Daily and alternate-day supplementation of urea or biuret to ruminants consuming low-quality forage. II. Effects on site of digestion and microbial efficiency in steers

Five steers (491 +/- 21 kg BW) were used in an incomplete 5 x 4 Latin square with four 24-d periods to determine the influence of supplemental nonprotein N (NPN) source and supplementation frequency (SF) on nutrient intake and site of digestion in steers consuming low-quality grass straw (4% CP). Tr...

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Bibliographic Details
Published in:Journal of animal science 2004-05, Vol.82 (5), p.1518-1527
Main Authors: Currier, T.A, Bohnert, D.W, Falck, S.J, Schauer, C.S, Bartle, S.J
Format: Article
Language:English
Subjects:
Animal Feed - standards
Animal productions
Animals
Bacteria - metabolism
Biological and medical sciences
biuret
Biuret - administration & dosage
Cattle - metabolism
Dietary Supplements
Digestion
Drug Administration Schedule - veterinary
feed supplements
feeding frequency
Fundamental and applied biological sciences. Psychology
Male
nitrogen
Nitrogen - metabolism
nonprotein nitrogen
nutrient intake
Nutritional Requirements
protein intake
protein supplements
Random Allocation
Rumen - metabolism
Rumen - microbiology
rumen bacteria
rumen fermentation
steers
straw
Terrestrial animal productions
urea
Urea - administration & dosage
Vertebrates
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Summary:Five steers (491 +/- 21 kg BW) were used in an incomplete 5 x 4 Latin square with four 24-d periods to determine the influence of supplemental nonprotein N (NPN) source and supplementation frequency (SF) on nutrient intake and site of digestion in steers consuming low-quality grass straw (4% CP). Treatments (TRT) included an unsupplemented control and a urea- or biuret-containing supplement placed directly into the rumen daily (D) or every other day (2D) at 0700. The NPN treatments were formulated to provide 90% of the estimated degradable intake protein requirement. Daily TRT were supplemented CP at 0.04% of BW/d, whereas the 2D TRT were supplemented at 0.08% of BW every other day. Therefore, all supplemented TRT received the same quantity of supplemental CP over a 2-d period. Forage OM intake was not affected (P > 0.05) by NPN supplementation, NPN source, or SF; however, total OM and N intake were increased (P < 0.01) with CP supplementation. Duodenal flow of N was greater (P = 0.04) with CP supplementation compared with the control. In addition, duodenal bacterial N flow was increased with CP supplementation (P = 0.04) and for biuret compared with urea (P < 0.01). Bacterial efficiency (g bacterial N/kg OM truly digested in the rumen) was greater (P = 0.05) for biuret than for urea. Apparent total-tract N digestibility was increased with NPN supplementation (P < 0.01) but not affected by NPN source or SF. These results suggest that urea or biuret can be used effectively as a supplemental N source by steers consuming low-quality forage.
ISSN:0021-8812
1525-3163
DOI:10.2527/2004.8251518x