Influence of dietary carbohydrases, individually or in combination with phytase or an acidifier, on performance, gut morphology and microbial population in broiler chickens fed a wheat-based diet

The objective of this study was to examine the effects of dietary carbohydrases(xylanase and b-glucanase; XG), individually or in combination with phytase or acidifier on the growth performance, carcass attributes, intestinal microbial counts and morphology in broiler chickens fed a wheat-based diet. A total of 240 one-day-old male broiler chicks were randomly allocated into 4 treatment groups with 6 replicates of 10 birds each. The dietary treatments included a basal diet, the basal diet with an enzyme complex containing XG, XG plus a microbial phytase(XG + P) and XG plus acidifier(XG + A). The results indicated that feed conversion ratio(FCR) was improved in broiler chickens which received XG + A during the entire production period(1 to 35 d) of the trial(P < 0.05). The broiler chickens fed XG + P had lower feed intake compared with the control group at 29 to 35 d of age. The experimental treatments had no effect on the body weight gain of broiler chickens. In carcass traits, except for spleen(P < 0.05), the dietary treatments had no effects on the carcass characteristics of broiler chickens. The birds which received diets supplemented with XG and XG + A had a lower weight of the spleen compare with the control. Addition of XG in combination with phytase(XG + P) resulted in a decrease in ileal enumeration of Escherichia coli at 35 d of age(P < 0.05). However, dietary treatments did not alter the population of ileal Lactobacilli in broiler chickens. Supplementing carbohydrases with phytase and acidifier(XG + P and XG + A) significantly increased the intestinal villus length at 35 d of age(P < 0.05). In conclusion, the present study demonstrated that supplementation of the wheat-based diet with a combination with carbohydrases and acidifier(XG + A) improves FCR in broiler chickens. Furthermore, combinations of carbohydrases with phytase(XG + P) and with acidifier(XG + A) decrease the E. coli counts and increase the villus length in broiler chickens.

Non-starch polysaccharide-degrading enzymes may improve performance when included in wheat- but not maize-based diets fed to broiler chickens under subclinical necrotic enteritis challenge

The present study investigated whether supplementing fibre-degrading enzymes can ameliorate the severity of subclinical necrotic enteritis(NE)in broiler chickens offered wheat-or maize-based diets.A total of 1,544 mixed-sex broiler chickens were assigned to 16 experimental treatments as a 2×2×4 factorial arrangement of treatments.The factors were the following:NE challenge,yes or no;diet type,wheat-or maize-based;and enzyme supplementation,control(no enzyme),family 10 xylanase(XYN10),family 11 xylanase(XYN11)or b-mannanase(MAN).Each treatment was replicated 6 times,with 16 birds per replicate pen.A three-way challenge×diet type×enzyme interaction occurred for body weight at 21 d of age(P=0.025)and overall feed conversion ratio(P=0.001).In the non-challenged birds fed the wheat-based diet,supplementing MAN increased d 21 body weight compared to the control.In challenged birds fed the maize-based diet,supplemental XYN11 impeded body weight and overall FCR compared to the control.Birds offered the maize-based diet presented heavier relative gizzard weights at both 16 and 21 d of age(P<0.001)and reduced liveability(P=0.046)compared to those fed the wheatbased diet.Enzyme supplementation reduced ileal and jejunal digesta viscosity at 16 d of age only in birds fed the wheat-based diet(P<0.001).XYN11 increased ileal digesta viscosity in birds fed the maizebased diet,and MAN reduced it in birds fed the wheat-based diet at 21 d of age(P=0.030).Supplementing XYN11 improved ileal soluble non-starch polysaccharides(NSP)digestibility in birds fed the wheat-based diet compared to non-supplemented birds(P<0.001).Birds fed the wheat-based diet displayed a higher abundance of Bifidobacterium,Lactobacillus and Enterobacteriaceae and butyric acid in the caeca at 16 d of age compared to birds fed the maize-based diet(P<0.05).In conclusion,supplemental XYN11 exacerbated the negative impact of NE on growth performance in birds fed the maizebased diet.Supplementing wheat-based diets with fibre-degrading enzymes ameliorates production losses induced by NE.