Roasted fullfat soybean as an ingredient of milk replacers for goat kids

Abstract

The present work was aimed at studying simple methods for processing fullfat soybean, and at designing soy-based milk replacers suitable for goat kids. Soybean was roasted at 100°C for 10 (HSF10) or 30 (HSF30) min. The residual antitryptic activity and immunoreactive glycinin and β-conglycinin, respectively, were 40, 17 and 5% for HSF10, and 20, 6 and 3% for HSF30, of those in raw soybean. Milk replacers containing 24% CP and 22% fat were prepared. In the control diet, skim milk powder and sweet whey provided 95 and 5% of total protein, respectively. In the soy-based diets, 45% of total protein was from either the HSF10 or the HSF30 flour, the remainder being provided by skim milk powder and sweet whey (45 and 10% of total protein, respectively). These diets were given as liquid milk replacers to 20 goat kids ( n=6, 8 and 6 for control, HSF10 and HSF30 treatments, respectively) between 14 and 50 days of age. Nutrient digestibility and N balance were measured twice over 5 days starting at 26 and 40 days of age. Growth and DM intake were not significantly different between treatments. The digestibility of N was lower for the soy-based diets as compared with the control diet. It did not change significantly over time for the control and HSF10 diets (average values of 0.915 and 0.67, respectively) but it increased significantly from 0.70 to 0.80 for HSF30 between the two measurement periods. Direct skin tests carried out with soybean protein extracts after the second measurement period revealed only delayed reactions to HSF10 extracts in the HSF10 group. Roasting fullfat soybean at 100°C for 30 min appeared to provide a milk replacer ingredient nutritionally more acceptable for rearing kids than roasting for 10 min.