Heat Detection in Beef Cattle
- [Instructor] In this presentation, we'll cover the basics of accurate heat detection in cattle.
The presentation was compiled by Cheryl Fairbairn, Penn State extension educator on the extension livestock team.
Cheryl's based out of Chester County.
Using superior sires for artificial insemination is the easiest way to push a herd forward genetically.
But there are many steps on the road to successful artificial insemination, often referred to as simply AI.
An accurate heat detection is one crucial step.
The fertility of the cow and the bull are obvious factors that affects heat detection.
The cow herself plays a major role in the ability to detect heat.
For example, is she reproductively sound?
Does she have feet problems or leg problems and she won't stand to be ridden?
Is she the boss cow and won't allow other cattle to ride her?
Does she show silent heats, or are you just missing her signs of heat?
She may be short cycling, or cycling longer than 21 days.
And all of these factors can aid in or disrupt your ability to catch her in heat.
People and the environment also play a major role in heat detection.
Accurate heat detection is more than just driving by the cows quickly as one heads off to work.
In order to get the job done, you have to spend enough time watching for heat, walking out among the cows and checking heats more than once a day.
The environment can affect heat detection as well.
If it's sweltering hot or raining or snowing, and the cows are standing on slippery concrete or maybe even rocks that give them no incentive to ride, heat detection will also be adversely affected in these scenarios.
The cows have to be in good shape, receiving enough adequate nutrition from pasture or other feeds in order to be cycling well.
Again, all of these things affect the cow's ability to cycle, and incentive to be ridden.
The first step in accurate heat detection is to understand the basics of the estrous cycle.
Understanding the estrous cycle will assist you in understanding how heat signs fit with other behavioral signs throughout the cycle, so that you can better detect true heats.
It will also help you understand the hormones given, and the response by the cow when using different synchronization techniques.
During the cycle, gonadotropin releasing hormone, or GNRH, is released from the hypothalamus in the brain, which stimulates the release of follicle stimulating hormone, or FSH, and the luteinizing hormone, LH from the anterior pituitary.
FSH stimulates the recruitment and development of follicles on the ovary.
When a follicle becomes large enough and near ready to ovulate, it starts to produce copious amounts of estradiol, which cause the typical behaviors we associate with heat, such as standing heat, vaginal discharge, increased activity, bowling or riding, and those types of activities.
When follicle is fully developed, the is a surge of LH released from the anterior pituitary, which causes the follicle to ovulate and release the egg.
The corpus luteum, or CL, is then formed at the site of ovulation.
The CL then produces progesterone which acts on the uterus to help prepare it for pregnancy.
The CL stays intact until about 16 to 21 days, when, at that time, if there is no pregnancy, the uterus releases a hormone called prostaglandin, which breaks down the CL, and the heat cycle starts all over again.
As stated earlier, the estrogen produced by the large follicle is what causes heat associated behaviors.
However, at this point, the follicle has not yet ovulated, so breeding would not be beneficial at this time.
In fact, the ovulation event occurs approximately 25 to 32 hours after the cow first starts showing standing heat.
And it takes approximately six hours in the uterus for sperm to undergo a process called capacitation, where they become capable of fertilizing the egg.
They then remain fertile and viable in the uterus for approximately 18 to 24 hours.
The fertile life of the egg, however, is much shorter, at only around 10 to 12 hours.
The egg is at its most fertile immediately following ovulation, so it is important that the semen be at the site of fertilization in the oviduct and ready to go at that time.
Due to all of the these factors, the optimum time to breed is the last half of standing heat, or about 12 hours after the cow is first seen standing.
This gives the sperm enough time to undergo capacitation, and reach the site of fertilization in the oviduct when the egg is most fertile.
If your heat detection is not accurate, insemination will not occur at the optimal time, and failure can result.
This is why it's so important to be able to identify standing heat and the other signs of estrus, so your breeding times can be optimized to reach their maximum potential.
The secondary signs of heat can vary in duration and intensity.
They can happen before or after standing heat, and have no specific relation to the time of ovulation.
Other signs of heat include increased nervousness, mounting of other cows while refusing to be mounted themselves, a swollen vulva or excess of licking or other cows, are often general signs of estrus.
Once the cow stands to be mounted, this is the best sign that the cow is in heat or will be ready to breed.
Clear mucous discharge will often accompany this behavior.
However, this may not always be the case.
Sometimes you will see clear mucous discharge without standing, so this alone should not be utilized to determine heat.
If you see dried mucous on the tail, or a bloody discharge with a roughened tail head, you have missed the critical time to breed, and should record that the cow was in heat a few days before this sighting, so you can watch her closely for the next signs.
The timing of service is very critical in successful AI programs.
The objective is to have viable sperm available in the tract, waiting for the arrival of the freshly ovulated oocyte, or egg.
Timing the service depends on the accuracy of heat detection.
If you miss a time and then find a cow in heat, you have no way of knowing if it was her first time in heat, or if she was already in heat for several hours.
If a good heat detection system is in place, then an AM, PM rule should be followed for insemination.
In other words, if you see cows in heat, read them 12 hours later.
If heat detection is irregular, then a good rule of thumb is to inseminate them immediately after the observation of standing heat.
Some work that was done at Penn State showed that you will have more cows bred by employing this system of heat detection, if heat detection is not optimal.
The absolute best results will occur if you can check heats two to three times a day, and utilize the AM, PM rule.
The number of herd mates can influence your heat detection success as well.
Small numbers of cows can be very challenging to detect heat in.
If a pecking order is established, some cows will never be ridden, even if they are in heat, and some cows will show zero interest in being ridden.
The boss cow may not let anyone ride her, for example.
But, the more herd mates, the more likely heat will be shown.
Bull calves running alongside cows may also aid in heat detection by riding or attempting to ride cows as well.
The number of herd mates in proestrus and estrus simultaneously will increase the number of mounts per cow in heat, and makes detection much easier.
Synchronizing your cows with CIDRs, or another program, may also aid in your ability to accurately detect heat because more cows will cycle together.
If you irregularly observe heat or don't have the ability to synchronize, there are a variety of heat detection aids on the market.
The Kamar heat detector is a pressure-sensitive mount detector that changes from white to red with pressure.
Three minutes of pressure is required to detect standing heat.
The patch is to be glued on the back between the pin bones and the hip bones.
The tag can be coded with the cow's number in case it's knocked off, and markers can be used to color-code for different situations, such as problem cows, different cycles, etc.
Another pressure sensitive mount detector are the Estrus Alert patches.
Patches come in different colors, so you can use various colors to determine different events, like pre-breeding cycling, breeding heat, re-check or confirmed pregnant.
Adhesive is already on the patch, so there's no need to add glue.
For the adhesive to work well, the patches must be near human body temperature, so keep it in your shirt pocket before applying in cool weather.
If you're applying many patches, you can consider keeping the patches warm in a cooler with a hot water bottle.
When cows are mounted, the surface of the patch is rubbed off, revealing color.
Additional mounting showed the color more vibrantly, such that you can usually distinguish between a branch rub and an actual mount.
Tail chalk is also an activity indicator.
It indicates whether or not some sort of riding has occurred, but it is non-specific.
If the tail head is ruffed up and the chalk is gone, there may be heat activity occurring.
MAC Tail Paint is usually an oil-based paint that comes in four colors.
Detect-Her Tail Paint is a combination of latex paint and adhesive, and contains bitter-guard, so that cattle can't just lick it off.
If you ask yourself, in this picture, which cow is in heat, you should respond the cow with no tail paint is the cow in heat, because she has stood to be ridden.
If your heat detection is perfect and the cow still doesn't breed, there are sometimes things that are beyond your control.
For example, does the cow have reproductive issues and is not able to breed?
Did the inseminator not handle the semen correctly, or place it in the wrong spot in the tract?
Did the cow get worked up as you tried to work her through a chute system that maybe was inferior?
Was the weather too hot or too cold?
Heats may not be shown if cows are lazy and decide it's too hot to ride.
In addition, some research suggests that heats may affect conception rates.
If the cows are too fat or too thin, this can also cause reproductive issues.
If she does not conceive after several attempts, she may be reproductively unsound, and will need to be culled.
In summary, requirements for accurate and successful heat detection include consistent time for heat detection each and every day.
Detection can occur at any time of the day or night, but it's most successful if you can check in the early morning hours and again in the early evening, and, if possible, later that same evening.
Drive-by heat detection, or every other day looks, will not lead to success.
You need to check cows several days before a heat detection date, and several days after a heat date, in case a cow decides to short cycle or carry the cycle just a little bit longer.
Successful and accurate heat detection takes knowledge of the estrus cycle, recognition of heat, and good records.
Records should include who showed heat and when, who is due back in heat, who you think may have been in heat, who is cycling every 21 days, or 19 days, or 23 days, and who are the ones needing to be re-bred.
Successful AI programs take time and patience.
But remember, if you can run a successful program, your efforts will pay dividends.
Frequently Asked Questions