The CCKAR Gene Polymorphism Is Associated With Feed Intake And Average Daily Gain In Broiler Chicken

The feed costs account for 60%of broiler production costs.It is one of the important ways to reduce the feeding cost by raising the utilization rate of broiler for breeding.Therefore,feed conversion rate(FCR)and residual feed intake(RFI)are common indicators for feed efficiency in domestic animal.RFI and FCR were evaluated,and the advantage and disadvantage of each for feed efficiency were compared in this study.At the same time,CCKAR gene was selected as a candidate gene according to the previous study,and the association between the SNPs of this gene and broiler feed intake was analyzed.Totally 1841 TianLu Black chickens were used in the present study,and their feed intake and body weight from 56-d old to 105-d old were daily recorded.The heritability of FC R and RFI from 56-d old to 105-d old were 0.312 and 0.282,respectively,indicating their moderate heredity.RFI is phenotypically independent of daily gain and medium metabolic weight,but there may be some genetic correlations(r_g=-0.198 and-0.125,respectively);There was a strong correlation between RFI and daily feed intake;FCR was negatively correlated with carcass weight,daily gain and testis(r_g=-0.835,-0.710 and-0.462,respectively);RFI was positively correlated with abdominal fat rate(r_g=0.542).FCR had higher relative selection efficiency than RFI on the weight and testicular weight.The result of CCKAR Polymorphism showed that:51 SNPs were found in CCKAR gene,4 of which could cause amino acid mutation.However,only the C334A and G1290A were significantly associated with the daily feed intake and daily gain(P<0.05).The AA type(mutant)was significantly higher than CC type(wild)at FI and ADG at locus C334A(P<0.05).The AA type(mutant)was significantly higher than GG type(wild)at FI at locus G1290A(P<0.05).Therefore,FCR is apply to weight selecting,and RFI is more appropriate if the breeding focus is feed intake and abdominal fat rate.And C334 A and G1290A of the CCKAR gene can be deemed as candidate markers for feed intake and weight gain.