What is heat in cattle and why is it important?
The heat or estrous cycle is the time when the cows become sexually receptive and they are ready to mate and exhibit sexual behaviour. The importance of detecting heat in cattle is not only for the timely artificial insemination but also to avoid the economic losses that the dairy farmer will have to bear due to extended calving interval and wastage of semen. Thus, detection of heat in cows becomes critical in the reproductive health management of the dairy animals.
Primary signs of heat in cattle:
Look for primary signs such as cows allowing to be mounted, this is a sign of standing heat where the animal is going through an intensive period of the estrous cycle and does not move away when mounted by the other animals.
The cattle come in the heat after every 21 days of the estrous cycle, but it may occur anywhere between 18 to 24 days. The standing heat lasts for a duration ranging from 6-30 hours, with the average duration of 15-18 hours.
Secondary signs of heat in cattle:
The secondary signs are not related to the ovulation and usually occur during, before, or after the standing heat period and the signs to look for include:
- Mucus discharge which occurs due to high levels of estrogen,
- Swelling of the vulva and the reddening of its interior,
- Excessive bellowing and restlessness,
- Sniffing of genitalia by other cattle is more frequent,
- Chin resting and back rubbing before mounting to check receptivity,
- Ruffled tailhead due to being ridden etc,
Testing the milk:
The hormone levels are high in the body and the milk produced during the entire period except for the peak of the estrous cycle or standing heat period when the cattle are ready to be served. So, using the milk progesterone test will help in reducing the false detection of heat and help in timely artificial insemination.
The dairy producers should ensure that these signs of heat should be extensively checked for and timely artificial insemination should be done. This is important for getting one calf every year and avoiding economic losses due to extended open periods. The cattle should be provided with an adequate dry period before the next lactation period.