RESUMO
The effects of beta-glucanase (550 U g(-1)) and xylanase (800 U g(-1)) supplementation on the nutrient digestibility and metabolizable energy of egg production, egg quality intestinal morphology of the broiler chicks and layer hens fed hull-less barley-based diets were examined in three similar experiments. The results of this study showed that the inclusion of beta-glucanase and xylanase in the hull-less barley based diets had no significant improvement on the growth performance of broiler, feed conversion ratio. The results of this experiment showed that beta-glucanase and xylanase had negative effects on egg shell quality as reduced egg shell weight (4.6%) and egg shell thickness (5.32%). The addition of beta-glucanase and xylanase had also no effects on yolk color and Hugh units of eggs either. The results also demonstrated that beta-glucanase and xylanase supplementation did not improve the metabolizable energy, organic matter, protein and starch digestibility of the diet contained hull-less barley. The addition of glucanase and xylanase to the diets significantly reduced villus height, villus width, crypt depth, villus height: crypt depth ratio and goblet cell numbers of the duodenum and jejunum of small intestine compared with the control group. But, the numbers of goblet cells were more in the jejunum than in duodenum of small intestine. On the other hand, these enzymes reduced villus width and crypt depth of the ileum while increased villus length of the ileum receptivity. The goblet cells numbers in the villi of the ileum of birds fed the hull-less based diet; with exogenous enzyme were significantly higher than those in the jejunum and duodenum section of small intestine of layer hens. Goblet cells are responsible for the secretion of mucin that is used for the mucinous lining of the intestinal epithelium. Further studies are needed to evaluate the effects of exogenous enzyme on the nutrient digestibility, metabolizable energy, intestinal morphology and microflora activity of intestine of the broiler chickens and layer hen diet.
