COWS ARE ON HEAT!....HOW DO YOU KNOW?

There is no doubt about it, a cow on heat can be spotted easily.  It is really important to notice when a cow is on heat. 

Estrus or heat is a certain time out of a 21 day cycle when a cow/heifer is receptive to breeding with a bull.  This time is approximately 6-24 hours.  The hormones play a role in the estrus process.

There are different behavioral and physical signs that indicate that a cow might be on estrus/heat. 

Behavioral signs

• The cow is very restless.  They are unable to rest or relax as a result of anxiety or boredom.  They move around back and forth looking for attention.

• The cow wanders around searching for a male, sniffing other cattle.  She does three to four times as much travel in that day.

• The cow will sniff the vulva of other cows, and other cows will also sniff her back.  Thus, sensing that she smells different.

• The cow interacts more with other herd mates, licking them and showing aggression. As a result, she picks fights with them.

• If there are several cows on heat, they gather together and ride each other like bulls. In the process, making bull sounds and fighting each other.

• More importantly, she will stand for other cattle to ride/mount her.  She places her chin on the back or rump of another cow to test whether the cow will stand to be mounted.  Bulls use this technique all the time.  They often rest their chins on the cow’s rump or loin to test whether she will stand before he tries to mount/ride her. 

• The cows on heat spend most of their time in these activities and spend less time eating or lying down, chewing the cud.  The milk production drops significantly.  In some cases, she may have a full udder if she is lactating.  This time is very stressful for calve because it does not get to suckle much. 

Figure showing white cow on heat being mounted and followed.

Physical signs

• A cow that is on heat secretes mucus from glands in the uterus, cervix and vagina.  This mucus aids in letting sperm swim up the tract to fertilize the egg.

• The cervix is relaxed and open in order to enable sperm from bull enter the uterus.

• There may be a discharge from the vulva (see figure below), transparent mucus that has the consistency of egg white.  It is viscous that it holds together in a long string.  This mucus is usually smeared on the cow’s buttocks and tail.

• The cow’s tail may be slightly raised and her vulva may be a bit enlarged and red in colour.

Post-mating 

• If the cow was bred, she will hold her tail out afterwards for several hours or days due to vaginal irritations. 

• The thrusting of the bull during mating and the irritation of the vagina will cause cause her back to be arched or curved.

• There may be a discharge from the bull’s seminal fluid on the cow’s vulva.  There is also sometimes a whitish yellow discharge from cow’s vulva a day or two after she is breed.