Animal Breeding and Genetics
What this domain tests
Animal Breeding and Genetics tests heat detection, artificial insemination (AI), selection, crossbreeding and the genetic basis of milk yield. Questions often use Maharashtra breeds - Deoni, Pandharpuri buffalo and Osmanabadi goat - and ask you to choose a breeding plan.
Core rules
- Estrus: cattle cycle 18–24 days (average 21); heat lasts 12–18 hours; ovulation occurs about 10–12 hours after the end of heat. Best AI time is 12 hours after standing heat, or use the am–pm rule.
- Gestation: cattle 280–285 days; buffalo 305–310 days; goat 150 days; sheep 147 days; pig 114 days.
- Selection: response per generation R = h² × S, where h² is heritability and S the selection differential.
- Crossbreeding: use exotic semen (Holstein Friesian, Jersey) on local cows for heterosis; keep 50–75% exotic inheritance in field animals, not 100%.
- Conservation: breed Deoni and Pandharpuri pure; use grading up only for non-descript stock.
Worked example
A herd's milk yield has h² = 0.25. You select bulls and cows whose average yield is 400 kg above the herd mean. Expected genetic gain per generation = 0.25 × 400 = 100 kg. If the generation interval is 5 years, gain per year ≈ 100/5 = 20 kg. This shows why accurate records and progeny testing matter more than one high-yielding cow.
Traps that cost marks
Confusing heritability with repeatability; assuming crossbreds are always better without checking feed and management; using one bull for years (inbreeding); recording heat at the wrong time; forgetting that AI needs a trained technician and liquid nitrogen for semen.