Study On The Co-relationship Between The Polymorphism Of Blood Proteins, Microsatellites And The Prolificacy In Six Breeds/Strains Of Sheep

In order to select the genetic maker of prolificacy in sheep and increase the efficiency of prolificacy colony selection, the polymorphism of 3 blood protein loci (haemoglobin (Hb), transferring (Tf) and esterase (Es)) and 3 microsatellite loci (OarAE101,BM143 and OarHH35) in Small Tail Han sheep (STH), Poll Dorset (PD), Suffolk (S) and China Merino (Xinjiang type) (including Prolific strain (PS),Meat strain (MS) and Large Frame strain (LFS) ) were tested, and the co-relationship between different genotypes and litter size was also identified. The polymorphism of blood proteins were tested by discontinuous polyacrylamide gel electrophoresis in 43 STH, 58 PD, 56 S, 29 PS, 30 MS and 29 LFS. The lambed ewe of STH, PD, S, PS, MS and LFS was 34, 37, 35, 29, 30, 29 respectively.The polymorphism of microsatellites were studied by means of PCR, poyacrylamide gel electrophoresis and silver staining. 42 STH, 52 PD, 44 S, 29 PS, 30 MS and LFS were selected for the experiment including 34, 35, 30, 29, 30, 29 lambed ewe respectively.The results of blood protein markers showed that in S the ewe with HbBB genotype had a higher average litter size than that of HbAB genotype (P<0.01), being 1.81±0.40 and 1.00±0.00 lamb/litter respectively. It showed the correlation between HbBB genotype and prolificacy. In PD the ewe with the HbAA or HbAB genotype produced twins, and that the ewe with HbBB genotype only bred 1.64±0.49 lamb/litter, indicating the correlation between HbA allele and prolificacy. However, there was no significant difference of prolificacy between various Hb genotypes in other 4 breeds/strains. The average litter size of TfBB genotype in STH was highest, being 3.5 lamb/litter, significantly higher than that of TfAB genotype(1.50±1.00 lamb/litter), so TfBB genotype could be applied in early selection for colony of litter size more than 3 lamb. The TfAC genotype in MS and the TfAA, TfCC genotypes in LFS had a prolific tendency, and the average litter size of TfCC genotype(1.50±0.71 lamb/litter) in LFS was significandly higher than TfAC genotype(1.00±0.00 lamb/litter). However, there was no significant difference of prolificacy between Tf genotypes in other 3 breeds/strains. The ESa phenotype in both PS and STH had a tendency of prolificacy, which indicated the elimination of ESA genotype could increased the litter size. However, there was no significant difference between ESa genotype and ESA genotype in other 4 breeds/strains.The results of microsatellites showed that the microsatellite markers for prolificacy characteristics could be as follows: OarHH35 117bp/121bp and OarAE101 103bp/111bp in STH, OarHH35 127bp /141bp, BM143 104bp/114bp and OarAE101 103bp/103bp in Chinese Merino PS, OarAE101 111bp/111bp and BM143 112bp/122bp in Chinese Merino MS, and BM143 112bp/122bp in Suffolk. The Suffolk ewes with the genotypes of OarHH35 125bp/139bp, 127bp/141bp produced single lamb,and therefore these microsatellite markers could be used for elimination in Suffolk.This study reveals a breeds/strains difference of prolificacy genotype in blood protein loci and microsatellite loci, which indicates that the selection of prolificacy characteristics in sheep should depend on different genotype in different breeds/strains.