Effects Of Fermented Feed And Its Fermentation Metabolite Produced By Multiple Probiotics On Intestinal Health Of Chicken

Objectives: Fermented feed produced by probiotic can improve the health status of chicken. This experiment was designed to inquiry the importance of fermentation metabolite in fermented feed, and its mechanism of action on broiler’s intestinal barrier function, providing an theoretical basis for the application of fermentation metabolite.Method : Fermented feed was produced by multiple probiotics and sterilized for fermentation metabolite. The composition changes were analyzed. Four hundred and ninetyfive numbers of 1-d-old broilers were randomly allotted into 5 dietary treatments: positive control was basal diet + 2% unfermented feed(bacitracin zinc 80 mg/kg feed, colistin sulfate 20 mg/kg feed), negative control was basal diet + 2% unfermented feed, 1% fermented feed group was basal diet + 1.0% fermented feed + 1% unfermented feed, 2% fermented feed group was basal diet + 2.0% fermented feed, 2% sterilized fermented feed group was basal diet + 2.0% sterilized fermented feed. The broilers were weighted regularly, and the feces were collected on the first 35 days for determination of nutrient apparent metabolic rate and urease activity. Broilers slaughtered on day 70. The serum was got for endotoxin(LPS), TNF-α, IL-1 and antioxidant indicators. The organ were removed for weighing. The cecal contents were taken for determination of organic acids and urease activity. The jejunum and ileum were removed for observation the intestinal morphology through HE staining and scanning electron microscopy. The mucosa of jejunum and ileum were scraped for determination of antioxidant indicators and concentration of SIgA. The intestinal tight junction proteins, cytokines, mucin(MUC2), β-defensins(AVBD-9) gene expression in ileum mucosa were assayed by RT-PCR.Results:(1) The level of pH, total organic acids, free peptides, nisin Z, amino acids was 4.68、1059.66mmol/kg、5.19%、1.49mg/kg, and sodium phytate and crude fiber was decreased by 60.99%、19.48% after fermentation.(2) Compared with negative control, the fat metabolic rate of other treatments were increased, as well as crude protein metabolic rate of positive control(P<0.05). At 0-3 weeks of age, daily gain of 2% sterilized fermentation feed group increased(P<0.05). At 7-10 and 0-10 weeks of age, daily gain and feed intake of positive control and 2% fermented feed group were significantly increased. The liver index of 2% fermented feed group was decreased by 18.55%, Thymus index of 2% fermented groups were equal to 1% one, and its 46.90%, 28.68%(P<0.05) higher than positive and negative control separately. The bursal index of 2% fermented feed group tended to increase, but positive group tended to be downward(P=0.061).(3) Compared with negative group, the level of serum TNF-α and IL-1 in other groups were significantly decreased; The malondialdehyde(MDA) level in serum and ileum of 2% fermented feed group were decreased, while its and total superoxide dismutase(T-SOD) activity, total antioxidant(T-AOC) and catalase(CAT) activity in jejunum and CAT activity in ileum were increased; Only the CAT activity in jejunum of 1% fermented feed group was increased; The MDA level in serum and ileum of 2% sterilized fermented feed group were decreased, while its T-SOD, CAT activity in jejunum and CAT in ileum were increased and higher than positive control, which CAT activity in serum and jejunum were increased, while MDA levels ileum was decreased(P<0.05); The jejunum and ileum villi morphology of 1% fermented feed and 2% sterilized fermented feed group was better, but not as good as group 2% fermented feed group and positive control; The jejunum microvilli height, ileum villus height and velvet gland ratio of 2% fermented feed group increased, while its ileum microvilli height decreased, all of these datas was similar to datas of positive control and jejunum microvilli height and velvet gland ratio in 2% sterilized fermented feed group. Jejunum microvilli height of fermentation groups increased, but lower than the positive control and sterilized fermented feed group; Urease activity in cecal of 2% fermented feed and positive control group decreased, and urease activity in fecal of fermented and sterilized fermented feed group was significantly lower than the positive and negative control. The total organic acids in all treatments except negative control group increased, and level in the 2% fermented feed group was highest.(4) Compared with positive and negative control, the gene expression levels of TNF-α and IL-6 in ileal mucosa of 1% fermented feed group and 2% sterilized fermented feed group was significantly down-regulated, as well as TNF-α expression levels of 2% fermented feed group; Compared to group negative control, the concentration of SIgA in ileum of 2% fermented feed and sterilized fermented feed group was increased, and gene expression of MUC2 was also upregulated(P<0.05); The gene expression levels of Claudin-1, Claudin-3, Claudin-5, ZO-1, ZO-2, TLR2, TLR4, AVBD-9, IL-18 in ileum of sterilized fermented feed group was significantly up-regulated, while the gene expression level of TLR2, AVBD-9, Claudin-3 and Claudin-5 were lower than 2% fermented feed group but higher than positive control(P<0.05).Conclusion:The nutritional value of fermented feed produced by multiple probiotic was improved; The growth performance and intestinal barrier function of broilers feed with fermented feed were improved, and the fermentation metabolite plays an important role. The TLRs/NF-κB signaling pathway and immunity was activated and gene expression of tight junction proteins, mucin and defensin were up-regulated, while inflammatory cytokines were down-regulated, and thus the intestinal barrier function was improved.