Reproduction Glossary
9 essential reproduction terms explained — from Estrus to practical dairy farming knowledge.
Understanding Reproduction in Dairy Farming
Reproduction is the economic engine of every dairy operation. A cow must calve once per year to produce milk consistently. Every missed heat cycle costs 21 days of extended calving interval — roughly $6–10/day in lost production. Herds with >95% heat detection rate and <80 days open achieve 12–14 month calving intervals, maximizing lifetime milk production and genetic progress.
Key Principles
Heat Detection is King
Missed heats are the #1 cause of extended calving intervals. Use a combination of visual observation (2–3x daily), activity monitors, and tail paint. Target >95% detection rate.
95%+ detection rateBreed at the Right Time
Target breeding at 50–80 DIM for a 365-day calving interval. The breeding window is only 22 days (365 – 283 gestation – 60 dry). Every 21-day delay costs $60–100/cow.
50–80 DIMBody Condition Drives Fertility
Cows below BCS 5 at breeding have 20–30% lower conception rates. The hypothalamus suppresses GnRH when energy reserves are depleted. Calve at BCS 5–6.
BCS ≥5 at breedingProgesterone Guides Decisions
Milk progesterone testing detects non-cycling cows 30–45 days earlier than visual observation. Use CIDR protocols for anestrus cows.
<80 days openA
Anestrus
reproductionThe absence of estrus cycles. Cows fail to show heat. Common in early lactation, first-calf heifers, and energy-deficient cows. A leading cause of reproductive failure.
The deliberate introduction of semen into the female reproductive tract to achieve pregnancy. Used in 90%+ of US dairy cows. Enables genetic improvement and disease control.
C
Calving Interval
reproductionThe number of days between two consecutive calvings. Target: 12–13 months (365–400 days). Longer intervals reduce lifetime milk production.
D
Dry Period
reproductionA mandatory non-lactation period of 45–60 days before calving, allowing the udder to rest, regenerate tissue, and prepare for the next lactation.
E
The period in the reproductive cycle when a female cow is receptive to mating. Also called "heat," it typically lasts 12–18 hours.
G
Gestation
reproductionThe period from conception to calving. Average 283 days for dairy cattle (278–290 days by breed) and 310 days for buffalo.
L
Lactation
reproductionThe period of milk production following calving, typically lasting 305 days in dairy cows. Peak production occurs at 4–8 weeks post-calving.
P
Progesterone
reproductionA hormone produced by the corpus luteum (CL) on the ovary. It maintains pregnancy and prepares the uterus for embryo implantation. Tested via milk or blood.
V
The period after calving during which a farmer deliberately chooses not to breed the cow. Typically 50–80 days. Allows recovery before rebreeding.
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