Performance of Young Calves Fed Soybean Protein Replacers

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Abstract
In 2 12-wk trials soybean protein in calf milk replacers was evaluated. In trial 1, 12 5-day-old Holstein calves were allotted randomly to 3 milk replacers. The diets contained 26% crude protein. In trial 2, 18 calves were used and the diet contained 30% crude protein. In trial 1 period 1 (10-15 days), mean coefficients of apparent digestibility (percent) for milk protein, soy protein concentrate and full fat soy flour replacers were dry matter 92.0, 70.0 and 71.0; protein 90.1, 56.6 and 61.3; fat 88.9, 55.0 and 53.2 and ash 85.8, 62.5 and 61.2. Average daily N retentions were 10.8-1.24 and -0.7 g. Results in period 2 (30-35 days) for digestibilities and N retention showed considerable improvement over those in period 1. In trial 2 period 1, mean coefficients of apparent digestibility (percent) for milk protein, soy protein concentrate and defatted soy flour replacers were dry matter 87.5, 66.6 and 47.9; protein 80.5, 57.2 and 28.5; fat 81.5, 55.9 and 33.5 and ash 83.8, 58.9, 48.4. Average daily N retentions were 10.8, 2.9 and -3.6 g. Results in period 2 for digestibilities and N retention also showed considerable improvement. Calves are able to use soy based replacers more effectively with age.