| The negative effects of heat stress(Heat stress,HS)on livestock and poultry and the losses caused by heat stress on the breeding industry are very serious.The harm caused by heat stress to livestock and poultry is still an important problem facing the breeding industry today.Therefore,it is urgent to develop more safe and efficient anti-heat stress additives.As an important component of bile,bile acid(Bile acids,BAs)plays an important role in improving the production performance of livestock and poultry,alleviating stress injury and ensuring the health of livestock and poultry.At present,porcine bile acid is widely used and has obvious therapeutic effect on heat stress,but it is not clear whether it has the same effect on sheep bile acid which is different from porcine bile acid and has different composition content.In this study,porcine bile acid and sheep bile acid were extracted from pig bile and sheep bile respectively.By establishing heat stress models in chickens,molecular biology experiments and serological experiments were used to compare the anti-heat stress effects of porcine bile acid and sheep bile acid in diet.The purpose of this study is to provide experimental and theoretical basis for the development of a new feed nutrition and health additive for improving poultry production performance and preventing heat stress in livestock and poultry.The main contents and results are as follows:In this experiment,21-day-old Highland brown chicks were randomly divided into 4groups: Mock group,HS group,HS-porcine BAs group and HS-sheep BAs group.Mock group and HS group were fed with basal diet,HS-porcine BAs group was fed with basal diet + 400mg/kg pig bile acid,and HS-sheep BAs group was fed with basic diet + 400 mg/kg sheep bile acid once a day for 7 days.Five chickens in each group were randomly selected and weighed at the four time points of 21 d,23 d,25 d and 27 d,and the feed intake was measured at a fixed time every day.At the age of 28 days,the control group was kept at normal temperature,and the other groups were placed in a biochemical incubator with a temperature of 38 ± 0.5 ℃,relative humidity of 60%,and stress for 2 hours.Biochemical experiments were used to detect the activity of serum enzymes and antioxidant capacity in serum and tissue,including the activity of serum biochemical indexes BUN,LDH,AST,ALT and the content / activity of oxidation indexes MDA,SOD and GSH.The m RNA expression of HSP60,HSP70 and HSP90,inflammatory factors IL-1β,TNF-α and IL-10,tight junction protein(Occludin,ZO-1)in liver and jejunum were detected by q PCR method.The ELISA method was used to detect the changes of jejunal immune index SIg A.The changes of intestinal microflora in chickens were analyzed by 16 S r RNA high-throughput sequencing.The results showed that under heat stress,the contents of LDH and ALT in serum increased,the levels of antioxidation in serum,liver and jejunum decreased,the m RNA expression of Heat shock proteins and inflammatory factors in jejunum increased,the structure of jejunum and the content of SIg A in intestine were changed,the relative abundance of Firmicutes decreased and the relative abundance of Bacteroidota increased in intestine.The addition of two kinds of BAs to the diet could increase the average daily gain and the feed conversion rate.Under heat stress,it could improve the antioxidant ability of chickens,reduce the expression of Heat shock proteins and inflammatory factor m RNA in liver and jejunum,and improve the structure of jejunum,mucosal barrier and enrich intestinal microflora.In comparison,the effect of sheep bile acid is more significant.To sum up,the effect of sheep bile acid in relieving heat stress injury in chickens is better than that in pigs,suggesting that sheep bile acid as a new feed nutrition and health additive has great potential to improve poultry production performance and prevent heat stress in poultry. |
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