Combinations of rendered protein meals for growing calves.
Gibb D.J. | Klopfenstein T.J. | Sindt M.H.
Complementary responses between rendered protein meals were investigated in this study. In a preliminary trial using 12 mature wethers in two replications, there was no difference (P > 0.20) in N digestibility between meat and bone meal (MBM; 96.7%), feather meal (FTH; 89.8%), and soybean meal (SBM; 98.7%). In a 112-d growth trial, individually fed calves (n = 120; 230 kg) received graded levels of FTH, MBM, 50:50 MBM-FTH (CP basis), or SBM with or without tryptophan (Trp) supplementation. Additions of Trp increased plasma Trp levels (P < 0.05) but failed to improve efficiency of protein utilization (P > 0.35). Pooled results showed that this efficiency was greater (P < 0.05) for FTH (1.47) than for MBM (1.04), FTH:MBM (.80), or SBM (.66). A trial was conducted to determine whether Trp addition reduces growth response to FTH:MBM (50:50) combinations. Calves (n = 230; 285 kg) were blocked by sex and weight into six replications and received FTH:MBM supplying 35% of the supplemental CP fed alone or with a high or low level of Trp supplement. Negative (urea only) and positive controls were included. Calves receiving FTH:MBM combinations gained faster (P < 0.10) and were more efficient (P < 0.10) than urea-supplemented calves. Performance was not altered by Trp addition. Calves (n = 120; 230 kg) were individually fed in two replications (43 or 48% CP MBM in Replications 1 and 2, respectively) of a growth trial to determine whether there was a complementary response between blood meal (BM) and MBM. There was no complementary response between MBM and BM in either replication. Addition of graded levels of BM linearly (P < 0.01) increased ADG. Results indicate that there is no complementary response between MBM and BM or FTH.
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