Effects of feed intake and dietary urea concentration on ruminal dilution rate and efficiency of bacteria growth in steers
Four multiple-fistulated steers (340 kg) were fed a diet containing 50% ground grass hay, 20% dry distillers grains, and 30% concentrate at two intakes (7.2 or 4.8 kg DM/d). Urea (.4 or 1.2% of the diet) was infused continuously into the steers' rumens. The experimental design was a 4 x 4 Latin square with a 2 x 2 factorial arrangement of treatments. Infusing urea at .4 or 1.2% of the diet resulted in ruminal NH/sub 3/ N concentration of 4.97 and 9.10 mg/dl, respectively. Feeding steers at high rather than low intake decreased ruminal and total tract digestibilities of organic matter, NDF, and ADF but did not increase ruminal escape of N. However, apparent N escape from the rumen calculated using purines, but not /sup 15/N, as a bacterial marker was higher when 1.2 vs. .4% urea was infused. Feeding at high rather than at low intake increased the total pool of viable bacteria per gram organic matter fermented in the rumen. Although ruminal fluid outflows and particulate dilution rates were greater when steers were fed at high than low intakes, efficiencies of bacterial protein synthesis were unaffected by intake. The possibility of increased N recycling within the rumen with feeding at the higher intake is discussed.
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- OSTI ID:
- 5280746
- Journal Information:
- J. Dairy Sci.; (United States), Vol. 70:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
60 APPLIED LIFE SCIENCES
BACTERIA
GROWTH
CATTLE
METABOLISM
PROTEINS
BIOSYNTHESIS
DIET
INTAKE
NITROGEN 15
TRACER TECHNIQUES
ANIMALS
DOMESTIC ANIMALS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAMMALS
MICROORGANISMS
NITROGEN ISOTOPES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
RUMINANTS
STABLE ISOTOPES
SYNTHESIS
VERTEBRATES
550501* - Metabolism- Tracer Techniques
553005 - Agriculture & Food Technology- Animal Husbandry- (1987-)