Estimation of ruminal degradation and intestinal availability of crude protein in the animal-origin feedstuffs using mobile nylon bag technique

Ruminal degradation characteristics and intestinal availability of crude protein (CP) in four animal-origin feeds (fish meal, meat meal, viscera meal, feather meal) were estimated by mobile nylon bag technique. Three ruminally and duodenally cannulated Holstein dairy cows (average body wt. 550kg) fed a diet containing 40% concentrate and 60% orchard grass hay on a dry matter (DM) basis. Assuming that the outflow rate of diet in rumen is 5% per hour (k = 0.05), contents of quickly degradable CP (QDP), slowly degradable CP(SDP), and undegradable CP (UDP) in the rumen were 27.6%, 9.4%, 63.0% for fish meal, 34.3%, 28.1%, 37.6% for meat meal, 43.9%, 12.5%, 43.6% for viscera meal, and 14.4%, 15.8%, 69.8% for feather meal, respectively. Intestinal CP degradability was 51.0% for fish meal, 27.2% for meat meal, 37.9% for viscera meal and 56.2% for feather meal. Available UDP in the intestinal tract was contained 288 g, 217 g, 246 g and 423 g per kilograme DM of diet in fish meal, meat meal, viscera meal and feather meal, respectively.