| Poultry product is an important source of Chinese meat consumption. Over the past 30 years, China consumer’s demand for poultry products was increased rapidly. Being restricted by domestic breeding and feeding technology level, poultry farming suffered from disease, nutritional imbalance, stress and so on, which results the poultry product market volatility sometimes. It became an important subject in our agriculture that how to prove poultry health and meet the demand of residents. Chicken spleen transfer factor (TF) has attracted the attention of more and more people in poultry production. It is a set of small molecular peptides, nucleotides and amino acid composition with no antigenicity, released by T lymphocytes. TF was widely used to enhance the immune preparations in poultry production. Therefore, we divided the 5th-day-old chicken to four groups fed with different dose of TF (0mg、0.1mg、0.25mg and 1mg) in this experiment. When chicken grew to the 40th day old, duodenum, jejunum, ileum and rectum were taken out and gut mucosal histology structure, anti-oxidation ability, immune cytokines, MUC2 and TLR2/4 (Toll-like receptor 2/4, TLR2/4) mRNA expression were studied to verify the mechanism of chicken spleen transfer factor. At the same time, the application of chicken spleen transfer factor in production was studied too. Chicken’s body weight and growth rate of immune organs were observed to explore their growth and intestine mucosal barrier, which provides a certain theoretical support for the application of TF to livestock and poultry production. The results of those studies are as follows:1. The role of TF on the chicken intestine mucosa histological structureThe villus height and the ratio of V/C (villus height to crypt depth, V/C) were significantly enhanced in the small intestine of 1.0 mg-TF-fed chicken (P<0.05). Goblet cell density was significantly increased in 1.0 mg-TF-fed 40th-day-old chicken’s duodenum, jejunum and ileum (P<0.05). Three doses of TF have no effect on goblet cell density in the rectum. These results indicate that the TF improved the mucosal mechanical barrier in the small intestine of chicken.2. The rolet of TF on the secretion of cytokines intestineThe IL-10 level in the duodenum, jejunum, ileum and rectum of 1.0 mg-TF-fed 40-day-old chicken were significantly enhanced (P<0.05), the IL-13 level in 0.25 mg-TF-fed 40-day-old chicken’s jejunum, ileum and rectum were also enhanced significantly (P<0.05).After the treatments with 0.1 mg and 0.25 mg TF, the IL-1 (interleukin-1) content of chicken duodenum was significantly declined at 40-day-old as compared to control group (P<0.05). Treatments with 0.25 mg and 1.0 mg TF declined significantly the content of TNF-α (Tumor necrosis factor-α) in duodenum compared to control group (P<0.05). These results indicated that the TF improved the mucosal immunologic barrier in the chicken intestine by increasing antiinflammatory cytokines and decreasing proinflammatory cytokines.3. The role of TF on the expression of MUC2、TLR2 and TLR4 mRNA in intestineThe intestine’s MUC2 mRNA expression level in 1.0 mg-TF-fed 40-day-old chicken’s duodenum, ileum and rectum were significantly enhanced (P<0.05). Treatments with 0.25 mg and 1.0 mg TF can significantly reduce TLR2 and TLR4 mRNA expressions of duodenum (P<0.05), jejunum (P<0.05), ileum (P<0.01, P<0.05) and rectum (P<0.01) in the 40-day-old chicken. This role showed dose-dependent feature.4. TF’s influence on chicken intestines antioxidant functionTreatment with 0.25 mg TF significantly improved the duodenum, jejunum and rectum CAT (catalase, CAT) activity (P<0.05). The intestinal GSH-Px (glutathione peroxidase, GSH-Px) activity in the 0.25mg-TF-fed 40-day-old chicken’s duodenum, jejunum was significantly increased (P<0.05) which compared with control group. Treatment with 0.25 mg and 1 mg TF can significantly reduce the MDA (Malondialdehyde, MDA) content of duodenum, jejunum and ileum (P<0.05). Treatment with 0.25 mg TF can significantly enhance T-AOC (the total antioxidant capacity, T-AOC) in duodenum, ileum and rectum (P<0.05).5. The effect of TF on the body weight, immune organs and disease resistanceThe body weight of 40-day-old group treated with 1.0 mg TF was significantly higher than control group (P<0.05). Treatment with 0.25 mg TF-fed can significantly increase the weights of spleen and thymus in the 14th day old and 22th day old chickens. Meanwhile, the antibody titer of Newcastle disease vaccine was greatly increased (P<0.001).6. TF application in poultry productionLarge group of test results showed that TF could effectively improve the survival rate and body weight of the chicken population in large-scale production, reduce feed to meat ratio and improve the efficiency of farmers. TF could also significantly improve the disease resistance of chickens; reduce the mortality of Newcastle disease chicken group. As a result, the loss due to the spread of the disease would be greatly reduced.Conclusion:The villus height, the ratio of V/C, the proliferation of intestinal stem cells and the goblet cell density could be significantly increased by TF to improve the mucosal mechanical barrier in the chicken intestine. TF could also significantly promote the expression of anti-inflammatory cytokines and inhibit the level of proinflammatory factor to improve the mucosal immunologic barrier in the chicken intestine, and resulted in to promote the growth, performance and disease resistance of chickens. Its effect mechanism was involved in up-regulation of MUC2 mRNA transcription level, down regulation of TLR2 and TLR4 mRNA transcription and increase of antioxidant function in the chicken intestines by TF. |
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