Heat Signs in Cattle

Successful heat detection is a time-consuming exercise and requires trained personnel considering its limited time frame and impact on the success of production in farms. Cows and heifers on heat will exhibit observable signs or behaviours that vary across three key phases categorized as coming to heat, standing heat, and going out of heat.

The observer needs to differentiate the stages to evaluate the right timing for the success of any breeding attempts during the standing heat phase. Visual observation is used to identify females on heat with the surest sign and recommended breeding time noted to be when heifers or cows remain standing when mounted by others in the standing heat period.

The standing heat period is characterized by physical mounting and happens 12-18 hours on the onset of heat making timely visual observation key to heat detection. Once ovulation happens towards the end of standing heat, the cow is fertile up to 6-10 hours providing a limited time frame for successful breeding.

The following are the key signs observed in heat detection in cows.

Coming to Heat

Mounting Behavior

One of the most noticeable signs is mounting other cows. When a cow is in heat, she may mount other cows or allow herself to be mounted by other cows. This behaviour is an attempt to show sexual receptivity. In the coming to heat phase, the cow or heifer will mount or allow others to mount them but will move away.

Mucus Discharge

A cow in heat may have a clear, sticky mucus discharge from her vulva. This discharge is a result of hormonal changes and is often seen as a reliable indicator of estrus.

Sharp Decrease in Milk Production and Appetite

 In some cases, a cow in heat may exhibit a temporary decrease in milk production, changes in milk composition, and reduced appetite. However, these signs are not always reliable and can vary among individual cows.

Attention from Other Cows

Other cows in the herd may show interest in a cow in heat, sniffing or licking her vulva or engaging in mounting behaviour towards her.

Standing Heat

Allows Mounting Behavior

When a cow is in standing heat, she may ride other cows and will allow herself to be mounted by other cows without moving away. They stand still and will not evade the mounting marking the onset of the standing heat phase crucial in breeding activities.

Swollen and Reddened Vulva

The vulva of a cow in heat may appear swollen, moist, and reddened due to increased blood flow in the reproductive organs.

Increased Activity

Cows in heat tend to be more active and may engage in increased playfulness or roughhousing with other cows. They may kick up their hind legs, run, jump, or exhibit a generally higher level of energy.

Restlessness and Agitation

Cows in heat often display restlessness and agitation. They may walk or pace more than usual, vocalize more frequently, and exhibit heightened activity levels. They may also be seen sniffing and investigating other cows.

Going out of heat

Avoids Being Mounted

When a cow is going out of heat, she attempts to mount other cows but will move away and not stand to be mounted.

Increased Attention on Other Cows

When going out of the heat, the cow will show interest in other cows by sniffing or smelling them.

Gradual Resumption of Normal Behaviour and Production

As a cow is going out of heat, their normal behaviour resumes. This may include regaingin of appeittie or production. The restleness and aggitation is also reduced as they go back to their normal calm behaviour as it compared to the the onset and standing heat stages.

It is important to note that the intensity and duration of these signs can vary among cows and some will show subtle or fewer signs of heat. Dairy farmers often use visual observation, activity monitoring systems, or other technologies to aid in detecting heat and optimizing the timing of artificial insemination or mating for successful breeding.