Performance of young calves fed soybean protein replacers

In two 12-wk trials we evaluated soybean protein in calf milk replacers. In trial 1, twelve 5-day-old Holstein calves were allotted randomly to three 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 to 15 days), mean coefficients of apparent digestibility (%) for milk protein, soy protein concentrate, and full fat soy flour replacers were dry matter 92.0, 70.0, 71.0; protein 90.1, 56.6, 61.3; fat 88.9, 55.0, 53.2;; and ash 85.8, 62.5, 61.2. Average daily nitrogen retentions were 10.8, -1.24, and -.7 g. Results in period 2 (30 to 35 days) for digestibilities and nitrogen retention showed considerable improvement over those in period 1. In trial 2 period 1, mean coefficients of apparent digestibility (%) for milk protein, soy protein concentrate, and defatted soy flour replacers were dry matter 87.5, 66.6, 47.9; protein 80.5, 57.2, 28.5; fat 81.5, 55.9, 33.5; and ash 83.8, 58.9, 48.4. Average daily nitrogen retentions were 10.8, 2.9, and -3.6 g. Results in period 2 for digestibilities and nitrogen retention also showed considerable improvement. Calves are able to use soy based replacers more effectively with age.