Limiting amino acids for early-weaned calves fed a corn and soybean meal diet and response of plasma free amino acid concentrations to abomasally supplemented amino acids
1997
Abe, M. (Azabu Univ., Sagamihara, Kanagawa (Japan). Faculty of Veterinary Medicine) | Sekine, S. | Funaba, M. | Iriki, T.
Holstein bull calves weaned at 6 wk of age were used in two nitrogen (N) balance experiments to identify limiting amino acids for a ration based on corn, soybean meal and rice straw and containing 14.5% CP of DM. The calves were trained to maintain reflex closure of the esophageal groove throughout the experiments that started from 8 wk of age. In experiment 1, three levels (0, 0.022 and 0.111 g/kg BW/d) of DL-methionine (DL-Met) were administered through the esophageal groove to 9 calves in a 3 x 3 Latin square design with three replicates and 10 d-period. In Experiment 2, 18 calves were divided into 3 groups, and allotted to three treatments: abomasal administration of DL-Met (0.111 g/kg BW/d), DL-Met with L-tryptophan (L-Trp), or DL-Met with L-Trp and L-Lys monohydrochloride (L-LysHCl) for 2 wk each. The amount of supplemental N was adjusted with L-glutamine among treatments in every experiment. As a result, the N balance was improved, and plasma concentrations of branched-chain amino acids (BCAA) were decreased, by the highest dose of DL-Met in Experiment 1. In Experiment 2, however, administration of L-LysHCl and L-Trip in addition to DL-Met improved N balance without decrease in plasma BCAA concentrations
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