Diet medication and beta-glucanase affect ileal digesta soluble betaglucan molecular weight,carbohydrate fermentation,and performance of coccidiosis vaccinated broiler chickens given wheatbased diets

Exogenous enzymes as alternatives to feed antibiotics in poultry has become an emerging research area with the emergence of antibiotic resistance.The objective was to evaluate the effects of diet medication(antibiotics)andβ-glucanase(BGase)on digesta solubleβ-glucan depolymerization,carbohydrate fermentation,and performance of coccidiosis-vaccinated broiler chickens fed wheat-based diets.A total of 1,782 broilers were raised on litter floor pens,and each treatment was assigned to 1 pen in each of the9 rooms.The 3 dietary treatments were based on wheat as the sole grain(control,control+medication and control+0.1%BGase),and the birds were fed the respective treatments ad libitum from 0 to 33 d.Treatments were arranged in a randomized complete block design and analyzed as a one-way ANOVA.Beta-glucanase reduced the peak molecular weight,weight average molecular weight(Mw)and maximum molecular weight for the smallest 10%β-glucan molecules(MW-10%)in ileal digesta at d 11and 33,whereas diet medication reduced Mw and MW-10%at d 33 compared to the control(P<0.01).Beta-glucanase and medication reduced the ileal viscosity at d 11 compared to the control(P=0.010).Ileal propionic acid concentration at d 11 and caecal total SCFA,acetic,and butyric acid concentrations at d 33 were lower in the BGase-supplemented diet than in the control(P<0.05).The BGase-added diet had higher duodenal p H compared to the control at d 33(P=0.026).The effect of medication on carbohydrate fermentation was minimal.Diet medication increased weight gain after d 11,whereas BGase increased the gain for the total trial period compared to the control(P<0.001).Feed intake was not affected by the dietary treatment.Medication and BGase improved feed efficiency after d 11 compared to the control(P<0.001).The response to diet medication was larger than BGase,considering weight gain and feed efficiency after d 11(P<0.001).In conclusion,diet medication and BGase depolymerized high molecular weight ileal solubleβ-glucan and increased overall bird performance.Dietary BGase may benefit bird health in broilers fed wheat-based diets without medication.

Hulless barley and β-glucanase affect ileal digesta soluble β-glucan molecular weight and digestive tract characteristics of coccidiosis-vaccinated broilers

Exogenousβ-glucanase(BGase)in barley-based feed has been shown to reduce digesta viscosity in chickens,and thereby improve performance.Less well studied is the potential for BGase to convert barleyβ-glucan into low molecular weight carbohydrates,which might influence digestive tract function and enteric disease.Coccidiosis-vaccinated broiler chickens were fed graded levels of hulless barley(HB)and BGase to determine their effects onβ-glucan depolymerization and digestive tract characteristics.Broilers were fed highβ-glucan HB(0%,30%and 60%replacing wheat)and BGase(0%,0.01%and 0.1%)in a 3×3 factorial arrangement.A total of 5,346 broilers were raised in litter floor pens and vaccinated for coccidiosis on d 5.Each treatment was assigned to 1 pen in each of 9 rooms.The significance level was set at P≤0.05.At both 11 and 33 d of broiler ages,peak molecular weight ofβ-glucan in ileal digesta decreased with increasing BGase for 30%and 60%HB.The maximum molecular weight for the smallest 10%β-glucan molecules(MW-10%)decreased with BGase at both ages for 30%and 60%HB;for birds fed 0%HB,only 0.1%BGase decreased MW-10%.The 0.1%BGase increased caecal short chain fatty acids(SCFA)compared to the 0.01%BGase at d 11 only for the 60%HB.Ileal pH increased with increasing HB and BGase at d 11 and 33.Caecal pH was lower for 0.1%BGase than 0%BGase for 60%HB at d 11.Relative mRNA expression of interleukin 6(IL-6)and IL-8 in the ileum increased with 0.1%BGase at d 11 and 33,respectively,whereas expression of ileal mucin 2(MUC2)decreased with 0.1%BGase at d 33.In the caeca,interactions between HB and BGase were significant for monocarboxylate transporter 1(MCT1)and mucin 5AC(MUC5AC)on d 11,but no treatment effects were found at d 33.In conclusion,BGase depolymerized high molecular weightβ-glucan in HB in a dose-dependent manner.Hulless barley and BGase did not increase SCFA concentrations(except for 60%HB with 0.1%BGase at d 11)and caused minor effects on digestive tract histomorphological measurements and relative mRNA gene expression.