Reproduction traits of heterozygous<i>myostatin</i>knockout sows crossbred with homozygous<i>myostatin</i>knockout boars

Abstract

Abstract Few studies exist on homozygous myostatin gene mutant ( MSTN −/− ) pigs, especially on their reproductive ability. We have previously shown that semen quality of homozygous MSTN −/− boars is comparable to that of wild type (WT). However, no data exist on the reproductive ability of heterozygous MSTN gene mutant ( MSTN +/ − ) sows. The present study highlights showed that the heterozygous MSTN +/ − sows have delayed pubertal age than WT sows (255.80 ± 6.79 versus 191.10 ± 3.42, respectively). The number of services per pregnancy of heterozygous MSTN +/ − sows is significantly higher than that of WT sows (3.33 ± 0.43 versus 1.60 ± 0.25, respectively). Moreover, although heterozygous MSTN +/ − sows have natural reproduction ability, their litter size was significantly lower than that of WT sows (7.75 ± 0.44 versus 14.25 ± 0.60, respectively). Offsprings generated from heterozygous MSTN +/ − sow and homozygous MSTN −/− boar were genotyped with the PCR and sequencing method to detect myostatin mutation and to identify whether the piglets are homozygous MSTN −/− or heterozygous MSTN +/ − . The proportion of homozygous MSTN −/− piglets was significantly lower than that of heterozygous MSTN +/ − piglets (2.50 ± 0.35 versus 5.25 ± 0.60, respectively). Furthermore, none of the sows presented dystocia, and the phenotype of heterozygous MSTN +/ − piglets was normal. However, 10% homozygous MSTN −/− piglets died of dyspnoea within 2 hr after birth, 60% of homozygous MSTN −/− piglets showed large tongues, and 50% had umbilical hernias. In summary, this study for the first time reports the reproduction traits of heterozygous MSTN +/ − sows crossbred with homozygous MSTN −/− boars. This study will pave the way in a new direction for the breeding and development of super lean meat varieties in the future.