| Antibiotics have the effect of promoting the growth of livestock and poultry,and have played a positive role in promoting animal husbandry and meat production.However,the long-term sub-dose or over-use of antibiotics has led to a series of negative effects,including drug resistance,reduced immunity of livestock and poultry,frequent bacterial diseases,and residual pollution in livestock products and the environment.All countries around the world have begun to ban the addition of pro-growth antibiotics in the feed and conducted research and exploration of alternative antibiotics.How to maintain or guarantee the growth promoting effect of antibiotics and at the same time solve the negative effect caused by antibiotics is the focus of research.Mannose oligosaccharides and organic selenium have important biological functions in improving intestinal micro-ecology,anti-oxidation,promoting growth and improving body immunity,and are widely used as feed additives in livestock and poultry production.And research on mannose-oligosaccharides as an alternative to antibiotics has been actively explored.However,the experimental studies such as the combining use two of them in livestock and poultry production are rarely reported.In order to reveal the combining application of mannose-oligosaccharides and organic selenium has a synergistic effect on livestock production performance and immune performance regulation,and as a better alternative to antibiotics for livestock and poultry production.In this study,normal broilers and immunosuppressive broilers models were selected.The effects of antibiotic addition,mannose-oligosaccharides and organic selenium single or combining on the growth performance and immune performance of broilers were compared.Further,using broiler immune suppression model in vivo and in vitro to analyze the regulating ability of combining mannose-oligosaccharides and organic selenium on specific immunity,nonspecific immunity and oxidation resistance in broilers.The main results are as follows:(1)Effects of chlortetracycline,mannose-oligosaccharides and organic selenium on performance and slaughter performance of broilers.The experimental animals were divided into 5 groups,and the diet was supplemented with chlortetracycline,mannose-oligosaccharides,organic selenium,mannose-oligosaccharides + organic selenium,and the basal diet group was used as a control.After 42 days of feeding,the results showed that the growth performance of broilers in the chlortetracycline group was significantly improved,mannose-oligosaccharides,organic selenium and mannose-oligosaccharides + organic selenium group can improve the growth performance of broilers,but the difference is not significant especially(P > 0.05).In terms of slaughter performance,the slaughter rate of the chlortetracycline group was significantly lower than that of the mannose-oligosaccharides + organic selenium group,but the abdominal fat rate was significantly increased.The results showed that the addition of mannose-oligosaccharides and organic selenium to the diet can improve the slaughter performance of broilers.(2)Effects of chlortetracycline,mannose-oligosaccharides and organic selenium on immune organs and intestinal villi of broilers.Experimental animals and treatment are the same as experiment(1).The results showed that the thymus gland,bursa and spleen organ index of the mannose-oligosaccharide + organic selenium group at 21 and 42 days displayed an increased tendency compared with the other 4 groups.but there was not a significant difference(P > 0.05);Further using broiler chicken immunosuppressive model validation,in broiler chicken immunosuppression model supplemented with mannose-oligosaccharide+ organic selenium in diet,the immune organs index was significantly higher than that of the CY immunosuppression control group(P < 0.05).Similarly,broiler intestinal villi in the combination of mannose-oligosaccharide+organic selenium was not significantly different in normal chickens,but was significantly increased in the immunosuppressive model(P < 0.05).The results showed that the combination of mannose-oligosaccharide and organic selenium can promote the immune performance of broilers.(3)Regulation of cellular and humoral immunity in broiler by combined addition of mannose-oligosaccharide and organic selenium.Broiler immunosuppressive model and immune cell experiments showed that the combination of mannoseoligosaccharide and organic selenium significantly increased the content of CD4+ and CD8+ T lymphocytes in peripheral blood or in vitro and the ratio of CD4+/CD8+T lymphocytes(P<0.05);In the immunosuppressed broiler model fed with mannose-oligosaccharide and organic selenium for 42 days,the level of cytokines(IFN-γ,IL2,IL4,5,6,10)in blood was significantly increased.The levels of immune proteins such as IgA,IgM,SIgA and ND-Ab antibodies were significantly increased(P<0.05 or P<0.01).The above results revealed that mannose-oligosaccharides and organic selenium can effectively improve the cellular immunity and humoral immunity of broilers.For impacts nonspecific immunity and antioxygenic property of broilers on the combining application of mannose-oligosaccharide and organic selenium,the results showed the combination of mannose-oligosaccharide and organic selenium significantly increased the activity of peripheral blood NK cells and GSH-Px2,and significantly reduced the content of MDA(P < 0.05 or P < 0.01),indicating that the combination of mannose-oligosaccharide and organic selenium could effectively activate the nonspecific immunity of broilers and increase their antioxidant ability.(4)Combining application of mannose-oligosaccharides and organic selenium promote the cooperation of intestinal immunity and spleen specific immunity.Through the co-cultivation of intestinal mucosal cells and spleen lymphocytes of broilers,the relationship between intestinal immunity and spleen-specific immunity was analyzed under the combined stimulation of mannose-oligosaccharides and organic selenium.After co-cultivation of intestinal mucosal cells and spleen lymphocytes,the levels of cytokines in intestinal SIgA and spleen lymphocytes were significantly higher than those in control cells(P < 0.05 or P < 0.01).It is suggested that there is a synergistic relationship in the cooperation of intestinal immunity and spleen specific immunity between mannose-oligosaccharide and organic selenium.In summary,this study used normal,immunosuppressed broiler models and isolated immune cells to compare the combining effects of mannose-oligosaccharide and organic selenium on growth performance and immune performance of broilers with antibiotics(chlortetracycline).It is thought that mannose-oligosaccharide and organic selenium can be used as a feed additive to promote the performance,specific and non-specific immune properties and antioxidant capacity of broilers.It can be used as a substitute for antibiotics in the production of broilers.Further in vitro and in vivo experiments revealed that in combination with mannose-oligosaccharide and organic selenium,intestinal immunity and spleen-specific immunity have a mutually reinforcing synergistic relationship. |
