Research On Growth And Its Candidate IGF-I Gene Polymorphism And Its Tissue Distribution In Pigeon

Meat-type pigeon is one of the important members in domesticated poultry.With the improvement of living standard,the consumption and the industry of squab increaase rapidly.In the present study,production performances among four pigeon breeds were compared,and the SNP in Insulin-like growth factors-I gene(IGF-I)as well as the profile of IGF-1 mRNA expression was investigated.The results are helpful in choosing breeding materials and marker assisted selection in meat-type pigeonbreeding.Analysis based on the squabs of Silver King,White King,White Cardslave and Eurppean pigeon showed that the squabs grew fast in 0-14 d with daily gain 20.26-35.05g/d and the growth rate decreased in 21-28 d.The body weight at 28 d differed(P<0.01)among the 4 breeds with the European pigeon was the highest(632g)and White King the lowest(410g),but the slaughter rate did not differed(P<0.05 or P<0.01)among the 4 breeds.The White King had the highest percentage of exiscerated body,and European pigeon had highest breast muscle rate(28.36%),and White Cardslave had highest leg rate(14.86%).The abdominal fate rateof European pigeon is the highest(1.79%)and White Wing the lowest(1.18%),however,the CV of abdominal fat rate was high(>40%).In body measurements,the body length,width of breast and innominate bone in White King were higher than Silver King(P<0.05 or P<0.01),but the breast bone length were lower than Silver King(P<0.01).By cloning and sequencing of exons and 5’-region of IGF-I,no DNA polymorip hism was found in the four exons.The exons homology rate with columba livia do mestica,gallus,cairna moschata,coturnix japonica,meleagris gallopavo and anser w ere 100%,99.3%,98.2%,98.6%,97.4%,and 96.1%,respectively.In primer P1 PCR product 4 SNPs including C-355 T,C-361 T,A-369 C and T-384 C were indentified,in which C-355 T,C-361 T,A-369 C were in genetic linkage,exhibiting 3 genotypes CC(0.31),CD(0.55),DD(0.14),with the allelic frequencies of C and D were 0.59 and 0.41,respectively.In White King pigeon,the percentage of breast muscle at 28 d of C C was higher(P<0.05)than that of CD.In primer P2 PCR product G-1182 Twas in dentified,it exhibited genotypes EE(0.30),EF(0.54),FF(0.16),with the allelic fr equencies of E and F were 0.57 and 0.43,respectively.InWhite King,the body we ight at 28 d of FF was higher(P<0.05)than that of EE.The IGF-I mRNA expressions in breast muscle,leg muscle and liver were detected by RT-PCR.The level of IGF-I mRNA in liver and breast muscle decreased during 0-14 d,while it reached to peak at 14 d in leg muscle.The level of IGF-I mRNA in liver were significantly higher r than that in breast and leg muscle(P<0.01).The level of IGF-I mRNA in breast was higher(P<0.01)than that in leg muscle in 0 and 7d,but lower(P<0.01)in 14 and 28 d.