Effects Of Chronic Heat Exposure On Fat Deposition And Fat Metabolism In Male And Female Beijing-You Chickens

The current study was conducted to investigate effects of chronic heat exposure on growth performance, meat quality, and fat deposition in Beijing-You (BJY) chickens. The mechanism underlying these changes in response to heat stress was also studied,and provided basic data for breeding anti-heat stress breeds.One hundred and forty-four 49-d-old healthy BJY chickens (72 males and 72 females) with similar weigh (male: 608.58±13.07g; female: 518.50±8.33g) were randomly assigned to two treatments with 6 replicates in each treatment and 6 birds in each replicate: high-temperature group, 35±0.37℃; optimal-temperature group, 25±0.38℃. The experiment lasted for 23 days. Fat deposition, circulating lipid flux, concentration of adipocytokines,enzyme activities and expression of related genes were at 12 and 23 d were assayed.The result showed as followed:1,Effects of chronic heat exposure on growth performance, carcass traits, and meat quality in male and female Beijing-You chickens.1) During 1-11d, male and female weight gain was decreased (P <0.01), but feed: weight gain of them was not affected by heat exposure (P>0.05). During 12-22d, heat exposure depressed male but not female weight gain (P<0.01), and increased feed:wight gain of males (P<0.01); 2) For males, carcass and leg weight proportion were not affected at 12 d (P>0.05), but were increased by heat exposure at 23 d (P<0.05). For females, leg weight proportion were decreased at 12 d (P<0.05), but were not affected by heat exposure at 23 d (P>0.05); 3) pH, drip loss, MDA, and protein carbonyl in breast muscles of males and females were not affected by heat treatment (P>0.05).2,Effects of chronic heat exposure on fat deposition and fat metabolism in male and female Beijing-You chickens. 1) For males, abdominal, intramuscular, and subcutaneous fat deposition proportion were not affected at 12 d(P>0.05), but was decreased by heat exposure at 23 d(P<0.01). For females, abdominal and intramuscular fat deposition proportion were decreased by heat exposure at 12 d(P<0.05), subcutaneous fat deposition were decreased (P<0.05), and abdominal and intramuscular fat deposition proportion were not affected by heat exposure at 23 d (P>0.05); 2) For males, The concentration of insulin(INS) in plasma was increased (P < 0.01), triglyceride (TG) concentration was decreased by heat exposure at 12 d(P<0.01). INS and TG concentration in plasma were decreased (P<0.01), glucose (G) concentration was increased by heat exposure at 23 d(P< 0.01). For females, Free fatty acids (FFA), and TG concentration was decreased(P<0.01), very low densitylipoproteins(VLDL) concentration was decreased at 12 d (P=0.07),G concentration was decreased (P<0.01), VLDL was increased(P=0.065), TG and FFA concentration were not affected by heat exposure at 23 d(P>0.05); 3)The activities of lipoprotein(LPL) in intramuscular fat of male and female was significantly decreased at 12 d (P<0.05). At 23 d, heat exposure decreased activities of LPL in intramuscular fat in male but not female (P<0.05); 4)The blood level of adiponectin(ADP), resistance(RES) in male and female were not affected (P>0.05); The blood level of leptin in males was markedly decreased(P<0.01), but in femals was increased by heat exposure at 12 d(P<0.05); 5)Expression of LPL in femals was decreased at 12 d (P<0.05), but was increased by heat exposure at 23 d(P<0.01). Expression of very low density lipoprotein receptor(VLPLR)in males was decreased at 12 d (P<0.05), but was not affected by heat exposure at 23 d (P>0.05).These results suggest: 1) the effects of chronic heat exposure on growth performance is different in sex. 12 d heat exposure significantly depressed male and female weight gain. With the prolonged exposure time, weight gain of males decreased more severely, but females were not affected; 2) With the prolonged exposure time, fat deposition of males gradually decreased, but decreasing degree in females were relieved; 3) With the prolonged exposure time, decreasing degree of circulating lipid flux, the activities and expression of LPL in females were relieved, the concentration of TG in plasma and the activities of LPL in males decreased more severely; 4)The activities and expression of LPL in adipose tissue, plasma concentration of FFA,TG,VLDL maybe be useful as indices when investigating effects of heat exposure on fat metabolism of broilers.