Do Cows Have Periods?

do cows have period

Do cows have periods? If they do, what would cow menstruation like? How often is their menstrual cycle?

If you own cattle, or in this case, cow(s), it’s important to understand how they reproduce and the hormonal changes they will experience through time. This article will give you answers to all those questions.

*This post may have affiliate links, which means I may receive commissions if you choose to purchase through links I provide (at no extra cost to you). As an Amazon Associate I earn from qualifying purchases. Please read my disclaimer for additional details.

Do cows have periods? 

Yes, cows do menstruate, but not like the way that human does. The cows’ menstruation is called heat.

When a heifer is between 6 and 15 months of age, she reaches puberty, menstruation comes along, depending on the breed. This wouldn’t mean that she is ready for breeding.

A female cow should not be used for breeding until she is at least 18 months old. Servicing her too soon will impair her growth and result in decreased fertility and milk yield.

A cycle indicates the time period that spreads from one heat to the next. Female cows with strong reproductive health should experience these cycles fluidly and even predictably.

A cow’s sexual cycle is not seasonal. However, a rest period can occur in winter and spring if there is a limited feeding condition or opposing weather conditions. Heat cycles also include hormonal changes that cows are experiencing from heat to heat.

Female cows go into heat regularly when they are reproductively mature and not expecting. Their menstrual cycles take about three weeks or so, between 18 and 24 days, sometimes longer depending on the cow.

In general, you can expect a cow’s heat cycle to begin around the 21-day mark. The most fertile period can last between three to 24 hours, with the average time being 16 hours. In about two months after calving, the heat cycles will come back.

An estrous cycle can be divided into four phases: proestrus, estrus, metestrus, and diestrus. Estrus is the shortest yet plays the most important part in the reproductive game.

Estrus is characterized by standing behavior. This is the part that cows are in true heat. At this 3-24hrs period, they stand still to be mounted by other cows or step forward slightly with the mounting cow’s weight. Cows that move away quickly while trying a mount are not in true estrus.

Read more: 100+ Famous, Inspirational & Funny Cow Quotes and Sayings

How to know whether cows are in heat? 

Besides the standing heat that is easy to notice, there are many secondary signs to determine whether your cows are in heat as well.

Such symptoms may appear before, during, or after standing heat, and are not correlated with ovulation time.

cows in heat

1. Mounting other cows

An indication the cow is in heat or near heat could be the act of mounting other cows. Although it is not a primary indication of heat, for standing behaviour, you should watch cows demonstrating this activity closely.

2. Mucus discharge

Mucus is an indirect outcome during estrus with elevated estrogen levels. On the cow’s tail, thighs, flanks, or perineal area, you may find long viscous, transparent elastic strands of mucus dangling from the vulva or smeared mucus. However, until a cow is palpated during fertilization, mucus will often not appear externally.

3. Swelling and reddening of the vulva

The vulva swells during the heat and the interior get moist and red. These signs usually occur before the heat and persist after heat for a brief duration of time. The lips of the vulva are pale and more difficult to separate throughout the mid-cycle.

4. Bellowing, restlessness and trailing

Bovines in heat are more anxious and alert to their surroundings. While their fellows laying down resting, they remain standing and alert. They often trail behind and try to mount to other cows when allowed to interact.

Although these are not conclusive signs of heat, bovines showing such acts should be observed closely for standing behaviour.

5. Rubbed tailhead hair and dirty flanks

As a result of being ridden, the hair on the tailhead and back end is fluffed-up, rubbed, or tangled, and the skin may be uncovered. The legs and flanks may be spread with mud or excrement.

6. Chin resting and back rubbing

Before mounting, cows regularly rest or rub their chin on the targeted’s rump or back. This act shows that both cows should be watched for mounting and standing behavior.

7. Sniffing and licking

Sniffing the genitalia and licking the vulva of other’s happen much more regularly with cows in proestrus and estrus.

8. Head raising and lip curling

For the most part, this action follows sniffing of the genitalia and occurs more regularly if the cow being examined is in heat.

9. Decreased feed intake

Studies show that estrus cows spend less time feeding. Some of these studies also show that there is a decreased milk yield during this period.

10. Metestrous bleeding

Some bovines and most heifers have a bloody mucus release one to three days after estrus. High estrogen levels during estrus cause blood to spill from vessels close to the surface of the uterus. These cows with this symptom should be watched closely for a return to heat in 18 or 19 days.

Read more: Can Cows swim?

Why is it important to know your cows’ menstrual cycles? 

Early detection of when a cow is in heat and proper timing of artificial insemination is the key to maintain efficient and profitable reproductive performance.

Early detecting menstrual cycles in the breeding season or good timing of insemination thanks to proper heat detection results in optimizing calving intervals and semen expense.

Failure to detect cows’ heat period is a major factor that causes low fertility, hence the economic loss.


All mammals have menstrual cycles. Cows have no exception. Hopefully next time someone asks you whether cows have period, you could enlighten them with confidence.

Leave a Reply

Your email address will not be published. Required fields are marked *