| The Oula-type Tibetan sheep,also known as Oula sheep,is a breed of Tibetan sheep in Chinese and has been included in the National Livestock and Poultry Genetic Resources List.They have the advantages of outstanding product performance and high nutritional value of meat and can survive in the alpine and low-oxygen environment in the Qinghai-Tibet region.However,Oula sheep is a seasonal estrus breed,most of them produce only one lamb per litter,and the production efficiency is low,which has become the biggest obstacle restricting the development of the Oula sheep industry.Hu sheep is a unique breed with high fecundity in Chinese and is often used as the female parent for hybrid sheep production.Therefore,this study used Hu sheep,a prolific breed,to identify the polymorphism of its related molecular marker(Fec B gene).The Hu sheep ewes carrying the high fecundity Fec B gene homozygous GG type were screened out and crossed with the ram parent of the local Oula sheep to obtain the "Ou-Hu" F1 hybrid sheep carrying the Fec B gene.The polymorphisms of Fec B,GDF9-G1,and BMP15 gene g.50980656 T > C sites were analyzed in Oula sheep.To obtain the molecular markers related to the reproductive traits of Oula sheep,and provide the foundation for creating new breed of Ou-Hu hybrid sheep with high fertility.(1)The polymorphism of BMPR1 B gene Fec B mutation from 581 Hu sheep was detected by the Taqman-MGB probe method,and correlated with the litter size.The results showed that there were two genotypes,mutant homozygous genotype(GG)and mutant heterozygous genotype(GA),in the Hu sheep,but there was no wild type(AA).The frequencies of genotypes were 0.81 and 0.19,and the allele frequencies of G and A were0.91 and 0.09,respectively.The litter size of GG and GA from Hu ewes were 1.901 and1.900,respectively,and there was no difference between the two genotypes(p > 0.05).(2)The growth performance of Ou-Hu hybrid F1 lambs in different periods was analyzed.The weight,body length,and body height of Ou-Hu F1 lambs at birth,a week-old,and weaning period were higher than those of Hu sheep,showing bright growth performance.(3)The polymorphism of BMPR1 B gene Fec B mutation from 101 Oula sheep was detected by the Taqman-MGB probe method.The results indicated that only one of the Oula sheep carried the Fec B mutation,which is GA type,and the rest were AA type.Hardy-Weinberg has not reached the balance(p < 0.05),and the polymorphism information content(PIC)was 0.0098,which means low diversity.(4)The polymorphism of the GDF9 gene G1 site from 92 Oula sheep was detected by the PCR-RFLP method.Results indicated that there were two genotypes,mutant heterozygous genotype(A+)and wild type(++)in Oula sheep,the gene frequencies were0.67 and 0.33 respectively,and the allele frequencies of A and + were 0.335 and 0.665 respectively.It was in Hardy-Weinberg unbalance(p < 0.01),the PIC was 0.3462 which means moderate diversity.(5)The DNA sequencing was used to detect the polymorphism of the BMP15 gene g.50980656 T > C site from 92 Oula sheep.The results showed that there were three genotypes mutant homozygous genotype(CC),mutant heterozygous genotype(CT),and the wild type(TT).The gene frequencies of TT,CT and CC were 0.065/0.109/0.826,and the allele frequencies of C and T were 0.119 and 0.881 respectively.It was in Hardy-Weinberg unbalance(p < 0.01),the PIC was 0.1944 which means low diversity.In conclusion,these Hu sheep were highly homozygosis for Fec B mutation,and compared with Hu sheep,the F1 hybrid sheep crossed with Oula-type Tibetan ram have higher production performance.The Fec B,GDF9,and BMP15 gene,related to hyper-prolificacy,were detected in Oula sheep.The data from these preliminary studies lay the foundation for creating a new breed of "Ouhu" hybrid sheep. |
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