GROWTH, DIGESTIBILITY AND NITROGEN RETENTION BY CALVES FED MILK REPLACERS CONTAINING MILK AND SOYBEAN PROTEINS, SUPPLEMENTED WITH METHIONINE

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Abstract
Milk replacers containing zero (all-milk) or 70% of the total protein from a soybean protein concentrate (soy-milk), with or without methionine supplementation, were fed to Holstein calves. Bull calves digested 91 and 89% of the dry matter (P < 0.05), and 87 and 82% of the nitrogen (P < 0.01) supplied by the all-milk and soy-milk replacers, respectively. Nitrogen retention averaged 41% of that consumed, with no difference due to protein source. DL-methionine (0.1% of the dry replacer) did not increase calf growth or nitrogen retention. Heifer calves fed whole milk, the all-milk replacer or soy-milk replacer plus methionine, and hay and concentrates, gained 496, 550 and 526 g/day, respectively, to weaning at 7 weeks of age (treatment means not significantly different at P < 0.05). Weight gains for these three groups of heifers from 7 to 15 weeks of age were 723, 650 and 599 g/day (significant difference between whole milk and soy-milk at P < 0.05), respectively. It was concluded that the soybean protein concentrate could supply a major portion of the protein in milk replacers for rearing dairy calves.