DISTRIBUTION OF ACTIVITY OF HYDROLYTIC ENZYMES IN THE DIGESTIVE-TRACTOF RABBITS

Activities of twelve hydrolytic enzymes in the digestive tract of youn g rabbits before weaning (4 weeks old) and adult rabbits (3 months old ) were measured. The principal digestive enzymes in both groups of rab bits appeared to be amylase (EC 3.2.1.1), maltase (EC 3.2.1.20), pecti nase (EC 3.2.1.15) and proteinases. The stomach of young rabbits conta ined most of the lipolytic activity and 45.7 % of the total proteolyti c activity of the digestive tract. The highest specific activities (pe r g digesta) of amylase, maltase and proteinase in young rabbits were found in the small intestine. Total activities (per segment) of amylas e and maltase in the small intestine and the caecum were similar. Acti vities of cellulase (EC 3.2.1.4), inulinase (EC 3.2.1.7) and beta-gluc osidase (EC 3.2.1.21) were low and activity of pectinase was fairly hi gh in all segments of the digestive tract. The highest activity of ure ase (EC 3.5.1.5) was found in the caecum. Enzymic profiles of the colo nic chymus resembled those of the caecum. Total hydrolytic activity wa s lower in the colon than in the caecum. Specific activities of amylas e and invertase (EC 3.2.1.26) were lower and those of inulinase and la ctase (EC 3.2.1.23) higher in 4-week-old rabbits than in 3-month-old r abbits. Gastric proteinase represented almost half of the total proteo lytic activity of the digestive tract, whereas lipolytic activity of g astric contents was not found in measurable quantities in adult rabbit s. The caecal contents of adult rabbits contained most of the total ac tivity of lipase (EC 3.1.1.3), cellulase, xylanase (EC 3.2.1.32), pect inase, lactase, invertase, beta-glucosidase and urease present in the digestive tract. The presence of microbial enzymes (pectinase, cellula se, xylanase, inulinase and urease) in non-fermentative segments of th e digestive tract reflects the reingestion of caecal contents during c oprophagy.