Reproduction, Calving and Calf Rearing
Reproduction questions test the cycle, heat signs, gestation length, calving help and the first days of a calf's life.
Cycle and gestation
- Estrus cycle 18–24 days (average 21) in cattle, about 21 in buffalo but often silent.
- Heat lasts 12–18 hours; ovulation occurs about 10–14 hours after the end of heat; inseminate 12–18 hours after onset.
- Gestation: about 280 days in cattle, 305–310 days in buffalo.
- Pregnancy diagnosis by rectal palpation at 45–60 days or by ultrasound earlier.
Calving
Signs: udder filling, relaxation of the sacro-sciatic ligaments, mucus discharge, restlessness, water bag. Allow normal presentation (two front feet, head between) and progress; call the vet if there is no progress two hours after the water bag breaks or if presentation is abnormal. Do not pull with force.
Calf rearing
- Clean the nostrils, dry the calf, dip the navel in 7% iodine.
- Colostrum: 10% of body weight (about 3–4 litres for a 30 kg calf) within the first hour, and by 6 hours at the latest; antibodies are absorbed only briefly.
- Feed colostrum for 3–5 days, then whole milk at about 10% of body weight; introduce calf starter and clean water in week one; wean at 8–12 weeks when intake is adequate.
- Identify, weigh, record, and dehorn at 2–4 weeks.
Worked example
A cow was inseminated on 1 January. Expected calving = 1 January + 280 days = about 8 October. For a buffalo, add 310 days, giving about 7 November.
Traps
- Discarding colostrum as so-called first milk.
- Delaying colostrum beyond 6 hours.
- Pulling a calf before checking presentation.
- Weaning by age alone without checking starter intake.