RUMEN DEGRADATION AND INTESTINAL DIGESTION OF CRAMBE AND OTHER OILSEED BY-PRODUCTS IN DAIRY-COWS

The by-products of several oilseeds (Crambe abyssinica, Euphorbia lagascae, Dimorphotheca pluvialis and Limnanthes alba) were analysed for their chemical composition, and studied for in vitro digestibility, rumen degradation and post-rumen digestion in dairy cows. In situ nylon bag and mobile bag techniques were employed for rumen and intestine incubations. Rapeseed and soya-bean meals were used as reference feeds. The results indicated that some of these oilseed by-products were potentially useful feed ingredients. Properly dehulled and defatted crambe meal showed the highest potential degradability of the samples examined. Potential rumen degradabilities (100 minus the undegradable fraction) of organic matter for crambe meal, crambe cake, crambe hulls, euphorbia meal, dimorphotheca meal, limnanthes cake, rapeseed and soya-bean meals were 96%, 73%, 43%, 62%, 67%, 84%, 85% and 95%, respectively. The intestinal digestibility of rumen-undegraded nutrients was largely dependent on their rumen residence time, but the fraction of undigestible protein was not. The total tract digestibilities of sample protein (100 minus undigestible fraction) were determined as 98%, 95%, 97%, 88%, 79% and 92% for crambe meal, crambe cake, euphorbia meal, dimorphotheca meal, limnanthes cake and rapeseed meal, respectively.