Effect Of Dietary Xylan Level And Xylanase Supplementation On Nutrient Digestibilties In Piglet Diets

Five digestive experiments were conducted to study the piglet tolerance to dietary xylan and the effect of xylanase supplementation on nutrient digestibilties in five diets.The xylan contents of the five diets were 4. 19%, 5.33%, 6.47%, 7.25% and 8.44%, respectively. Wheat and wheat bran were used to replace corn and soybean meal in corn-soybean meal based diet so as to design different levels of dietary xylan. Each of five digestive experiments (Each level of dietary xylan) included five treatments,which were respectively given the diets without enzyme and with four levels of xylanase. As the increase of xylan contents in five diets, xylanase supplementations were enhanced accordingly. 24 of healthy Landrace X Rongchang crossbred piglets (initial body weight about 15kg) were allotted randomly into five treatments in every experiment. The control treatment consisted of 4 replicates, and each of the other treatments consisted of 5 replicates with one piglet per replicate. The results are as follows.(1) As the increase of the xylan contents in piglet diets, nutrient digestibilities decreased. When dietary xylan content increased from 4. 19% to 8.44%, nutrient digestibilities were significantly decreased. Digestibilities of crude protein, organic matter, calcium, phosphorus, acid detergent fibre(ADF) and energy decreased by 6.21%, 4.59%, 26.38%, 11.54%, 27.84% and 5.50%, respectively. Regression analysis showed that there were linear relationships between nutrient digestibilities and dietary xylan contents, and that all regressive coefficients were negative. When dietary xlyan content increased 1 percentage, digestibilities of crude protein, organic matter, calcium, phosphorus,ADF and energy decreased 0.94, 0.73, 4.07, 1.91, 3.34 and 0.76 percentage, respectively.(2)The influence of xylanase supplementation on nutrient digestibilities were related to the xylan contents in piglet diets. Xylanase supplementation had no effect on nutrient digestibilities of the diets containing xylan contents of 4.19%(corn-soybean meal diet), 5.33% and 6.47%. When dietary xylan content increased to 7. 25%, xylanase supplementation increased nutrient digestibilities. Compared with the group without enzyme, average digestibilities of the groups with enzymes for crude protein, organic matter, calcium, phosphorus, ADF and energy were enhanced by 4.46%, 1.61%, 10. 19%, 7.61%, 4.28% and 2.44%, respectively. Xylanase supplementation also improved nutrient digestibilities of the diet containing 8.44% xylan to similar extent. Compared with the group without enzyme, average digestibilities of the groups with enzymes for crude protein, organic matter, calcium, phosphorus, ADF and energy were enhanced by 2.92%, 1.05%,, 5. 80%, 5.15%, 2. 36% and 0.84%, respectively.This trial showed that about 15kg piglets could tolerate some content of dietary xylan, and as dietay xylan content increased, nutrient digestibilities were decreased to a different degree. Xylanase supplementation did not improve significantly nutrient digestibilities until dietary xylan content reached or exceeded 7. 25%.