Effect of dietary protein level on nitrogen utilization and ruminal influx of endogenous urea nitrogen in growing animals
Three experiments were conducted to evaluate the impact of ruminal influx of blood urea nitrogen (BUN) on intestinal protein supply and nitrogen (N) metabolism in growing animals at both excess and growth-limiting protein intake. In Experiment 1, wether lambs were given diets, either high or low in protein, containing 25% cottonseed hulls and 75% corn-soybean meal hourly in 24 equal portions. Single injections of /sup 14/C- and /sup 15/N-urea, and /sup 15/N-ammonium sulfate (AS) were made into the BUN and ruminal ammonia N (RAN) pools, respectively, to measure rate of flux through, and transfer of N between these and the bacterial N pool. In Experiment 2, beef calves were given HP and LP diets containing 30% cottonseed hulls and 70% corn-soybean meal every 4 h in 6 equal portions. Single injections of /sup 15/N-urea and /sup 15/N-AS were made into the BUN and RAN pools, respectively, to measure rate of flux through, and transfer of N between these and the bacterial N pool. Abomasal N flow was 24% greater than intake in LP and 29% less than intake in HP. An inverse relationship may exist between level of N intake and rate of influx of BUN into the rumen. In Experiment 3 ruminal fluid samples were obtained. With HP, BUN-derived /sup 15/N-ammonia appeared to rapidly equilibrate with RAN in the primary digesta mass. In contrast, with LP, there appeared to be an enrichment gradient for both RAN and bacterial N, declining from the rumen wall toward the center of the digesta mass, suggesting that bacteria at or near the rumen wall may preferentially utilized some BUN-derived ammonia N entering through the rumen wall.
- Research Organization:
- Kentucky Univ., Lexington (USA)
- OSTI ID:
- 5989977
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NITROGEN COMPOUNDS
METABOLISM
PROTEINS
BIOLOGICAL EFFECTS
RUMINANTS
ANIMAL GROWTH
CARBON 14 COMPOUNDS
DIET
NITROGEN 15
TRACER TECHNIQUES
UREA
AMIDES
ANIMALS
CARBONIC ACID DERIVATIVES
GROWTH
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
MAMMALS
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
STABLE ISOTOPES
VERTEBRATES
550501* - Metabolism- Tracer Techniques