118 Semen quality and fertilization ability of myostatin-knockout boars

Abstract

Myostatin-knockout (MSTN^−/−) pigs may provide a source of healthy lean protein for human consumption. However, little is known about the effect of this knockout on semen quality, which is important if these pigs are used for production. The purpose of this study is to evaluate the semen quality and fertility of MSTN^−/− boars. We generated MSTN^−/− boars from Duroc-Landrace-Yorkshire hybrid pig cell lines by somatic cell nuclear transfer, and all 12 boars showed sexual maturation with an obvious “double muscling” phenotype. Semen was collected randomly from three MSTN^−/− boars using the gloved-hand technique by one technician and then tested by computer-assisted semen analysis. Semen acrosomal integrity and deformity were measured using Coomassie blue- and eosin-stained smears, respectively. Sperm plasma membrane integrity and mitochondrial activity were evaluated by Hoechst 33342, propidium iodide, and JC-1 multiple staining. The reproductive performance of MSTN^−/− boars was evaluated by IVF and by AI. All data were analysed by Student's t-tests. The results showed that the semen color, odor, and pH had no abnormalities. The concentration, motility, plasma membrane integrity, deformity, acrosome integrity, and mitochondrial activity of the semen presented no significant differences from those of the control semen (Duroc). The ejaculation volume of the MSTN^−/− boars was significantly lower than that of the control (168.78 ± 6.70 and 223.11 ± 21.21 mL, respectively), although the total sperm number was not significantly different. The rate of cleavage and blastocyst formation (247 to 254 oocytes per boar) was not significantly different from those of the control (69.1 ± 0.7 vs. 65.2 ± 1.6%, and 20.2 ± 1.2 vs. 22.8 ± 1.4%, respectively). Seventeen healthy offspring were successfully produced from three sows through AI using semen from one MSTN^−/− boar. However, the genotype of piglets has not been tested at present. Thus, MSTN^−/− boar may be used as sires, and these pigs are expected to be developed to provide new super-lean meat varieties in the future.