Effects Of Synbiotics On Production Performance,Antioxidant Capacity,Immune Property And Intestinal Barrier Function Of Cherry Valley Ducks

Synbiotic,a new type of microecological preparation,has many advantages such as green health,no drug resistance and no toxic side effects,and is an ideal antibiotic substitute.The present study was set out to investigate the effects of dietary supplementation of synbiotics,as a possible antibiotic substitute,on production performance,antioxidant capacity,immunity and intestinal barrier function of Cherry Valley ducks.Briefly,a total of 540 Cherry Valley ducks(one-day-old)were randomly categorized into 3 groups: control group(basal diets free from the antibiotic),antibiotic group(basal diets supplemented with 40 mg/kg bacitracin zinc),and synbiotic group(basal diets supplemented with 1 000 mg/kg synbiotic).Each group consisted of 6 replicates of 30 ducks each.The experimental period lasted for 42 days,and divided into starter period(1-14 d)and grower period(15-42 d).At day 14 and 42 of the experiment,one male duck whose weight was close to the average body weight from each replicate was randomly selected and weighed,slaughtered,sampled for determination of the corresponding indicators.The experiment included the following three parts:Experiment 1: Effects of synbiotics on production performance of Cherry Valley ducks.This study was conducted to investigate the effects of synbiotics on growth performance,slaughter performance,muscle quality and serum biochemical indices of Cherry Valley ducks.The results indicated that dietary supplementation of synbiotics significantly increased body weight at day 14 and 42 as well as average daily gain(ADG)during the starter,grower and whole periods(P<0.05),and ADFI during the grower and whole periods(P<0.05).Compared with the control group,dietary antibiotic increased body weight at 14 day and ADG during the starter period(P<0.05).Moreover,ADFI during the grower and whole periods in antibiotic group were significantly lower than that in the control and synbiotic groups(P<0.05),and F/G during the whole period was significantly higher than that in the control group(P<0.05)but no significant difference with that in the synbiotic group(P>0.05).Compared with control group,dietary synbiotic or antibiotic significantly reduced cooking loss of breast and thigh muscle as well as brightness value of thigh muscle(P<0.05),and significantly increased redness value of thigh muscle(P<0.05).There was no significant difference in slaughter performance and serum biochemical indices among three groups(P>0.05).Experiment 2: Effects of synbiotics on intestinal morphology,antioxidant capacity and immune property of Cherry Valley ducks.This study was set out to assess the effects of synbiotics on intestinal morphology,antioxidant capacity and immunity of Cherry Valley ducks.The results indicated that at 14 d in the experiment,duodenal villi height(VH)in the synbiotic group was significantly higher than that in the control and antibiotic groups(P<0.05),and duodenal villi height/crypt depth ratio(V/C)in the antibiotic and synbiotic groups was significantly higher than that in the control group(P<0.05);the ileal VH in the antibiotic group was significantly lower than that in the other two groups(P<0.05).At 42 d,the ileal crypt depth in the synbiotic group was significantly lower than that in the control group(P<0.05),but it was not significantly different compared with the antibiotic group(P>0.05),and ileal V/C ratio in the synbiotic and antibiotic groups was significantly higher than that in the control group(P<0.05).Dietary antibiotic significantly increased the spleen index of 42-day-old Cherry Valley ducks(P<0.05).Dietary synbiotics significantly increased the activity of glutathione peroxidase(GSH-Px)in the serum of 14-day-old Cherry Valley ducks(P<0.05).Ileal mucosal GSH-Px activity at 14 d in the antibiotic group was significantly higher than those in the other two groups(P<0.05).Meanwhile,jejunal mucosal malondialdehyde(MDA)contents at 14 d in synbiotic group was significantly lower than that in the control group(P<0.05)but no differences compared with antibiotic group(P>0.05).The jejunal mucosal superoxide dismutase(SOD)activity of 42-day-old ducks in the synbiotic group was the highest among three groups,and it was significantly higher than that in the control group(P<0.05);Jejunal mucosal GSH-Px activity in the antibiotic and synbiotic groups were significantly higher than that in the control group(P<0.05).The relative m RNA expression of jejunal mucosal Toll-like receptor 3(TLR3),ileal mucosal retinoic-acid-inducible gene-1(RIG-1)at 14 d and ileal mucosal interferon-α(IFN-α)at 42 d in the synbiotic group were significantly higher than those in the control group(P<0.05);Compared with control group,dietary antibiotic or synbiotic increased m RNA expression of jejunal mucosal interleukin-1β(IL-1β)and ileal mucosal TLR3,TLR7 and IL-1β of 14-day-old Cherry Valley ducks(P<0.05).Experiment 3: Effects of synbiotics on intestinal barrier function and cecal microorganisms in Cherry Valley ducks.This study was carried out to evaluate the effects of indices of intestinal barrier function and cecal microorganisms and volatile fatty acids(VFAs)contents.The results indicated that dietary synbiotics significantly increased the number of duodenal,jejunal and ileal intraepithelial lymphocyte(IEL)and goblet cells(P<0.05),and dietary supplementation of antibiotic significantly increased the number of ileal IEL and goblet cells(P<0.05),as compared with the control group;The number of jejunal goblet cells and duodenal,jejunal,ileal IELs in the synbiotic group significantly increased as compared with the antibiotic group(P<0.05);And ileal goblet cell numbers were significant different among three groups(P<0.05).Additionally,dietary synbiotics or antibiotics significantly increased s Ig A contents in the duodenal and jejunal mucosa(P<0.05).The m RNA expression of duodenal mucosal zonula occludens-1(ZO-1)and claudin-1(CLDN-1)in the antibiotic group was significantly higher than those in the control group(P<0.05),but there were no significant differences with the synbiotic group(P>0.05);Dietary synbiotics increased the m RNA expression of jejunal mucosal occluding(OCLN)as compared with the control and antibiotic groups(P<0.05).In addition,dietary synbiotic or antibiotic increased the population of Bifidobacterium in cecal chyme(P<0.05).Dietary supplementation of synbiotics or antibiotics had no significant effects on serum Dlactate,lipopolysaccharide contents and diamine oxidase activity as well as VFAs contents in the cecal chyme of 42-day-old Cherry Valley ducks(P>0.05).The above results indicated that dietary supplementation of 1 000 mg/kg this synbiotic could be used as an antibiotic(40 mg/kg Zinc bacitracin)substitute to improve growth performance and muscle quality,stimulate antioxidant capacity and immunity,enhance the intestinal physical and immune barrier function,increase the population of Bifidobacterium,and regulate the intestinal health of Cherry Valley ducks.