While good weather can be of huge benefit for farmers, it can also be a roadblock if it hangs around for too long or is too intense.

It can make heat detection and breeding more difficult in myriad ways, and here are just a few of them:

Heat Stress

One conditions cattle can contract during periods of intense heat is heat stress. This can affect breeding in a number of ways in cattle, in both genders.

Diagram of cow in Heat Stress

Silent heats in cows and heifers

Heat stress can affect or hamper hormone production in cattle which can lead to cows or heifers not displaying signs of heat. This is known as silent heats, or subestrus.

Specifically, heat stress can cause an increase in cortisol secretion which has been reported to block estradiol and reduce estrus behavior.

four blonde cattle looking into camera

Bull fertility

Heat stress also affects the breeding performance of bulls. While hot weather in general can affect bull fertility (bull testes must be 2-6°C cooler than core body temperature for fertile sperm to be produced) heat stress can be detrimental to semen quality, testicular volume, sexual behavior.

This in turn affects conception rates, fertility rates and bull fitness.

One thing to bear in mind is that younger bulls are more susceptible to elevated air temperatures.

young red bull with a ring in his nose looking directly into camera


A long drought combined can lead to scorched fields and grass not growing. This is hugely problematic for breeding, as a poor diet can lead to heat detection becoming much more difficult.

This is because a cow’s nutritional intake can affect how strongly your cow or heifer displays signs of heat.

drought grass

If your cow isn’t getting enough green grass, this means they might not be getting enough minerals such as phosphorus, or trace elements like copper and cobalt, which all help promote the cow having a strong estrus.

Cattle can also suffer from a Vitamin A deficiency after a long drought due to the cow not getting enough beta carotene (which cows convert to Vitamin A) which is usually rich in green grass.

These deficiencies can be an issue during drought periods, or during winter, when grass isn’t as green. Drought can compound vitamin A deficiency because plants go dormant early in the year and it’s a long time before animals eat green grass again.

Heat Stress

In hot climates, or in years where there is abnormally high temperatures, cows can end up miscarrying due to heat stress.

In one case, reported on the Moocall Breedmanager App, German farmer Phillip Ellerbrock found a 40-45 day old embryo behind a cow.

This was after a prolonged period of 35C temperatures. Not only did this happen, but fields of grass and grain were dried up and burned by the sun.

hand holding a tiny cow embryo


Keep in mind what you’re putting in your cow’s body at breeding season – take environmental factors into account and make sure you keep an eye on the quality of pasture.

If it isn’t up to scratch, you need to supplement your cows with these vitamins, using things like mineral licks.

There are a number of ways you can prevent and alleviate Heat Stress and its effects on your herd. If they are out on pasture, ensure that they have an area of shade where they can stay cool if they need to. In some hot countries farmers dig cooling ponds.

Field with cattle on a sunny day seeking shade under a tree by moocall

If they are in housing, make sure you have a cooling system to keep the air temperature down. This will have the added effect during the winter of preventing disease.

Moocall HEAT

However, no matter what the weather, there is always a percentage of cattle who will have silent heats during breeding season.

For these, you cannot rely on visual observation and manual heat detection. Most so-called ‘silent heats’ are just farmers failing to see the signs of heat that exist.

Moocall HEAT, however, doesn’t have this problem.

Moocall HEAT collar used for heat detection

Because Moocall HEAT harnesses the unique ability of the bull, it will catch things that you miss. You don’t even need to be near your farm – you will get an SMS whenever the collar detects mounting activity.

It can greatly improve your AI effectiveness by giving you an exact time so you can inseminate when the time is right, and it works with stock bulls too.

Learn more about Moocall HEAT here: https://www.moocall.com/pages/moocall-heat-information

Young Hereford bull wearing a Moocall HEAT collar belonging to Pulham herefords