Effect of Roasting Temperatures on Soybean Utilization by Young Dairy Calves

¹ Department of Animal Sciences and Industry Kansas State University Manhattan 66506
² ALTECA, Ltd. Manhattan, KS 66502

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. Three of the diets contained 18% CP and soybeans roasted to achieve exit temperatures of 99, 127, or 143°C 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 143°C consumed more feed, gained mote BW, and were more efficient in converting feed and energy to gain than those fed soybeans roasted at 99 or 127°C. Performance was intermediate by calves fed the diet containing 15% CP. 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 163°C. Rumen-undegradable intake protein, determined by a protease method, increased with increasing roasting temperature, but unavailable protein, as calculated from ADIN, was high for soybeans roasted at 163°C. Lipase activity decreased with increasing roasting temperature and was absent for soybeans toasted at 163°C. Roasting temperatures that resulted in superior calf performance corresponded to corrected undegradable intake protein (undegradable intake protein minus indigestible intake protein) of 50 to 60% and a trace of lipase activity.

Key Words: calves • starter diets • soybeans • roasting temperatures

Submitted on September 21, 1992
Accepted on December 28, 1992