Reproduction, Breeding and Artificial Insemination
Domain 8: Reproduction, Breeding and Artificial Insemination
This domain tests the oestrous cycle, heat detection, timing of insemination, semen handling and breeding systems. The exam may give a heat observation time and ask when to inseminate.
Core facts
- Oestrous cycle: cattle about 21 days (18 to 24), buffalo about 21 to 23 days; standing heat lasts roughly 12 to 18 hours.
- Ovulation occurs near the end of standing heat, so insemination should be about 12 hours after the first standing heat, following the AM to PM rule.
- Gestation: cattle about 280 to 285 days, buffalo about 305 to 310 days.
- Semen handling: thaw frozen straws in water at 35 to 37 degrees Celsius for the recommended time, handle gently, and inseminate with clean technique.
- Breeding systems: inbreeding, line breeding, outcrossing, crossbreeding and grading. Crossbreeding is used for heterosis but needs a planned mating system.
Worked example
A cow is first seen standing to be mounted at 6 a.m. Reason: count about 12 hours from first standing heat, so inseminate in the evening of the same day. If she is still in standing heat the next morning, a repeat insemination may be advised by the veterinarian. Inseminating immediately at 6 a.m. is usually too early because ovulation has not occurred.
Traps
Using the same gestation length for cattle and buffalo; thawing semen in hot water or without a thermometer; and confusing first observed heat with first standing heat.