Effect Of EGCG On Fat Deposition In Broilers Under Heat Stress And Its Mechanism

Heat stress is one of the most important external factors that affect the growth of broilers.Heat stress not only reduced feed intake and feed conversion rate,but also affected muscle quality,resulting in pale muscle,soft texture and inelastic texture.It also resulted in oxidative stress in broilers and increased mortality in broilers.In order to reduce the damage caused by heat stress to chicken industry as soon as possible,researchers in related industries have abandoned time-consuming and laborious breeding methods.Therefore,it has become a new research hotspot to solve the problem of heat stress in broilers by nutritional regulation.EGCG has a high biological value,and related experiments have proved that EGCG is effective in improving animal stress.The purpose of experiment 1 was to study the effects of EGCG on growth performance,blood biochemical indexes and liver fat metabolism in broilers under heat stress.Two hundred and twenty-two 14-day-old AA broilers were randomly divided into 4 groups with 6 replicas in each group and 8 chickens in each group.Control group(28 ?,TN group),circulation hyperthermia group(28 ? ~ 35 ?,HS group)were selected as control group.EGCG 0mg/kg(HS0 group),300mg/kg(HS300 group)and 600mg/kg(HS600 group)were added to the diet of high temperature group.The results showed that:(1)Heat stress decreased significantly in broilers.EGCG can effectively relieve the negative effects of heat stress,increase the weight and feed intake of broilers,and increase the antioxidant enzymes(GSH-PX,SOD,)in the body.The activity of CAT(P < 0.05).(2)was better than that of adding 300mg/kg.(3)Heat stress increased fat deposition.Addition of EGCG 600mg/kg could effectively improve the accumulation of fat in chest and leg muscle induced by heat stress(P < 0.05),but had little effect on abdominal fat deposition(P > 0).05).(4)the expression of Nrf 2 gene mRNA in broiler liver increased linearly with the addition of EGCG,but the expression of NF-kappa B and LITAF,Fas,SREBP1 gene mRNA in liver decreased linearly(P < 0.05).The purpose of experiment 2 was to study the effects of EGCG and AMPK on the metabolism of fat cells under the conditions of heat stress.The cells were subjected to packet treatment by in vitro adipocytes,the first group: TN(37.5 ?),TN(37.5 ?)+ EGCG,HS(41.5 ?),HS(41.5 ?)+ EGCG,second group: HS(41.5 ?),HS(41.5 ?)+ EGCG,HS(41.5 ?)+ EGCG + Compound C(AMPK inhibitor).The results showed that(1)EGCG could improve NF-?B,LI in heat stress.MRNA expression of TAF,FAS,SREBP1 gene decreased mRNA expression of Nrf 2 gene(P < 0.05).However,EGCG had no effect on the expression of these genes at normal temperature(P > 0.05).(2).In heat stress environment,AMPK inhibitor had antagonistic effect on EGCG,and it could counteract the regulation of EGCG on heat stress(P < 0.05).The reverse confirmed that AMPK may have a function similar to that of EGCG.