Table 5. Effect of transfer manners on in vivo development of cloned embryos.
| Transfer manners | No. surrogates (transferred embryos) | No. pregnancy (%) | No. delivery (%) | No. piglets (mean ± SEM) | No. piglets alive (mean ± SEM) | Cloning efficiency (%) |
|---|---|---|---|---|---|---|
| Normal transfer for preovulation | 15 (2550) | 9 (60.00 ± 12.66) | 8 (53.33 ± 13.36) | 25 (1.67 ± 0.55) | 15 (1.00 ± 0.36) a | 0.60 ± 0.23 a |
| Follicle puncture for preovulation | 9 (1545) | 7 (77.78 ± 16.34) | 6 (66.67 ± 17.25) | 25 (2.78 ± 0.70) | 20 (2.22 ± 0.46) b | 1.44 ± 0.30 b |
| Transfer position shallowed for preovulation | 6 (1010) | 4 (66.67 ± 20.01) | 3 (50.00 ± 21.13) | 9 (1.50 ± 0.86) | 6 (1.00 ± 0.56) a b | 0.69 ± 0.37 a b |
| Normal transfer for postovulation | 21 (3835) | 9 (42.86 ± 10.97) | 6 (28.57 ± 9.71) | 18 (0.86 ± 0.36) | 9 (0.43 ± 0.19) | 0.21 ± 0.10 |
| Transfer position deepened for postovulation | 7 (1230) | 2 (28.57 ± 19.00) | 1 (14.29 ± 16.81) | 3 (0.43 ± 0.62) | 1 (0.14 ± 0.33) | 0.08 ± 0.17 |
Follicle puncture, not transfer position change, significantly increased the average number of live piglets and cloning efficiency.
Normal transfer referred to that cloned embryos were transferred to the oviduct ampulla, which is about 10 cm away from umbrella; follicle puncture was that all the large developed follicles were punctured when surrogate gilts under preovulation; and, transfer position shallowed or deepened was that transfer position was about 8 cm or 12 cm away from umbrella.
The rates of pregnancy and delivery and the average numbers of piglets born and alive were based on the number of surrogates.
Cloning efficiency was calculated by total number of live cloned piglets/total number of transferred cloned embryos.
a,bValues in the same column with different superscripts differ significantly (P < 0.05).