Effect of soybean, feather and hair meal protein on dry matter, energy and nitrogen utilization by growing steers.

The effect of soybean meal, feather meal and hair meal on dry matter (DM), energy and nitrogen (N) utilization by growing steers was evaluated in three metabolism studies. Feather meal (FM) and hair meal (HM) protein were substituted for 25, 50 and 75% (Exp. 1, 2 and 3, respectively) of the soybean meal (SBM) protein in pelleted protein supplements and fed in whole-shelled, corn-ground corncob complete mixed diets. Rumen and blood samples were collected at the end of each study to compare the effect of each protein source on rumen ammonia and plasma urea nitrogen concentrations. There were no significant differences (P>.05) in DM digestibility or digestible energy (DE) values in any of the experiments. Steers receiving FM of HM protein in Exp. 1 and 3 excreted significantly (P<.05) more fecal N than did steers receiving SBM. Significant differences (P<.05) were observed in urinary N excretion values in all three experiments. Apparent N digestibilities were significantly lower (P<.05) for FMand HM-fed steers in Exp. 3. Feather meal (Exp. 1) and HM (Exp. 1 and 3) resulted in significantly more absorbed N retention than did SBM. Expression of the N balance data on a metabolic weight basis resulted in significantly less (P<.05) urinary N excretion and significantly higher (P<.05)fecal and retained N values for steers fed FM or HM. Rumen ammonia concentrations were significantly higher for steers fed SBM at 1, 2, 4 and 6 hr postfeeding in Exp. I and 3. Plasma urea N