INFLUENCE OF ENERGY SUPPLEMENTATION ON NITROGEN KINETICS IN THE RUMENAND UREA METABOLISM

Firstly, this paper reviewed the effects of supplementary energy suppl y on nitrogen utilization, nitrogen kinetics in the rumen and urea met abolism in ruminants. Improving the utilization of dietary nitrogen by increasing microbial yield is possible through energy supplementation , but the type of supplement and level of intake required differ betwe en diets. Secondly, the effects of sucrose supplementation on rumen fe rmentation and nitrogen kinetics were examined in sheep fed freshly cu t lucerne, lucerne chaff and hay cubes. In this experiment, the method of isotope dilution of C-14-urea, N-15-urea, H-3-glucose and N-15-amm onium salt was used for the estimation of parameters of metabolism. Su pplementation with sucrose decreased the urinary N excretion, resultin g in an increase in N retention. Supplementation with sucrose resulted in a lower rumen ammonia and plasma urea concentration. The fermentat ion of sucrose in the rumen resulted in a decrease in rumen pH and in the ratio of acetate to propionate. Sucrose supplementation increased the proportion of urea transferred to the rumen, the non-ammonia N (NA N) concentration in the rumen and the NAN flow from the rumen to the l ower digestive tract. Urinary allantoin excretion rate increased with sucrose supplementation. The plasma glucose concentration did not chan ge but the plasma insulin concentration increased with sucrose supplem entation. The influence of an energy-rich supplement on the utilizatio n of N and N kinetics in the rumen and whole body of domestic ruminant s is discussed.