Reproduction traits of heterozygous myostatin knockout sows crossbred with homozygous myostatin knockout boars.

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.