- Cow health – lameness, old age, parasites and disease will reduce fertility.
- Bull fertility – must ensure that bulls are healthy and fertile. Young bulls may not be fully fertile even though they are well sized.
- Bull health – Hoof care is important to reduce lameness.
- Cow nutrition – peri-parturient (before and after calving) nutritional status effects conception rates. High phosphorous mineral supplementation has been shown to increase fertility.
Cows can successfully rear one calf per year. If the gestation period of a cow is 285 days, then she must be mated and in calf within 80 days of giving birth to maintain the calving interval.