Next heat
Nov 19Watch Nov 15 to Nov 22
- Her next heat should start about Nov 19, 21 days after the last one.
- It is normal for it to come from Nov 15 to Nov 22 (day 17 to 24). Watch her then.
- A cow stays in heat about 15 hours, from less than 6 to close to 24. She ovulates 24 to 32 hours after heat starts.
- Heifers often cycle faster: 17 to 21 days, says Wisconsin.
Bred her? Find the due date: cow gestation calculator.
Her next heats
| Heat | About |
|---|---|
| 1 | Thursday, November 19, 2026 |
| 2 | Thursday, December 10, 2026 |
| 3 | Thursday, December 31, 2026 |
| 4 | Thursday, January 21, 2027 |
| 5 | Thursday, February 11, 2027 |
| 6 | Thursday, March 4, 2027 |
At the usual spacing. Each heat can come a few days early or late. When you see her in heat, type that new date.
Heat cycles by animal
| Animal | Days apart | Normal spread | In heat for |
|---|---|---|---|
| Cow | 21 | 17–24 | 15 hours, from less than 6 to close to 24 |
| Mare | 21 | 18–25 | 4 to 7 days |
| Goat | 20–21 | 17–24 | 30 hours |
| Sheep | 17 | 14–19 | 30 to 35 hours, from 20 to 42 |
| Pig | 21 | 16–25 | 40 to 60 hours |
The mare's spread is our sum: 4 to 7 days in heat, then 14 to 18 days out of heat (eXtension). The others are as the sources print them.
Questions
How often does a cow come into heat?
About every 21 days. Anything from 17 to 24 days is normal. Heat lasts about 15 hours.
How often does a horse come into heat?
A mare in the breeding season comes into heat about every 21 days. She stays in heat 4 to 7 days.
How often do goats come into heat?
Every 20 to 21 days, from 17 to 24. A doe stays in heat about 30 hours, says Langston University.
How often do sheep come into heat?
About every 17 days, from 14 to 19. Heat usually lasts 30 to 35 hours, says New Mexico State.
When does a sow come into heat after weaning?
About 4 to 7 days after weaning, says Purdue. Then about every 21 days.
Sources
- South Dakota State University FS921A, The Bovine Estrous Cycle (Iowa Beef Center)Jan 2004Cows: heat every 21 days (17 to 24); heat lasts about 15 hours
- University of Wisconsin-Madison Extension, Estrus Detection & Estrus Detection AidsAug 2023Cows 17 to 24 days; heifers 17 to 21
- eXtension Horses, Mare Reproduction: Typical CycleJan 2020Mares: 21 days; in heat 4 to 7 days, then out 14 to 18
- Langston University, Goat Reproductive BiologyundatedDoes: 20 to 21 days (17 to 24); heat about 30 hours
- New Mexico State University, Reproduction in SheepundatedEwes: 17 days (14 to 19); heat 30 to 35 hours
- Purdue Animal Sciences, sow reproductionundatedSows: heat every 21 days, lasting 40 to 60 hours; back 4 to 7 days after weaning
- West Virginia University Extension, Swine AI Guidelines for BeginnersundatedSows: 16 to 25 days
- University of Minnesota PIH-46, Care of the Sow during Farrowing and Lactation1978Sows back in heat 3 to 7 days after weaning