Effect of enzyme preparation on egg production, nutrient retention, digestive enzyme activities and pancreatic enzyme messenger RNA expression of late-phase laying hens

This experiment was conducted to study the effect of dietary inclusion of an enzyme preparation including phytase, xylanase, cellulase, α-amylase and acidic protease on egg production, nutrient retention, digestive enzyme activities and pancreatic enzyme mRNA expression. Three hundred and sixty ISA Brown laying hens were randomly allocated to two groups with 6 replicates of 30 birds each and fed a maize–soybean meal diet with or without enzyme supplementation (ES) from 60 to 68 wk of age. There were no differences in hen performance between the two groups. The coefficient of total tract apparent retention (CTTAR) of ether extract (EE) was increased (P<0.05) by ES. Birds fed the diet supplemented with enzymes tended to have higher lipase and protease activity in duodenal and jejunal digesta (P<0.10) than control birds. There were no significant effects of ES on pancreatic enzyme activities. The mRNA expression of amylase in pancreas tended to be downregulated by ES as compared with the control group (P=0.097), whereas that of pancreatic trypsinogen was not affected. It is concluded that ES did not affect productive performance of laying hens, but improved nutrient retention and tended to increase enzyme activities in the intestinal contents. The tendency for lower pancreatic amylase mRNA expression with ES, not coupled with a reduction in pancreatic enzyme activities suggests that amylase expression may be regulated not only at transcriptional level but also at post-transcriptional level.