Effects of Xylanase on Growth and Gut Development of Broiler Chickens Given a Wheat-based Diet

Abstract

To study the working mechanisms for non-starch polysaccharidases to improve the growth performance of broiler chickens, a 21-day feeding trial was conducted. Two dietary treatments were included: 1) wheat diet (the control); 2) wheat+xylanase diet (xylanase, Allzyme PT, Alltech, Kentucky, USA). There were 8 replicates with 8 birds each for each treatment and the experimental diets were given to birds from hatch. Feed intake and body weight were measured on days 7 and 21. At the same ages, samples were taken for the determination of selected groups of luminal and mucosa-associated bacteria, mucosal morphology, brush-border membrane (BBM) bound enzyme activity and ileal nutrient digestibility. The xylanase supplement increased (p<0.05) body weight gain (BWG) and improved feed conversion ratio (FCR) at the end of the experiment but protein and starch digestibilities were not affected (p>0.05) by xylanase. Up to day 7, xylanase increased the counts of C. perfringens in the ileum and total anaerobic bacteria (TAB) in the caeca (p<0.05, p=0.07, respectively). By day 21, the counts of ileal lactobacilli (p<0.05) and TAB (p=0.07) were lower in birds given the xylanase-supplemented diet than in those on the control diet. No significant differences were observed in the counts of mucosaassociated lactobacilli and coliforms between xylanase treatment and the control at both ages. Villus height at the jejunum was not affected (p>0.05) by the supplement but crypt depth at the same site was reduced at day 7. Also, xylanase tended to increase the concentration of BBM protein (p = 0.09) and the specific activity of sucrase (p = 0.07) at day 21.

Effect of the bacterial or fungal origin of exogenous xylanases supplemented to a wheat-based diet on performance of broiler chickens and nutrient digestibility of the diet

“…Over the past decade, many studies have reported that adding exogenous enzymes, like xylanase, to wheat-based diets may reduce the anti-nutritional effects of AX and consequently improve performance in poultry (Steenfeldt et al 1998;Engberg et al 2004;Meng et al 2005;Yang et al 2008). In this study, broiler chickens fed a wheat-based diet supplemented with exogenous endo-xylanases from 7 to 21 d of age showed significant increase of the final body weight and of the DWG during this period.…”

Evaluation of the effects of sweet potato (Ipomoea batatas (L.) Lam) in broiler diets

“…A similar observation in the present study was the lower colony counts of E.coli in diets with enzymes. Yang, Iji, Kocher, Mikkelsen, and Choct (2008) observed an increase in the number of coliforms and a reduction in the counts of lactobacilli with inclusion of xylanase in wheatbased diets. The chemical composition of the digesta has the influence on the composition of the gut microbial community because different bacterial species have different substrate requirements for growth (Apajalahti, Kettunen, & Graham, 2004)..…”

Performance and morphometry of the intestinal mucosa of laying hens fed diets containing xylanase

“…Additionally, crypt depth values indicate the proliferative activity of epithelial cells (Geyra et al 2001); low crypt depth values suggest reduction in the metabolic cost of intestinal epithelium turnover (Willing & Van Kessel, 2007). Yang et al (2008) verified that xylanase supplementation of diets based on wheat did not change villus height, but reduced jejunal crypt depth of 7-day-old broilers. Mathlouthi et al (2002) reported higher villus height and villus:crypt ratio in the ileum in 22-day-old broilers fed diets based on corn or wheat with inclusion of β-glucanase + xylanase compared with those fed the wheat-based diet with no enzyme supplementation.…”

“…Changes in the intestine by the presence of exogenous enzymes in diets tend to be small, but not only reduction in the size of the intestine and/or release of endogenous enzymes, but also increase of the villi are frequently observed, including in broilers (Yang et al, 2008). Additionally, crypt depth values indicate the proliferative activity of epithelial cells (Geyra et al 2001); low crypt depth values suggest reduction in the metabolic cost of intestinal epithelium turnover (Willing & Van Kessel, 2007).…”