| Plant polysaccharides is an important natural active ingredients extracted from plants, a lot of results showed that plant polysaccharides enhanced immune function and increased the antioxidant capacity were the main mechanism to play a medicinal. Therefore, the plant active polysaccharides are promising green feed additives that is able to substitute antibiotics. This experiment selected Astragalus polysaccharide as the object of study, took the broiler chickens as experimental animals, through two trials and the establishment of oxidative stress model, the aim of our experiment was to study the effect and regulation mechanism of Astragalus polysaccharide (APS) on growth performance, intestinal development, structure and function of broilers.Experiment1This experiment was conducted to study the effect of APS on growth performance, viscera index, pancreas digestive enzymes activity, antioxidant capacity and mucosal structure in small intestine of Broilers. Two hundred and fifty-six healthy1-day-old avian broilers were randomly assigned to four dietary treatments with eight replicates per treatment and eight broilers per replicate. The broilers were fed the basal diet supplemented with0,0.2%,0.4%and0.6%APS, respectively. At7th days and14th days, three chickens were selected from each replicate to be slaughtered in order to measure their indicators. The results showed that there were no effect of APS on growth performance (p>0.05), there were significant effect on viscera index, APS increased liver index and pancreas index significantly (p<0.05) in7-day-old broilers, but had no effects in14-day-old broilers, adding APS to diet could increase pancreatic lipase and trypsin activity both in7-day-old and14-day-old broilers significantly, but had no effect on pancreatic amylase, adding APS to the diets could increase serum and liver antioxidant enzyme activities and decrease MDA content in7-and14-day-old broilers, there were significantly differences in the morphological change of mucosa of small intestine, the treatments were better in the morphology than that of control, meanwhile, the heights and widens of villus, thickness of mucosa, V/C value and villus surface area in treatment groups were larger than that of control and also the effects of APS on morphology development in small intestine were more effective in the7-day-old Broilers than that of14-day-old Broilers. These results indicate that APS could improve organ development, and could increase pancreatic lipase activity both in7-day-old and14-day-old broilers significantly (p<0.05), and increase the activities of antioxidant enzymes in serum and liver to strengthen immunity and antioxidant capacity of broilers, improved the heights and widens of villus, thickness of mucosa, V/C value and villus surface area, and the treatment with adding0.6%APS was the most effective group, but there are no effects on the growth performance of broilers aged1to14days.Experiment2In this experiment, to study the effect of APS on growth performance, blood and liver antioxidant status and small intestine morphology of oxidative stress model broiler chickens, two hundred and fifty-six healthy1-day-old Avian broilers were randomly assigned to four dietary treatments with eight replicates per treatment and eight broilers per replicate, respectively as group A、B、C and D. After7days prepare experiment, each group except group A was added20mg/L hydrocortisone in their drinking water, for5days of continuous drinking, and group A drunk distilled water instead, at the same time, group C and group D were fed the basal diet supplemented with0.4%and0.8%APS until the21th day. At7th days and14th days, three chickens were selected from each replicate to be slaughtered in order to measure their indicators. The results showed that average daily feed intake and average daily gain and feed to gain ratio of adding APS group were significantly higher than that in the control group and model group, drinking hydrocortisone water and adding APS to the feed had no effect on viscera index, the model group serum and liver antioxidant enzyme activity was significantly lower than the control group(p<0.05), adding APS to the diets could increase serum and liver antioxidant enzyme activities and decrease MDA content significantly(p<0.05), the heights and widens of villus, thickness of mucosa, V/C value and villus surface area in model groups were smaller than that of control, and adding APS group was significantly larger than model group(p<0.05). In conclusion, after drinking hydrocortisone water the growth performance of model group were significantly lower compared with the control group, and it could significantly improve growth performance by adding the APS, it indicated that the APS had a therapeutic effect to the growth performance of broilers under oxidative stress conditions, drinking hydrocortisone water and adding APS to the feed had no effect on viscera index, Liver and serum SOD and GSH-Px activity could be reduced and the content of MDA could be improved by drinking the water of hydrocortisone resulting in oxidative stress, APS could enhanced the body’s antioxidant capacity by increasing antioxidant enzyme activities and decreased MDA content in serum and liver of broiler, drinking hydrocortisone water could result in the oxidative damage in small intestine mucosa of broilers, reduce the height and width of the intestinal villi, mucosal thickness, V/C value and villus surface area, and adding APS could improve it significantly, and adding0.4%of the low-dose group effect is more prominent, this showed that APS had a therapeutic effect against oxidative stress. |
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