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.
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.
Krehbiel
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Roman L. Hruska U.S. Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933, USA.
Ferrell
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Freetly
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D000588:Amines / Q000097:blood; D000641:Ammonia / Q000097:blood; D000821:Animal Feed / Q000592:standards*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D019587:Dietary Supplements; D004435:Eating / Q000502:physiology*; D005260:Female; D007773:Lactates / Q000097:blood; D008099:Liver / Q000378:metabolism*; D009584:Nitrogen / Q000097:blood; D010100:Oxygen / Q000097:blood; D006109:Poaceae; D011168:Portal System / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism*; D013025:Glycine max; D014508:Urea / Q000097:blood; D014781:Viscera / Q000378:metabolism
D000588:Amines; D001786:Blood Glucose; D007773:Lactates; D000641:Ammonia; D014508:Urea; D009584:Nitrogen; D010100:Oxygen