Supplementation of β-Mannanase in Diet with Energy Adjustmenton Affect Performance, Intestinal Morphology and Tight Junction Proteins mRNA Expression in Broiler Chickens

摘要

The objective of this study was to assess the effects of commercial β-mannanase enzyme supplementation in low-energy corn-soybean meal diets on performance, intestinal morphology and mRNA expression of intestinal tight junction proteins in 1-21 days broiler chickens. The 1800, 1 day old broiler chicks were divided into 5 treatment groups, 6 pens in each treatment. The study was performed in a randomised complete block design. The 5 treatments were Positive diet Group (PG) with basal energy level, Negative diet Group (NG) with lower energy of 502.08 kJ kg-1 and other groups supplemented with 150, 300 and 450 mg kg-1 β-mannanase based on NG. Decrease of energy in NG resulted in loss of the Average Daily Gain (ADG) (p<0.05) and Feed Conversion Ratio (FCR) (p<0.05). Based on the NG, supplementation with β-mannanase in diet significantly improved the Average Daily Gain (ADG) (p<0.05) and Feed Conversion Ratio (FCR) (p<0.05) of birds. ADG of groups with enzyme and lower energy reached to the level of PG. Supplementation with 300 g ton-1 β-mannanase increased the villus height of the small intestine (p<0.05) and 450 g ton-1 β-mannanase significantly decreased the crypt depth (p<0.01). The addition of β-mannanase at 150, 300 and 450 g ton-1 to the diets increased the ratio of crypt depth to villus height of the duodenum and jejunum in birds (p<0.01). The ratio of crypt depth to villus height of the ileum was also increased with 300 and 450 g ton-1 β-mannanase supplementation compared to the low-energy diet group (p<0.01). Chicks fed diet with the β-mannanase showed an increased mRNA expression of ZO-1 in the duodenum compared with the low energy diet (p<0.05). Supplementation with 300 and 450 g ton-1 β-mannanase to the diets enhanced the mRNA expression of Occludin and ZO-1 in the jejunum (p<0.05) and 300 g ton-1 β-mannanase increased enhanced the mRNA expression of Occludin and ZO-1 in the ileum (p<0.05). Thus, the addition of β-mannanase to low energy diets improved the performance, gut morphology and mRNA expression of intestinal tight junction proteins.