Effect Of Coated Sodium Butyrate On Intestinal Physiology And Immune Function In Meat Duck

Coated sodium butyrate (CSB), as a new feed additive, can improve the performance of animal production, maintain the intestinal barrier, improve the intestinal morphology, balance the gut community and has a broad prospect in animal husbandry. This study is designed to research the effect of CSB on production performance, blood biochemical indicator, immune response and intestinal mucosal morphology, caecal microorganisms, digestive enzyme activities in Beijing duck. Based on the result of experiments mentioned above, mechanism of the CSB will be discussed and the appropriate additive amount will be determined in duck feed, which would provide a theoretical basis and guidance for the use of CSB as duck feed additive.Two hundred and forty one-day-old Beijing ducks were randomly divided into four groups with four replicates, and every replicate has fifteen duck. The dietary treatments were as follows:basal diet (control), basal+500mg/kg CSB (group Ⅰ), basal+1000mg/kg CSB (group Ⅱ) and basal+40mg/kg zinc bacitracin (group Ⅲ). The experiment lasted for42days. Record the Feed intake during the test everyday and fasting weights were recorded weekly. On the day21and day42, samples were taken from two ducks of each replicate for lab analysis. The results are as follows:Experiment one: Compared with the control group, different degrees of higher body weight gain, average daily feed intake (ADFI) and average daily gain (ADG) in each experimental group were observed during the whole test period. The ADG of adding500mg/kg group was higher than that of the group of adding1000mg/kg group with no significant difference (P>0.05). Adding CSB have increased the duck’s feed conversion rate of day1～21and day22～42with no significant difference among the groups (P>0.05). CSB addition had a tendency to increase the slaughter rate, semi-eviscerated rate, eviscerated rate, the rate of breast muscle, the rate of leg muscle and abdominal fat percentage, although no significant difference was observed between the control group and the test group.Experiment two:On21d, there were no significant difference on total protein, blood urea nitrogen, triglyceride, malondialdehyde and glutamate pyruvate transaminase among the groups (P>0.05). Group Ⅰ was significantly higher than control group on the albumin content in serum (P<0.05) on21d and42d. On42d, significant increase of the content of serum total protein was observed in group Ⅱ (P＜0.05). IgG levels in each test group were higher than that in control with significant difference in group Ⅰ(P<0.01). Adding CSB increased the leave of IgM, and the IgM levels increased correlate with the amount of CSB added,. There was a trend of increasing sCD4content in each group compared with the control group, the sCD4level of21-day-old ducks with diet supplemented with1000mg/kg CBS significantly increased (P<0.05). Serum sCD8level in500mg/kg group was significantly higher than the control group and antibiotic group (P＜0.05). There was no obvious difference in spleen index and thymus index of the group in the whole test period (P>0.05). The diets supplemented with500mg/kg CSB increased the relative weight of bursa of21-day-old ducks significantly (P<0.05).Experiment three:With the addition of coated sodium butyrate increased, there was an trend of increasing duodenal amylase activity on21d. And the trypsin activity in group Ⅱ were significantly higher than that in antibiotic group (P<0.05). The highest trypsin activity on42d was observed in group Ⅰ, but no significant difference among groups (P>0.05). The effect of CSB on lipase activity was more obvious. Compared with the control and antibiotic groups, the lipase activity in group Ⅰ increased obviously on21d and42d (P＜0.05), and group Ⅰ increased obviously on21d (P＜0.05). No significant difference was observed between the groups about D-lactic acid content in plasma (P>0.05), but the level in test groups was lower. Diamine oxidase activity in each test groups was lower than that in the control, and significantly in group Ⅰ and Ⅱ (P＜0.05). The effect of adding CSB in duck feed on duodenal villous length and crypt depth was obvious. The V/C ratio of diet supplemented with1000mg/kg CBS was significantly different (P＜0.01). And there was a obvious increase of V/C ratio in group Ⅰ and Ⅱ on42d (P＜0.05). The jejunum villous length and V/C ratio increased and the crypt depth reduced on42d when supplemented with CBS. On21d, CSB could increase the ileum villus height, decrease crypt depth and significantly increase the V/C values (P＜0.05). No significant difference of V/C value on42d was observed beween CSB adding group and the control group (P>0.05), but significantly higher in CSB adding group than that in the antibiotic group (P＜0.05). Adding1000mg/kg CSB effectively reduced the number of E. coli and Salmonella in cecal on21d and increased the number of Lactobacillus on42d (P＜0.05).The result shows that adding coated sodium butyrate in duck diet could improve digestive function and the intestinal mucosal morphology, and enhance immune function. The effect of coated sodium butyrate was better than zinc bacitracin when used as feed additive. A suitable dose of CSB additive is500mg/kg.