Effect of moist heat treatment on in-vitro degradability and ruminal escape protein and amino acids of mustard meal

A study was conducted to determine the effects of moist heat treatment (127 degrees C, 117 kPa steam pressure) for 10 min on protein fractions and in- vitro crude protein (CP) degradability of mustard meal. Rumen undegraded pr otein (RUP) and amino acid disappearance of unheated, and heated, mustard m eal were measured following 12 h of rumen incubation using two ruminally fi stulated cows. Intestinal availability of RUP was estimated using an enzyma tic (pepsin-pancreatin) procedure. Heat treatment reduced (p<0.05) protein solubility and increased (p<0.05) neutral detergent insoluble CP without af fecting acid detergent insoluble CP of mustard meal. Relative to the contro l, heated mustard meal had a lower (p<0.05) effective in-vitro CP degradabi lity (445.2 vs. 746.8 g kg(-1) of CP) and a higher (p<0.05) ruminal escape CP (615.1 vs. 120.2 g kg(-1) of CP) value. Amino acid composition was not a ffected by heat treatment except for the concentration of arginine and lysi ne which was lower (p<0.05) in heated than in unheated mustard meal. Disapp earance of all amino acids following 12h of rumen incubation was lower (p<0 .05) in unheated than in heated mustard meal. Heat treatment increased (p<0 .05) the amount of protein available for digestion in the small intestine f rom 75.7 to 518.1 g kg(-1) of CP. It was concluded that moist heating of mu stard meal for 10 min will reduce ruminal CP and amino acid degradability w ithout compromising the intestinal availability of ruminal undegraded prote in. (C) 1999 Elsevier Science B.V.