Variable | Level | Estimatec | SE | Hazard ratio (eb) |
---|
Herd | 1 | – | – | R |
2 | 0.14 | 0.12 | 1.15 |
3 | − 0.05 | 0.06 | 0.95 |
4 | 0.04 | 0.06 | 1.04 |
Age | Heifers 14‒15 months | – | – | R |
Heifers 16‒18 months | − 0.10a | 0.05 | 0.90 |
Heifers 19‒28 months | − 0.20a | 0.10 | 0.82 |
Cows parity 1‒3 | − 0.02 | 0.06 | 1.02 |
Initial follicle sized | ≤ 10.0 mm | 0.05 | 0.04 | 1.05 |
> 10.0 mm | – | – | R |
Diameter at ovulationa,e | 9.0‒15.0 mm | – | – | R |
15.1‒17.4 mm | − 0.15b | 0.05 | 0.86 |
17.5‒23.0 mm | − 0.12a | 0.06 | 0.89 |
BCS | Lean (2.5‒2.9) | 0.07 | 0.07 | 1.07 |
Moderate (3.0‒3.4) | – | – | R |
Fat (3.5‒4.0) | 0.08 | 0.05 | 1.08 |
- Hazard ratio for time to ovulation by herd, and classes of age, initial follicle size, follicle diameter at ovulation, and body condition score (BCS) in Norwegian Red cattle; time variable: hours from GnRH analogue treatment to ovulation; R, reference value and SE, standard error
- aOverall association with time to ovulation or within variable difference relative to the reference value; P ≤ 0.05
- bWithin variable difference relative to the reference value; P < 0.001
- cEstimate for each parameter level
- dDiameter (mm) of the dominant follicle at the time of GnRH analogue treatment (T0)
- eDiameter (mm) of the dominant follicle at the time of ovulation