Table 5. Least-squares means and standard errors of pregnancy rate (%) after transfer of embryos frozen-thawed in propylene glycol, ethylene glycol or glycerol.
| Effect | Probability | No. of transfers | Least-squares mean | Standard error | |
|---|---|---|---|---|---|
| (No. of pregnancies) | |||||
| Overall mean | 1273 (545) | 33.3 | 2.39 | ||
| Cryopreservation | P < 0.05 | ||||
| Propylene glycol | 400 (144) | 27.2 b | 3.09 | ||
| Ethylene glycol | 418 (187) | 34.5 a | 3.14 | ||
| Glycerol-Ie | 177 ( 86) | 33.5 ba | 4.52 | ||
| Glycerol-IIf | 278 (128) | 37.7 a | 3.08 | ||
| Region | P < 0.0001 | ||||
| 1 | 324 (137) | 34.8 bc | 3.87 | ||
| 2 | 228 (112) | 42.8 ab | 4.05 | ||
| 3 | 298 (164) | 46.7 a | 3.89 | ||
| 4 | 194 ( 50) | 10.4 d | 4.59 | ||
| 5 | 229 ( 82) | 31.6 cd | 4.00 | ||
| Developmental stage | P < 0.001 | ||||
| Compacted morulae | 278 (131) | 40.8 a | 3.42 | ||
| Early blastocysts | 377 (187) | 38.8 a | 3.15 | ||
| Blastocysts | 425 (160) | 28.3 b | 3.08 | ||
| Expanded blastocysts | 193 ( 67) | 25.1 b | 4.28 | ||
| Parity | P < 0.0001 | ||||
| Heifer | 791 (355) | 46.2 a | 2.41 | ||
| 1 | 207 ( 83) | 33.6 b | 3.72 | ||
| 2 | 139 ( 47) | 23.8 b | 4.47 | ||
| 3≤ | 136 ( 60) | 29.4 b | 4.60 | ||
| Corpus luteum qualityg | P < 0.001 | ||||
| Excellent | 477 (219) | 36.3 a | 2.73 | ||
| Good | 509 (222) | 36.9 a | 2.53 | ||
| Fair | 176 ( 50) | 22.8 b | 4.15 | ||
| Poor | 111 ( 54) | 36.9 a | 5.78 | ||
a, b, c, d Values within the same column with different superscripts differ significantly (P < 0.05). e Glycerol-I: glycerol-step wise dilution, f Glycerol-II: glycerol-in situ dilution, g Corpus luteum quality was classified into four categories based on size [43].