Effect Of Xylanase On Performance And Blood Parameters Of Broilers Based On A Corn-Soybean Meal Diet

Four hundred and forty eight 1-day-old COBB broilers were selected and randomly allocated into 4 treatments with 7 replicates of 16 birds, to investigate effect of different levels of xylanase (0,500,1000,1500U/kg) on growth performance, nutrient utilization, activity of digestive enzyme, development of digestive organ, blood glucose, uric acid, T3, T4, and insulin of broilers to determine optimal xylanase supplementation based on a corn-soybean meal diet.Experiment 1 Effect of xylanase on growth performance and nutrient utilization in broilers. The results showed that:Compared with the control, groups fed with 500,1000, 1500U/kg xylanase decreased feed-gain ratio, respectively, by 5.08%(P<0.05), 5.65%(P<0.05) and 1.69%(P>0.05) for 1 to 21 day broilers, and by 4.95%(P<0.05),5.41% (P<0.05) and 2.70%(P>0.05) for 22 to 42 day broilers. However, feed-gain ratio for 1500 U/kg group is significantly higher than for 500, 1000U/kg groups for both 1 to 21 day and 22 to 42 day broilers. Energy utilization for 500,1000,1500U/kg xylanase groups is significantly higher than for the control, respectively, by 3.67%(P<0.05),3.86%(P<0.05) and 2.44% (P>0.05) for 1 to 21 day broilers, and by 2.80%(P<0.05),2.79%(P<0.05) and 1.77% (P>0.05) for 22 to 42 day broilers. Xylanase had no effect on feed intake, average daily gain and protein utilization in the whole growth period.Experiment 2 Effect of xylanase on activity of digestive enzyme, development of digestive organ and plasma parameters in broilers. The results showed that:Compared with the control,500 and 1000U/kg xylanase significantly increased relative weight of pancreas, muscular stomach, jejunum and ileum and relative length of ileum (P<0.05), but 1500U/kg xylanase had no effect (P>0.05) for 1 to 21 day broilers. Xylanase didn't affect relative weight of glandular stomach and duodenum and relative length of jejunum (P>0.05) for 1 to 21 day broilers. Xylanase significantly decreased relative weight of pancreas, glandular stomach, muscular stomach, duodenum and jejunum and relative length of duodenum and jejunum (P<0.05), but there was no difference in relative weight and length of ileum (P>0.05) for 22 to 42 day broilers. Compared with the control,500,1000,1500U/kg xylanase increased amylase activity, respectively, by 12.33%(P<0.05),9.71%(P<0.05) and 2.29%(P>0.05), and trypsin activity, respectively, by 53.33%(P<0.05),44.19%(P<0.05) and 25.43%(P>0.05), and lipase activity, respectively, by 8.29%,8.53% and 5.29%(P>0.05) for 1 to 21 day broilers. For 22 to 42 day broilers, compared with the control,500,1000,1500U/kg groups increased amylase activity, respectively, by 12.24%(P<0.05),19.36%(P<0.05) and 10.15%(P>0.05), and trypsin activity, respectively, by 15.16%(P>0.05),38.38%(P<0.05) and 23.62%(P>0.05), and lipase activity, respectively, by 13.47%(P<0.05),6.39%(P>0.05) and 1.82%(P>0.05). Compared with the control,500,1000,1500U/kg xylanase increased blood glucose, respectively, by 12.14%(P<0.05),5.40%(P>0.05) and 5.89%(P>0.05), and decreased uric acid, respectively, by 11.54%,23.08% and 5.77%(P>0.05), and increased T3, respectively, by 18.83%,13.64% and 12.67%(P>0.05), and decreased T4, respectively, by 2.23%(P>0.05), 13.28%(P>0.05) and 20.89%(P<0.05), and increased insulin, respectively, by 9.37%(P>0.05),19.64%(P<0.05) and 12.49%(P<0.05)for 1 to 21 day broilers. Xylanase had no effect on blood glucose, uric acid, T3 and T4 (P>0.05), but increased plasma insulin by 4.44%(P>0.05),11.48%(P<0.05) and 6.17%(P>0.05), respectively, for 22 to 42 day broilers.According to the results of this study,500 and 1000U/kg xylanase added to a corn-soybean meal diet for broilers can significantly improve feed-gain ratio, energy utilization, and activity of amylase and trypsin, but had no positive effect on development of digestive organ, especially for 22 to 42 day broilers. High level of xylanase(1500U/kg)had no further improvement, even tended to decrease these indexes. These results indicated that optimal supplementation of xylanase in a corn-soybean meal diet for broilers was 500U/kg in the condition of this experiment.