عنوان مقاله [English]
Introduction Heat stress is one of the environmental stresses in summer. It was showed that decrease digestibility nutrient and impair the function of immune and antioxidant system. Several methods have been suggested to reduce the negative effects of heat stress in broiler chickens including: supplemented antibiotic, probiotic and prebiotic in the various levels of diets. However, extensive usage of antibiotics will cause the increasing resistance of pathogens to antibiotics and the accumulation of antibiotics remain in animal products and the environment. It is becoming increasingly evident that to achieve the aims above and to reduce the use of antibiotics significantly, it is necessary to combine of intervention strategies such as genetic selection of resistant animals, elimination of pathogens from feed and water, vaccinations, and applications of suitable feed and water additives. On the other hand, it was showed that probiotic and prebiotic additives improve the function of immune and antioxidant system. However, to our knowledge, information is lacking on the effects of simultaneous using probiotic and prebiotic on broiler antioxidant and immune system. This experiment was conducted to compare the effect of different levels of probiotic and prebiotic on antioxidant system, immune system, liver enzymes activity and some blood parameters under heat stress in broilers chickens.
Material and Methods Two hundred and fifty six broiler chickens (Ross 308) were used in a completely randomized design with a 4×2 factorial arrangement of treatments and four replicates with 8 chickens in each. Broiler chickens were fed with 2 levels of probiotic (0 and 0.01) % and 4 levels of prebiotic compound (0, 0.025, 0.050 and 0.075) % diet during 29- 42 days of age. Blood sample was collected in order to measure the serum concentration of metabolites (glucose, total protein, globulin and albumin), minerals (Fe, Mg, Ca and P), liver enzymes activity (ALP, ALT, AST), antioxidant system (SOD, GSH-px) and immune system (IgG, IgM). Data from the experiment were analyzed by mixed model procedure of SAS. Cage was the experimental unit. We considered P < 0.05 to be statistically significant. Differences among means were tested by the Tukey method.
Results and Discussion During the past decade, some studies have supported the potential health benefits of probiotics, such as improved gastrointestinal microbiota ecosystems, stimulation of the immunological system, anticarcinogenic activities, and reduced oxidative stress. The results of present study indicated that supplemented probiotic in diet was significantly increased the serum concentration of glucose, magnesium and IgG and decreased globulin. The results of several other studies similarly confirmed that treatment of animals with probiotics increase the serum concentration of glucose and reduce or no effect on the serum concentration of albumin, globulin and total protein in broiler chickens. The results this study also showed that treatment of animals with the different levels of prebiotic was caused insignificant change in the serum concentration of metabolites and minerals. Of course, simultaneous using of 0.01% probiotic and prebiotic in the levels of 0.05% and 0.075 % diet was caused to increase of serum glucose significantly. Adding probiotics and prebiotics and their interactions in the diet has insignificant effect on the enzyme activity of serum ALT and ALP broiler chickens under heat stress. Few studies were conducted as to the interaction effect of probiotics and prebiotics on immune and antioxidant system. The results of this experiment showed that addition of 0.01% probiotic and prebiotic in the level of 0.05 % to diet was caused significant increase the enzyme activity of GSH-px. Furthermore, treatment of 0.01% probiotic and prebiotic in the level of 0.075% to diet was caused significant increase the antibodies production against SRBC. The results of previous studies have been showed that the function of immune and antioxidant system impair under heat stress. On the other hand, in agreement with present results, it was indicated that probiotics and prebiotics increase GSH-px and IgG and the antibodies production against SRBC. Thus, both the present experiment and the other reports indicate that dietary supplementation of probiotic and prebiotic improve the immune and antioxidant system of broilers and could be as an alternative to antibiotics
Conclusion In general, by the results of present study, it can be concluded that supplemented probiotic invidually in diet significantly increase the serum concentration of glucose, magnesium and IgG and decreased globulin. Furthermore, using of 0.01% probiotic and 0.05% and/or 0.075% prebiotic in diet indicated that probiotic and synbiotic, can improve the blood parameters, antioxidant system and immune system in broiler chickens under the heat stress.