Identification of limiting amino acids in calves receiving two levels of a corn-soybean meal diet above four months of age
1997
Abe, M. (Azabu Univ., Sagamihara, Kanagawa (Japan). Faculty of Veterinary Medicine) | Iriki, T. | Kasahara, K. | Funaba, M.
Eight Holstein bull calves weighing 147 kg initially (16 wk of age) and maintaining reflex closure of the esophageal groove after early weaning were used in a nitrogen (N) balance trial to examine if methionine (Met) and/or lysine (Lys) may be limiting for a ration based on corn, soybean meal (SBM) and rice straw and containing 12.7% CP on an as-fed basis. The trial was conducted in a 4 x 4 Latin square design with two replicates per treatment and 2-wk period. The basal ration was given at two levels of 20 and 27 g/kg BW/d. The N balance was not improved by abomasal administration of 0.111 g/kg BW/d of DL-Met and 0.333 g/kg BW/d of L-LysHCl via the esophageal groove, compared with the administration of iso-nitrogenous L-glutamine, independent of the feeding levels. However, the urinary excretion of purine derivatives was lower at the lower feeding level. The plasma Met concentration was kept higher, and plasma branched chain amino acid concentrations were decreased by administration of DL-Met plus L-LysHCl especially at the lower feeding level. The results suggested that neither Met nor Lys was limiting for the corn-SBM diet above 16 wk of age, or probably DL-Met was too much in this stage of calves
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