Effect of Roasting Temperatures on Soybean Utilization by Young Dairy Calves

Abstract

Diets containing soybeans roasted at different temperatures were fed to investigate effects on growth and feed consumption by calves. In trial 1, Holstein calves (n = 71) were used from birth to 10 wk of age. TItree of the diets contained 18% CP and soybeans roasted to achieve exit temperatures of 99, 127, or 143C and air cooled immediately after they exited the roaster; the fourth diet contained 15% CP and soybeans roasted at 127"C. Calves fed the diet containing soybeans roasted at 143C consumed more feed, gained more BW, and were more efficient in converting feed and energy to gain than those fed soybeans roasted at 99 or 127C. Performance was intermediate by calves fed the diet containing 15% CPo In the second trial, 84 Holstein calves were used from 0 to 8 wk of age and were fed diets containing soybeans that had been roasted to achieve exit temperatures of 132, 146, or 163"C, followed by 30 min of steeping. Performance of calves fed soybeans processed at 146"C was superior to that of calves fed soybeans processed at 132 or 163C. Rumen-undegradable intake protein, determined by a protease method, increased with increasing roast-