Effects Of Dietary Xylooligosaccharides On The Performance,Immune Function And Intestinal Health Of Laying Hens

A single factor experiment was designed to determine the effects of dietary supplementation with xylooligosaccharides(XOS)on performance,immune function and intestinal microbiota of laying hens.A total of 1080 Lohmann laying hens(28 weeks of age)were randomly distributed to six treatment diets that included XOS at concentrations of 0.01%,0.02%,0.03%,0.04%or 0.05%.Each treatment consisted of 6 replicates of 30 hens each.The experiment lasted 8 wk.The result showed:1)XOS had no significant effect on the performance of laying hens.In the fourth week of the experiment,the relative weight of the eggshell at 0.02%,0.03%,0.04%and 0.05%XOS groups was significantly higher than that of the control(P<0.05).In the eighth week experiment,eggshell thickness at 0.03%,0.04%and 0.05%XOS groups was significantly higher than that of the control(P<0.05),relative eggshell weight at 0.04%and 0.05%XOS groups was significantly higher than that of the control group and 0.01%,0.02%XOS groups(P<0.05),the addition of dietary XOS to the laying hens resulted in a linear increase(P<0.05)in eggshell thickness and eggshell relative weight.2)XOS supplementation significantly increased the apparent digestibility of the calcium(P<0.05),the addition of dietary XOS to the laying hens resulted in a linear increase(P<0.05)in the apparent digestibility of calcium,and it was higher in 0.04%XOS group than the control.XOS had no significant effect on the apparent digestibility of crude protein,crude fat,dry matter,phosphorus and energy.3)XOS significantly increased the villus height(P<0.05)and the villus to crypt(VH:CD)ratio(P<0.05).The villus height of jejunum at 0.01%,0.02%,0.04%,and 0.05%XOS groups was significantly higher than that of the control,the VH:CD ratio of the jejunum at 0.03%,0.04%and 0.05%XOS groups was significantly higher than that of the control.In addition,with the increase of the XOS concentration,the villus height and the VH:CD ratio increased linearly.4)XOS significantly increased the content of plasma 1,25(OH)2D3(P<0.05)and significantly reduced the content of plasma cholesterol and very low-density lipoprotein(VLDL)(P<0.05),the addition of XOS at 0.03%to the basal diet increased plasma 1,25(OH)2D3 levels compared to the control,plasma cholesterol levels at 0.02%,0.03%,0.04%and 0.05%XOS groups was significantly lower than that of the control,the plasma VLDL levels in the XOS groups were significantly lower than that in the control,with the increase of XOS concentration,plasma cholesterol and VLDL decreased linearly.5)The levels of Immunoglobulin M(IgM),interleukin 2(IL-2)and tumor necrosis factor alpha(TNF-a)were significantly increased in plasma(P<0.05),the addition of XOS at 0.03%XOS to the basal diet increased the content of plasma IgM compared to the control,the addition of XOS at 0.02%and 0.03%XOS to the basal diet increased the content of plasma IL-2 compared to the control,the content of TNF-a at 0.02%,0.03%,0.04%,and 0.05%XOS groups was significantly higher than that of the control.6)XOS significantly improved the content of bifidobacterium in the cecum,and the content of the bifidobacterium at 0.03%,0.04%and 0.05%XOS groups was significantly higher than that of the control(P<0.05).With the increase of the XOS concentration,the content of bifidobacteria was increased linearly.In addition,XOS significantly increased the content of butyric acid,propionic acid and acetic acid in the cecum(P<0.05).the addition of XOS at 0.03%,0.04%and0.05%XOS to the basal diet increased the content of acetic acid compared to the control,the addition of XOS at 0.03%and 0.05%XOS to the basal diet increased the content of propionic acid compared to the control,the addition of XOS at 0.03%and 0.04%XOS to the basal diet increased the content of butyric acid compared to the control,With the increase of the concentration of XOS,the content of acetic acid and butyric acid increased linearly.In summary,XOS can improve the intestinal morphology,increase the absorption of calcium,improve the quality of egg shell,enhance the immune function of the body,promote the growth of bifidobacterium and produce short chain fatty acids in laying hens.Therefore,XOS can be concluded to be an effective feed additive,The optimum dosage in laying hens diets is 0.03%-0.04%.