PREDICTION OF INTESTINAL DIGESTIBILITY OF UNDEGRADED PROTEIN IN THE RUMEN BY ENZYMATIC METHOD

The investigation was focused on the choice of a suitable enzymatic me thod to determine digestibility of dietary undegraded protein in the r umen of ruminants. The trial involved a set of feeds - n = 45 (Tab. II I) - that comprised fresh forage, grains and feeds of animal source. S tatistical analyses to compare two modified methods (Antoniewicz et al ., 1992; Setala et al., 1984) were applied to a smaller set of feeds ( n = 16). The tested enzyme in feeds was pancreatin (activity 4 x USP, concentration 600 mg/l phosphate buffer, pH 7.4), and trypsin (40 U/mg ) - chymotrypsin (350 U/mg) at a concentration of 2 g/l. The enzymatic method has two stages. In the first stage, feed is incubated for 16 h ours in the rumen, then it is used for direct enzymatic determination of intestinal digestibility of undegraded protein in the rumen. The re sults of this trial were compared with the more complicated mobile bag method. A relationship of these values was described by the coefficie nt of correlation (r) for pancreatin r = 0.945 (Tab. II, Fig. 2) and f or trypsin-chymotrypsin r = 0.908 (Tab. II, Fig. 1) for the see of fee ds n = 16 in three replications. The trial with pancreatin continued w ith the set of feeds n = 45 and the results were again compared with t he mobile bag method. The relationship between the values determined b y the mobile bag method (y) and the values determined by pancreatin (x ) was represented by linear regression for the whole set of feeds (Fig . 3). The enzymatic method using pepsin and pancreatin correlates with dietary protein digestibility and is suitable to determine digestibil ity of dietary undegraded protein in ruminants.