Generation of germline ablated male pigs by CRISPR/Cas9 editing of the NANOS2 gene

Genome editing tools have revolutionized the generation of genetically modified animals including livestock. In particular, the domestic pig is a proven model of human physiology and an agriculturally important species. In this study, we utilized the CRISPR/Cas9 system to edit the NANOS2 gene in pig embryos to generate offspring with mono-allelic and bi-allelic mutations. We found that NANOS2 knockout pigs phenocopy knockout mice with male specific germline ablation but other aspects of testicular development are normal. Moreover, male pigs with one intact NANOS2 allele and female knockout pigs are fertile. From an agriculture perspective, NANOS2 knockout male pigs are expected to serve as an ideal surrogate for transplantation of donor spermatogonial stem cells to expand the availability of gametes from genetically desirable sires

Synchronising oestrus with oestradiol benzoate after using a two-dose prostaglandin treatment to synchronise luteolysis in dairy heifers

Objective: To compare the reproductive performance and pattern of onset of oestrus in dairy heifers in which oestrous cycles were synchronised with two doses of prostaglandin (PG) F2aL and oestrus was synchronised with oestradiol benzoate (ODB).\ud \ud Procedure: Dairy heifers in two herds (herd A, n=192; herd B, n = 267) were treated with two doses of an analogue of PGF2aL (cloprostenol, 375 mUg, IM) 12 days apart. Heifers not detected in oestrus 48 h after the last dose of PGF2aL were either left untreated (No ODB, n=147) or treated with ODB (0.75 mg IM, n = 126). Onset of oestrus was monitored at 0, 24, 48, 80, 96 and 120 h after the last dose of PGF2aL Heifers were inseminated on detection of oestrus.\ud \ud Results: After the last dose of PGF2aL, oestrous detection rates at 80 h (43.5 vs 72.6%, P < 0.001), 96 h (74.1 vs 84.9%, P=0.025) and 120 h (78.2 vs 86.3%, P=0.082) were less in the No ODB compared to the ODB heifers, respectively. Conception rates (percentage pregnant that were inseminated) were greater in the No ODB compared to the ODB heifers (64.3% vs 47.6%, respectively; P=0.006), while pregnancy rates (percentage pregnant that were treated) were also greater in the No ODB compared to the ODB heifers, but differences were not significant (50.3% vs 41.1%, respectively; P = 0.068).\ud \ud Conclusion: Administration of ODB to heifers not in oestrus 48 h after a two-dose PGF2aL treatment increases the percentage of heifers detected in oestrus by 80 h, 96 h and 120 h after treatment, by an estimated 29%, 11% and 8%, respectively. However, administration of ODB decreases conception rates by an estimated 17%, and may decrease pregnancy rates (estimated 9% difference). Results are consistent with the hypothesis that ODB can increase submission rates but reduce conception rates following a two dose treatment with PGF2aL