EFFECT OF AGE AND EXOGENOUS AMYLASE AND PROTEASE ON DEVELOPMENT OF THE DIGESTIVE-TRACT, PANCREATIC-ENZYME ACTIVITIES AND DIGESTIBILITY OF NUTRIENTS IN YOUNG MEAT-TYPE CHICKS

Day-old male meat-type chicks were fed a commercial starter diet suppl emented with 2 levels of enzyme preparations containing amylase and pr oteases up to 14 d of age. Enzyme supplementation had no significant e ffect on feed intake or growth rate, and was accompagnied by a signifi cant decrease in gizzard content and small intestine weight. The intes tine contents increased and this increase was accompanied by a signifi cant decrease in its pH. Enzyme supplementation depressed the activity of chymotrypsin in the pancreas and the 'activity of amylase, trypsin and chymotrypsin in the intestinal contents. Some carry-over effects were observed on d 42, 4 weeks after the cessation of the enzyme suppl ements. These were mainly a significant depression in the activity of trypsin in the intestinal contents. In a balance study, diets suppleme nted with 0,250 and 1000 mu g/kg enzyme preparations were supplied. Ex ogenous enzyme supplements had no significant effect on the digestibil ity of all the nutrients studied except for the highest level of enzym e supplementation, which improved slightly but consistently the digest ibility of amino acids. Some age effects were observed, mainly a decre ase in the digestibility of fat and starch, and in the ME of the diet from weeks 1 to 2 followed by an increase during week 3. Protein diges tibility and retention of nitrogen decreased with age.