Influence Of Exogenous Enzymes On Endogenous Digestive Enzyme Activity And Feed Amino Acid Digestibility Of Poultry

80 eighteen-week-old ISA Brown cockerels were randomly allocated to six groups. Five cockerels were used to determine endogenous amino acid excremental amount as blank experiment. There were fifteen cockerels in each group of other five groups. Five cockerels were used to determine AAD. The other ten cockerels were used for collecting samples to measure endogenous digestive enzyme activities, five of them were slaughtered to collect samples at the end of pre-experiment period, and the others were slaughtered after fasting for 4~h. Cockerels of the first experimental group were fed by common diet without enzyme and the other four group抯 were fed diets with enzyme. In the four groups, five birds were fed diet with enzyme for one to four week pre-experimental period, respectively for a different pre-experimental periods trial, then feaces were collected to determine AAD. All of these groups, the AAD were determined by 揟ME?method. The results showed: (1 )Proventriculus pepsin activities of cockerels were increased but not significantly when birds were fed by the diet with enzyme for different pre-experimental period. Pepsin activities were increased by fasting. (2) There was no significant effect or role on trypsin, amylase activities of duodenum, jejunum and pancreas by enzyme supplementation. Trypsin and aniylase activities ofedistal duodenum were higher or significant higher than that of proximal duodenum.Trypsin specific activities of distal duodenum, jejunum and pancreas were increased, but no effect on the proximal duodenum by fasting. The aniylase activities of duodenum and jejunum were reduced significantly by fasting. (3)Cellulase activities of digestive tract chyme were increased significantly by exogenous enzyme, but also reduced significantly by fasting. Cellulase activities of proventriculus were significant higher than that of duodenum and jejunum. (4) Apparent digestibility and true digestibility of seventeen amino acid were increased in different amount for54different amino acid by exogenous enzyme and various pre-experimental period. The digestibilities of Met, His, Thr, Lys, Ser, Gly and Ala of the ration with exogenous enzyme were higher or very higher than of common diet group(p