Effects of frequency of supplementation on dry matter intake and net portal and hepatic flux of nutrients in mature ewes that consume low-quality forage

J Anim Sci. 1998 Sep;76(9):2464-73. doi: 10.2527/1998.7692464x.

Abstract

Our objective was to determine the effects of frequency of soybean meal (SBM) supplementation on forage intake and net portal-drained viscera (PDV) and hepatic flux of nutrients in ewes that consume low-quality forage. Six Polled Dorset ewes (BW+/-SD = 82+/-9 kg) fitted with hepatic venous, hepatic portal, abdominal aortic, and mesenteric venous catheters were used in a replicated 3 x 3 Latin square design. Ewes consumed bromegrass hay (7.5% CP; DM basis). Treatments were no supplement (control), SBM fed once every 24 h, or SBM fed once every 72 h. In the SBM treatments, SBM was fed to provide 80 g/d of CP. Blood flow and net flux measurements were made on the 3rd d of each period so that ewes supplemented every 72 h were sampled the day of, the day after, and 2 d after supplementation. Arterial concentrations of alpha-amino N (AAN) and ammonia N were lower (P < .01) when SBM was fed, whereas arterial concentrations of urea N and oxygen were higher (P < .01). Feeding SBM increased net PDV release of AAN and ammonia N, net PDV removal of urea N, and oxygen consumption. A SBM x sampling day interaction (P < .05) occurred and resulted in greater net PDV absorption of AAN and ammonia N on the day after SBM supplementation when ewes were fed SBM on a 72-h interval. Net hepatic removal of AAN, ammonia N, and oxygen, and net hepatic release of urea N were greater (P < .01) with feeding SBM. The results indicate that the interval of SBM supplementation may affect the pattern of absorption without affecting the net absorption of nutrients.

MeSH terms

  • Amines / blood
  • Ammonia / blood
  • Animal Feed / standards*
  • Animals
  • Blood Glucose / metabolism
  • Dietary Supplements
  • Eating / physiology*
  • Female
  • Glycine max
  • Lactates / blood
  • Liver / metabolism*
  • Nitrogen / blood
  • Oxygen / blood
  • Poaceae
  • Portal System / metabolism*
  • Sheep / metabolism*
  • Urea / blood
  • Viscera / metabolism

Substances

  • Amines
  • Blood Glucose
  • Lactates
  • Ammonia
  • Urea
  • Nitrogen
  • Oxygen