Protective Effect And Preliminary Mechanism Of Vitamin D₃ On Oxidative Stress Induced By Diquat In Wenchang Chickens

The purpose of this paper is to study the relieving effect of adding different doses of vitamin D₃（VD₃）to the basal diet of Wenchang chickens on the oxidative stress induced by intraperitoneal injection of diquat（DQ）in Wenchang chickens.It is mainly reflected in the effects on growth performance,biochemical indicators and antioxidant signaling pathways,and provides a theoretical basis for improving the scientific and rational use of VD₃in feed.In the experiment,480 healthy 1-day-old Wenchang chickens（all female）were selected,pre-fed to 10-day-old,and randomly divided into 6 treatment groups,with80 chickens in each treatment group,10 replicates in each group,and 8 in each replicate.Four treatment groups were injected with 6.5 mg/kg and 8 mg/kg DQ by intraperitoneal injection on the 17th and 38th day respectively to establish the oxidative stress model,and two treatment groups were injected with the same amount of phosphate buffered saline（PBS）.The oxidative stress model was established and the four groups were named as DI group（200μL PBS per day）,1000VD+DI group（1000 IU VD₃/kg per day according to their feed intake）,2000VD+DI group（2000 IU VD₃/kg per day according to their feed intake）and 4000VD+DI groups（4000 IU VD₃/kg per day according to their feed intake）.The other two groups were CK group（given 200μL PBS daily）and 4000VD group（4000IU VD₃/kg per day according to their feed intake）.The experimental period was 28 d.During the experimental period,the animals had free access to food and water.The test results are as follows:1.Oxidative stress will cause a significant decrease in average daily feed intake（ADFI）and Average daily gain（ADG）of Wenchang chickens,an increase in feed-to-weight ratio,a decrease in slaughter performance and a decrease in meat quality（p H value and water retention）.With the increase of the dosage of VD₃,the above-mentioned symptoms were recovered to varying degrees.2.Oxidative stress can significantly reduce the activities of digestive enzymes（including trypsin,α-amylase and lipase）in the jejunum and duodenum of Wenchang chickens.With the increase of VD₃dosage,the digestive enzyme activities of each group showed different degrees of recovery compared with the DI group.3.Oxidative stress could significantly increase the serum levels of diamine oxidase（DAO）,aspartate aminotransferase（AST）,urea nitrogen（BUN）,and total cholesterol（T-CHO）in Wenchang chickens.And the inflammatory factors interleukin-1β（IL-1β）,interleukin-6（IL-6）and tumor necrosis factor-α（TNF-α）were significantly increased.Compared with the DI group,the biochemical indexes and inflammatory factor concentrations in each group were decreased to varying degrees with the increase of VD₃dosage.4.Oxidative stress can damage the intestinal,liver and kidney tissue morphology of Wenchang chickens,increase the level of apoptosis in the jejunum,reduce the level of glycogen secretion,reduce the expression of Zonula occludens protein 1（ZO-1）and Occludin（OCLDN）,and destroy the intestinal barrier function.With the increase of VD₃dosage,the above symptoms were improved to varying degrees.5.Oxidative stress can increase the content of Malondialdehyde（MDA）in the serum,jejunum and liver of Wenchang chicken,decrease the content and activity of antioxidant enzymes and down-regulate the expression of major proteins in the antioxidant stress signaling pathway.With the increase of VD₃dosage,the antioxidant capacity of Wenchang chicken gradually recovered and there was no significant difference in oxidation-related indexes between the 4000VD+DI group and the CK group.