Table 3. Effect of surrogate estrus stage on in vivo development of cloned embryos.
| Day of estrus | No. surrogates (transferred embryos) | No. pregnancy (%) | No. delivery (%) | No. piglets (mean ± SEM) | No. piglets alive (mean ± SEM) | Cloning efficiency (%) |
|---|---|---|---|---|---|---|
| Day 1 | 11 (1810) | 6 (54.55 ± 13.83) a | 6 (54.55 ± 14.45) a b | 26 (2.36 ± 0.82) a b | 18 (1.64 ± 0.56) a b | 1.09 ± 0.35 a b |
| Day 2 | 20 (3320) | 18 (90.00 ± 10.26) b | 16 (80.00 ± 10.72) a | 75 (3.75 ± 0.61) a | 51 (2.55 ± 0.42) a | 1.58 ± 0.26 a |
| Day 3 | 14 (2505) | 7 (50.00 ± 12.26) a | 7 (50.00 ± 12.81) a b | 29 (2.07 ± 0.73) a b | 17 (1.21 ± 0.50) b | 0.64 ± 0.31 b |
| Day 4 | 7 (1215) | 4 (57.14 ± 17.34) a b | 3 (42.86 ± 18.11) a b | 8 (1.14 ± 1.03) b | 5 (0.71 ± 0.70) b | 0.37 ± 0.44 b |
| Day 5 | 5 (985) | 2 (40.00 ± 20.51) a | 1 (20.00 ± 21.43) b | 2 (0.40 ± 1.22) b | 1 (0.20 ± 0.83) b | 0.08 ± 0.52 b |
Group of surrogate gilts with estrus on Day 2 displayed significantly higher rates of pregnancy and delivery, average numbers of piglets born and alive, and cloning efficiency.
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).