title: Net absorption from portal-drained viscera of nitrogenous compounds by beef heifers fed on diets differing in protein solubility or degradability in the rumen.
abstract: The objective of the present study was to evaluate effects of in vitro rumen solubility or degradability of dietary protein on net absorption of nitrogenous compounds from portal-drained viscera of beef heifers. Four protein sources, casein, soya-bean meal, maize-gluten meal and blood meal provided about two-thirds of total dietary nitrogen in semi-purified diets given to four beef heifers in a 4 X 4 Latin square design. Although in vitro degradability of dietary N ranged from 842 (casein) to 310 (blood meal) g/kg total dietary N, net absorption of ammonia-N or alpha-amino-N was not significantly different (P greater than 0.10) among diets. However, net absorption of NH3-N tended to decrease and net absorption of alpha-amino-N tended to increase as intake of in vitro undegradable N increased. Net transfer of urea-N from plasma to portal-drained viscera was greater (P less than 0.10) when heifers were fed on soya-bean meal than when fed on maize-gluten meal or blood meal. The findings show with all diets that the non-protein-nitrogenous compounds, NH3 and urea, played a substantial role in absorption and transfer of N. Overall, net absorption of NH3-N was 61% of net absorption of alpha-amino-N, and transfer of urea-N from plasma to portal-drained viscera was 80% of net absorption of alpha-amino-N.
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D005260:Female; D007408:Intestinal Absorption; D009584:Nitrogen / Q000378:metabolism*; D011168:Portal System; D012417:Rumen / Q000378:metabolism; D012995:Solubility; D014781:Viscera / Q000098:blood supply / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D009584:Nitrogen