Table 2.
Ovarian activity and reproductive performance in first and second breeding and calving seasons of heifers sired by high and low residual feed intake EBV bulls (pHE vs. pLE)
| Paternal residual feed intake group | ||||
|---|---|---|---|---|
| pHE | pLE | SEM | P-value | |
| Ovarian activity previous AI | ||||
| Cycling, % (n/n) | 34 (21/62) | 22 (13/58) | — | 0.16 |
| Anestrous, % (n/n) | 66 (41/62) | 78 (45/58) | — | 0.16 |
| Superficial anestrus, % (n/n) | 44 (27/62) | 52 (30/58) | — | 0.55 |
| Maximum follicle diameter, mm | 8.6 | 7.8 | 0.4 | 0.04 |
| Maximum follicle diameter anestrous cows, mm | 8.0 | 7.9 | 0.5 | 0.79 |
| First breeding and calving seasons | ||||
| Inseminated heifers, % (n/n) | 79 (49/62) | 41 (24/58) | — | <0.01 |
| Pregnant day 30, % (n/n) | 42 (26/62) | 38 (22/58) | — | 0.81 |
| Cycling day 30, % (n/n) | 55 (34/62) | 48 (28/58) | — | 0.48 |
| Anestrus day 30, % (n/n) | 3 (2/62) | 14 (8/58) | — | 0.04 |
| Pregnancy, % (n/n) | 97 (60/62) | 95 (55/58) | — | 0.67 |
| Service to conception interval, d | 16.7 | 16.9 | 2.1 | 0.51 |
| Calving day, d | 25 | 33 | 3 | 0.05 |
| Second breeding and calving seasons | ||||
| Discarded after first breeding season, % | 5 (3/62) | 10 (6/58) | — | 0.53 |
| Pregnant day 30, % (n/n) | 5 (3/59) | 10 (5/52) | — | 0.59 |
| Cycling day 30, % (n/n) | 44 (26/59) | 48 (25/52) | — | 0.36 |
| Anestrus day 30, % (n/n) | 51 (30/59) | 42 (22/52) | — | 0.57 |
| Pregnancy, % (n/n) | 88 (52/59) | 83 (45/54) | — | 0.58 |
| Calving to conception interval, d | 104.8 | 101.4 | 5.1 | 0.61 |