Embryo transfer as a means to introduce new stock into SPF pig herds

Ovarian response, embryo recovery and results of embryo transfer in a Hungarian native pig breed

The objective of the study was to use embryo transfer (ET) for propagation of the Swallow Belly Mangalica population. Mangalica is a native Hungarian pig breed adapted to extreme climate and housing conditions and distinguished for excellent meat and fat quality. However, due to their weak reproductive characteristics and relatively high fat proportion, Mangalica pigs have been replaced by modern breeds. Now, there is an increased interest again to safeguard the properties of this breed. We conducted two experiments. First, we used a total of 18 puberal Mangalica gilts to determine an optimal superovulatory treatment. Following estrus synchronization with Regumate, we injected gilts with either 750, 1000 or 1250 IU PMSG, followed by 750 IU hCG 80 h later. We scanned ovaries endoscopically 3 days after hCG administration. The application of 1000 and 1250 IU PMSG resulted in a higher rate of ovulation compared to 750 IU (24.2 +/- 3.6 and 21.0 +/- 2.3 vs. 13.7 +/- 2.7 P<0.05). The number of follicular cysts increased after administration of 1250 IU PMSG compared to 750 and 1000 IU (2.0 +/- 1.3 vs. 0.3 +/- 0.7 and 0.2 +/- 0.3, P<0.05). Thus, we chose 1000 IU PMSG for further stimulation of Mangalica gilts. In the second experiment, we induced superovulation in 10 Mangalica donor gilts by 1000 IU PMSG and 750 IU hCG. Gilts were fixed-time inseminated, and then five days later embryo collection was carried out surgically (n=6) or endoscopically (n=4). Out of the 187 ova recovered, 92.5% were at the morula/blastocyst stage. The embryo recovery rate was higher following surgical flushing than following endoscopy (91.5 +/- 4.4% vs. 71.4 +/- 12.7%, P<0.05). Altogether 143 embryos were transferred surgically or endoscopically into 8 Landrace recipients. Surgical and endoscopic transfer of Mangalica embryos into Landrace gilts resulted in pregnancies in 3 and 2 gilts, respectively; thus the overall farrowing rate was 62.5%. The birth of 59 Mangalica piglets from 5 embryo recipients equals an average litter size of 11.8 +/- 1.3, which is two times larger than usual in this breed. Therefore, we concluded that an appropriate inter-breed ET program is a suitable tool to propagate the endangered Mangalica breed.

Practical experience with commercial embryo transfer in pigs

Embryo transfer was used to introduce new genetic material into 5 commercial specific-pathogen-free pig herds in south eastern Queensland in order to reduce the risk of disease transmission. The embryos were collected surgically from gilts and sows and transferred surgically to synchronised recipient sows on the farms within 12 h. A total of 751 embryos were collected from 37 donors of which 665 were transferred to 39 recipients. Thirty-one (79.5%) farrowed with an average litter size of 8.1 +/- 3.0. The methods used to synchronise oestrus and superovulate the donors, together with a detailed description of the surgical technique are presented and discussed in relation to practical problems and limitations of the use of embryo transfer in swine.