The effect of artificial insemination prior to transfer of a limited number of vitrified and warmed porcine embryos by open pulled straw (OPS) method on their survival ability for farrowing

Piglet production by non-surgical transfer of vitrified embryos, transported to commercial swine farms and warmed on site

We investigated the feasibility of piglet production by non‐surgical embryo transfer (Ns‐ET) of vitrified porcine blastocysts and expanded blastocysts transported to commercial farms and warmed on site (V/T/W embryos). Ns‐ET was performed by depositing 11–20 vitrified and warmed embryos at a proximal site within the uterus via a catheter. In Experiment 1, the effect of donor–recipient estrous cycle asynchrony on the efficiency of Ns‐ET of vitrified and ordinary warmed embryos was investigated at the experimental facility. With a 1‐day delay recipients relative to that of donor, the farrowing rate was 50.0% and the survival rate to term was 21.1%. In Experiment 2, Ns‐ET using recipients with a 1‐day delay and vitrified embryos after one‐step warming and dilution was evaluated at the experimental facility. Although the resulting farrowing rate was 42.9%, the survival rate was 6.4%. In Experiment 3, Ns‐ET was conducted using V/T/W embryos at four commercial farms, where piglets derived from them were produced. When artificial insemination was conducted prior to Ns‐ET, the farrowing and survival rates obtained using V/T/W embryos were 75.0%, and 21.3%, respectively. These results show that Ns‐ET of V/T/W embryos using this protocol would be feasible for piglet production at farms.

Insemination of recipient sows improves the survival to term of vitrified and warmed porcine expanded blastocysts transferred non-surgically

This study was performed to evaluate reproductive performance after non‐surgical embryo transfer (Ns‐ET) of 10–15 porcine expanded blastocysts (ExBs) that had been vitrified and warmed (V/W) using the micro volume air cooling (MVAC) method. The effect of asynchrony between the donor and recipient estrous cycle was investigated. Ns‐ET was conducted in recipients whose estrous cycle was asynchronous to that of donors by a delay of 2, 1, or 0 days. In the 2‐day and 1‐day groups, the similar farrowing rates (27.3% and 25.0%) and survival rates to term (13.9% and 15.7%) were obtained after Ns‐ET of V/W ExBs. None of the recipients in 0‐day group farrowed. Artificial insemination (AI) prior to Ns‐ET was then evaluated. Ten–15 V/W ExBs were transferred non‐surgically to 12 recipients whose estrous cycles were asynchronous to that of donors by a 2‐day delay. All of the recipients produced piglets, and all (100.0%) delivered piglets were derived from the transferred V/W ExBs. The survival rate of V/W ExBs to term was 25.2%. These results demonstrate that Ns‐ET of V/W ExBs using MVAC can facilitate piglet production, even if 10–15 embryos are transferred. Moreover, piglets were obtained stably when AI was performed prior to Ns‐ET.