Table 1. Odds ratios of the variables included in the final logistic regression model for factors affecting conception rate after treatment in high-producing dairy cows.
| Factor | Class | n | % CRa | Odds ratio | 95% Confidence interval | P |
| Treatment* × season | Control × cool | 1119/3975 | 36.4 | Reference | ||
| Control × warm | 441/1540 | 28.6 | 0.7 | 0.6–0.8 | <0.001 | |
| PEG × cool | 331/847 | 39.1 | 1.1 | 0.9–1.3 | 0.15 | |
| PEG × warm | 170/419 | 40.6 | 1.2 | 0.9–1.4 | 0.09 | |
| Treatment × parity | Control × primiparous | 562/1550 | 36.3 | Reference | ||
| Control × multiparous | 998/3065 | 32.6 | 0.8 | 0.7–0.9 | 0.006 | |
| PEG × primiparous | 161/412 | 39.1 | 1.1 | 0.8–1.3 | 0.4 | |
| PEG × multiparous | 340/854 | 39.8 | 1.1 | 0.9–1.3 | 0.1 | |
| Treatment × repeat breeding syndromeb | Control × 0 | 1130/3123 | 36.2 | Reference | ||
| Control × 1 | 429/1489 | 28.8 | 0.7 | 0.6–0.8 | <0.001 | |
| PEG × 0 | 335/912 | 36.7 | 1.0 | 0.8–1.1 | 0.9 | |
| PEG × 1 | 166/354 | 46.9 | 1.5 | 1.2–1.9 | <0.001 |
P=0.0001. R2 Nagelkerke=0.15. *Treatment: Control = natural estrus; PEG = prostaglandin F2α and eCG given on the day of sub-estrous diagnosis (presence of a corpus luteum), GnRH given 48 h later and FTAI conducted 24 h after GnRH treatment. a Conception rate. b Repeat breeding syndrome: 0 ≤ 3 AI; 1> 3 AI.