Effects Of PIC Multi-vertebrate Trait And Related Mutation Loci On Carcass Weight In Pigs

The multi-vertebrate trait is usually manifested as the phenomenon that the number of vertebrae of livestock is more than that of normal individuals.In different livestock,the evaluation of the effect of this trait on the breeding benefit is different.Vertebral number affects the carcass length,and as a result,affects the carcass weight in pigs.From the perspective of economic benefits,vertebral number is an important indicator that affects carcass length and production in pigs.However,effects of increased vertebral number on carcass weight is different based on the results from different population in pigs.Presently,two mutation loci,NR6A1 g.748 T > C and VRTN g.20311₂0312 ins 291,are considered to be associated with the vertebral number in pigs.The frequency of haplotype of VRTN Ins was different in different pig populations,and the mutation mainly affected the number of thoracic vertebrae in pigs.However,it is controversial of the effect of this mutation on the carcass weight of pig as well.In this study,we investigated the production performance of PIC commercial pigs,and collected and analyzed 923 PIC commercial pigs’ spine number and carcass weight.To evaluate the effects of multiple vertebral trait and relative mutation on carcass weight,the muscle tissue was sampled for genetic analysis of the two mutations.The main results of this study are listed as follow.（1）PIC pig was superior to local hybrids in production and breeding performance,but the requirement to environment and nutrition level is higher.（2）There are variation of the vertebral number in PIC pig population.The number of thoracic vertebrae ranges from 13 to 17,dominated by 14,15,and 16.The number of lumbar vertebrae number ranges from 4 to 7,dominated by 5,6,and 7.The total number of thoracic and lumbar vertebrae ranges from 19 to 23,dominated by 20,21,and 22.（3）The carcass weight decreased with the increase of the number of thoracic vertebra and the total number of thoracic and lumbar vertebra,and increased with the increase of the number of lumbar vertebra.（4）No polymorphism was detected on the candidate NR6A1 g.748 T > C locus,with the T haplotype fixed in our PIC pig population.（5）There is polymorphism on the candidate VRTN g.20311₂0312 ins 291 locus,the haplotype frequencies of Ins and Wt are 0.3064 and 0.6936,respectively.The Wt haplotype is dominant.（6）The VRTN Ins haplotype can significantly increase the thoracic vertebrae number and the total number of thoracic and lumbar vertebrae,and decrease the lumbar vertebrae number.（7）The VRTN Ins haplotype can significantly decrease the carcass weight in out PIC pig population.These results further confirm the effects of multiple vertebral number on carcass weight and the effects of VRTN Ins haplotype on the thoracic and lumbar vertebral number,indicate that the VRTN Ins haplotype can affect the total number of thoracic and lumbar vertebrae.Our results provide significant information for evaluation of multiple vertebral trait and breeding in pigs.