| Our preliminary studies showed the strain of Pediococcus pentosaceus (CGMCC No.6566) which was screened from the cecum of a healthy 154-day-old Caoke chicken in the free-range system had improved the growth performance and breast flavor characteristics of 76-day-old Qingjiaoma chickens. In the present study, we improved the production techniques to prolong the storage life of P. pendicoccus microcapsules, and focused on its potential effect on the growth and disease-resistance performances of AA broiler chickens. We chose a Salmonella enteritidis strain which is seriously harmful to commercial poultry industries, and researched on the potential capacity of P. pentosaceus for S. enteritidis infection.In the current study, AA broilers was adopted as the experimental materials. the P. pentosaceus microcapsule was added in the basal diet. We monitored the growth and eliminating ratio every day, and recorded the body weight of each bird once per week. Besides, we monitored the body temperature, the living count of S. enteritides and Escherichia coli in the ceca of all individuals and their death rates as well as the mRNA expression of eight key genes in TLR4 signaling pathway in the cecum and spleen at different time points. The results were as follows:1.The optimal embedding conditions were 2% Sodium alginate,1% Calcium Chloride,5% skim milk powder,6% lactose powder, and P. pentosaceus microcapsules with an embedding ratio of 80.44% were obtained. After the optimal embedding treatment, it can prolong the storage life of probiotic products in the room temperature, as well as the total living count of P. pentosaceus can stay relatively steady to the gut and continue to function.2. Chickens in the treatment group had the significant rate of weight to gain (W/G= 13.36%), breast muscle rate (19.24%) and thigh muscle rate (12.26%) as compared with those in the control group. Besides, birds that were supplemented with P. pentosaceus had 6.07% higher feed conversion ratio than chickens in the control group. There were no significant differences in thymus, spleen and bursa of Fabricius index between the trial group and the control group. Chickens in the treatment group showed an increase of three SCFAs contents in the cecum (acetic acid, propionic acid, butyrate) compared to those in the control group, especially in the butyrate concentration (P< 0.05). Our results indicated that the P. pentosaceus microcapsule products indeed have a probiotic effect on the growth performance and meat production, as well as immune function and GI environment of broiler chickens.3. S. enteritides infection affected body temperature and death number of broiler chickens, and the death time concentrated at 3 to 7 days post challenge. Pedicoccus pentosaceus treatment indeed reduced the death rates (33.33%) compared to that in the control group. The number of Salmonella enteritidis in chicken’s cecum increased rapidly after infection in the control group but little changed in the trial group, and a significant difference was present between the two feeding groups (P< 0.05). This study showed that P. pentosaceus microcapsule product has a probiotic effect on S. enteritidis infection. It successfully reduced the colonization of pathogenic bacteria in the GI tract of AA broiler chickens.4. Chickens in the control group had the highest expression of TLR4, MyD8, TRAF6, NF-κB, IFN-β, TNF-α and IL6 on the first day of infection, the mRNA expression of 7 genes were significant higher than that of the trial group, and the expression gradually decreased with the increase of day age, the expression rule of 7 genes in spleen was the same as cecum; but the expression rule of 7 genes in the trial group was different from the control group. Chickens had the highest expression at 3 and 7 day post-challenge. The expression of each gene was lower than the control group. This study showed that P. pentosaceus microcapsule product has a probiotic effect on S. enteritidis infection. It successfully reduced the colonization of pathogenic bacteria in the GI tract of AA broiler chickens by regulating of TLR4 signaling pathway. |
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