Study On DNA Molecular Markers And Its Related On Prolificacy And Weight In Crossbreed Sheep

Two types of crossbreeds sheep of (Tan×Xiao-tails Han)×German Merino and (Tan×Xiao-tails Han)×Poll Dorset were screened with forced PCR-SSCP, PCR-RFLP and microsatellite methods to study the polymorphism and their effects on litter size and body weight. The purpose of this study is to offer some theory reference for development of improvement of sheep breeding and production capability. The study results were as follows:( 1) The GDF9 gene have two genetypes in the two types of crossbreeds sheep respectively(AA,AB). In the crossbreed sheep of(Tan×Xiao-tails Han)×German Merino, the genotype frequencies were 0.09(AA), 0.91(AB);In the crossbreed sheep of (Tan×Xiao-tails Han)×Poll Dorset , the genotype frequencies were 0.19(AA), 0.81(AB). Results within the crossbreed sheep of (Tan×Xiao-tails Han)×Poll Dorset showed that the mean litter size of ewes with genotype AA is 2.50 and higher than that of AB significantly (1.68, P<0.05). Results within the crossbreed sheep of (Tan×Xiao-tails Han)×German Merino showed that the mean litter size of ewes with genotype AA is 2.67 and higher than that of AB significantly (1.96,P<0.05).(2) The FecB genes have two genetypes in the two types of crossbreeds sheep respectively(CC,CD). In the crossbreed sheep of(Tan×Xiao-tails Han)×German Merino, the genotype frequencies were 0.53(CC), 0.47(CD). In the crossbreed sheep of(Tan×Xiao-tails Han)×Poll Dorset , the genotype frequencies were 0.58(CC), 0.42(CD). Results within the crossbreed sheep of (Tan×Xiao-tails Han)×Poll Dorset showed that the mean litter size of ewes with genotype CD is 2.33 and higher than that of CC significantly (1.50, P<0.05) . Results within the crossbreed sheep of(Tan×Xiao-tails Han)×German Merino showed that there is little difference in the mean litter size between genotype CD and genotype CC.(3) The results showed that AB genotype was negatively correlative with litter size of two types of crossbreeds sheep remarkably; CD genotype was positively correlative with litter size of (Tan×Xiao-tails Han)×Poll Dorset remarkably.FecB gene and GDF9 gene have little effect on both weaning body weight and birth body weight to the two types of crossbreeds sheep.(4) The BM143 and BMS0772 microsatellite have polymorphism in the two types of crossbreeds sheep .16 alleles were got in the BM143 and BMS0772 microsatellite. There were 10 alleles in BM143 microsatellite and 6 alleles in BMS0772 microsatellite. The PIC of 2 microsatellite loci all reached high polymorphisms (PIC>0.7) and both of them are perfect markers.(5) BM143 has no prominent affect to litter size and weight of the two types sheep. Genotype 97/127 of BMS0772 has best prominent affect to weaning weight of the crossbreed sheep of (Tan×Xiao-tails Han)×German Merino. BMS0772 has no prominent affect to litter size.