma of sheep.

An experiment was conducted to investigate the effects of changes in ruminal conditions arising from feeding and sucrose supplementation to the diet on the natural abundance of 15N ( 6 15N value) of some biological components and of feces and urine in sheep. Four wethers fitted with ruminal fistulas were fed on alfalfa hay cubes with or without sucrose either 2 or 12 times daily. With twice-daily feeding, the 6 15N values of ruminal ammonia and plasma urea decreased after feeding, whereas only small changes were observed throughout the sampling period with 12 times daily feeding. With 12 times daily feeding with and without sucrose, the 6 15N values of ruminal ammonia were higher ( P < .05) than those of the diet and plasma urea. The 6 15N values of ruminal bacteria were lower ( P < .05) than