Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 1/14/2000
Publication Date: 3/15/2000
Citation: McDonagh, M.B., Freetly, H.C., Ferrell, C.L. 2000. Effects of feeding corn vs. casein in concentrated rations on flux of nitrogenous compounds across the PDV [abstract]. Journal of Animal Science. 78(Suppl. 2):95.
Technical Abstract: This experiment compared the flux of nitrogenous compounds across the portal-drained viscera (PDV) in seven growing lambs (25.9 +/- 3.3 kg) fed concentrated rations in a incomplete latin square design. The rations were one level of unbalanced protein intake (corn, corn gluten and urea with alfalfa) or three different levels of balanced protein intake (casein with cornstarch, solka floc and molasses). Lambs were estimated to require 205 g/d protein for rapid growth. Rations were fed at equal amounts and equal energy content in 3-wk blocks, after which PDV measurements were taken. Random effects were actual crude protein intake by ration and ration by sampling time. Neither ration protein level nor type influenced average daily gain over the experimental periods (P = .25). Across the PDV, no difference was seen in blood flow (P = .99) or oxygen consumption (P = .84) between rations, suggesting that energy use by the PDV did not differ. Flux of alpha-amino nitrogen (AAN; P < .01) and NH3 (P < .01) across the PDV was highest for the corn based ration. No effect of ration was observed for urea flux (P = .36). Although amount of protein offered differed by 60% between casein based rations, no difference was seen in flux of AAN across casein levels. This disparity between feed protein level and observed AAN flux for casein diets could be explained by observed crude protein intake over the sampling period. Overall, there was no significant effect (P = .19) of protein intake or type on total flux of nitrogenous compounds across the PDV.