Estimation of true intestinal digestibility of dry matter, nitrogen and amino acids of cowpea and silverleaf desmodium forage legumes and <i>Brachystegia spiciformis</i> (musasa) browse legume

Abstract

True intestinal digestibility of dry matter (DM), rumen-undegraded dietary protein (UDP) and amino acids of cowpea, silverleaf desmodium and Brachystegia spiciformis (musasa) were estimated. The true intestinal digestibility was calculated as the difference between the content of a bag that was preincubated in the rumen for 12, 24 and 48 h and was recovered in the faeces. Significantly higher DM and nitrogen disappearance rate in the rumen, postruminally and throughout the whole tract were found for cowpea than for silverleaf desmodium and musasa. Total amino acids or true nitrogen digestibility values of silverleaf desmodium and musasa tended to be higher than in cowpea.  The true digestibilities for the individual amino acids in the different undegraded protein sources showed significant differences. The true  intestinal digestibility of DM, nitrogen and amino acids in the mobile bags after 24 h and 48 h of preincubation in the rumen were higher for  silverleaf desmodium and musasa, than in cowpea. Musasa and silverleaf desmodium provided little rumen-degradable nitrogen and supplied UDP to the intestines. The UDP supplied postruminally would  be used for productive processes such as milk production and growth.

African Journal of Range & Forage Science 2009, 26(2): 51–57