| Abstrakt: |
Four experiments were conducted to evaluate the nutritional quality of crambe meals in which the endogenous enzyme, thioglucosidase (TGSase), was inactivated by either microwave energy or hot water. In Exp. 1, 40 male rats (74 g) were fed diets containing one of four protein sources (casein or one of three types of crambe meal with hulls) for 13 days. All crambe diets contained 10% crude protein (CP). The feeding of 25% untreated meal resulted in the deaths of four rats in 3 days. Inactivation of the TGSase of crambe seeds by microwave or hot water reduced the toxicity of the crambe meal. However, rats fed these meals lost weight and had a negative feed efficiency. In Exp. 2, 30 male rats (66 g) were fed one of two types of crambe meal or a casein control for 16 days. All diets contained 10% CP. Crambe seeds (15% moisture) subjected to microwave heating and subsequent water extraction of glucosinolates proved to have the same nutritional quality as the hot water-extracted crambe meal (seeds boiled in water for 3 min before water extraction of the glucosinolates) and the casein control. In Exp. 3, 120 male rats (71 g) were assigned to 12 treatments for 21 days. The treatments were four levels of crude protein (10.0, 12.5, 15.0 and 17.5%) from three sources (soybean meal, hot water-extracted crambe meal [HWCM] and micro waved crambe meal [HWCM]). The glucosinolates of both crambe meals were water extracted after TGSase inactivation. MWCM fed to rats at 12.5, 15.0 and 15.5% CP was of poorer nutritional quality than HWCM or soybean meal (SBM). The 10% CP HWCM diet was superior in quality to the 10% protein SBM and MWCM diets. There were no differences in the performance of rats fed HWCM or SBM at 12.5, 15.0 or 17.5% protein. In Exp. 4, 24 male rats (42 g) were used to examine the effects of amino acid supplementation of a 10% CP HWCM. The treatments were a 10% CP HWCM diet and this diet supplemented with .25% L-lysine-HCl and(or) .10% DL-methionine. The experiment lasted 27 days. No improvement in growth or feed efficiency was observed from supplementation with any of the amino acids, indicating that neither lysine nor methionine was first limiting in the diet. The data from these experiments indicate that the protein of crambe meal is of high quality for rats. The endogenous TGSase enzyme must be inactivated and the glucosinolates removed before feeding. |
