title: Effect of protein source and lasalocid on nitrogen digestibility and growth by ruminants.
abstract: Protein supplements having either a high (soybean meal, SBM) or low (escape protein, EP) extent of ruminal N degradability with or without lasalocid (L) were evaluated in digestion and growth trials. The SBM supplement included soybean meal while EP was a combination of dehydrated alfalfa and distillers dried grains. Nitrogen digestibility of SBM supplements was consistently higher than EP supplements when evaluated with two lamb trials. Digestibility of N was improved 8% in trial one (64.9 vs 60.3%) and 27% in trial two (66.3 vs 52.3%) with SBM vs EP. The addition of L to the supplements improved N digestibility by 6% in trial one (64.5 vs 60.6%) and 13% in trial two (62.9 vs 55.7%). No interactions between protein source and L were measured in either trial. Dry matter digestibility was not changed by protein source or L in either trial. Rumen propionate was increased and acetate to propionate ratio decreased when L was fed. Plasma urea N was lower over a 24 h sampling period when lambs were fed EP supplements compared with SBM supplements (11.07 vs 16.44 mg/100 ml); however, L did not appear to consistently alter the values. When steers were supplemented with the same protein sources during a 105-d winter pasture trial daily gains were not affected (P greater than .10) by either protein source or L (.429, .495, .476 and .514 kg/d for SBM, SBM+L, EP and EP+L, respectively) although numerically there did not appear to be main effect improvements due to EP and L.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001806:Blood Urea Nitrogen; D001835:Body Weight / Q000187:drug effects; D002417:Cattle / Q000502:physiology*; D004044:Dietary Proteins / Q000494:pharmacology*; D004063:Digestion / Q000187:drug effects; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005503:Food Additives; D007832:Lasalocid / Q000494:pharmacology*; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism; D012756:Sheep / Q000502:physiology*
chemical_list: D004044:Dietary Proteins; D005232:Fatty Acids, Volatile; D005503:Food Additives; D009584:Nitrogen; D007832:Lasalocid