Heat detection efficiency rate is defined as the percentage of eligible cows that are actually seen or detected in heat. Several methods of calculating the efficiency with which heat is detected are available. A detection rate of percent should be achievable. The detection rate can be measured by the Day Heat Detection Rate Test, which is a test that the producer can implement to self-evaluate the heat detection efficiency or inefficiency.
In order for cows to be included in the test, they should be eligible to have heat cycles, at least 50 days post-calving for beef cows; be free of reproductive disorders such as cystic ovaries, pyometra, or other reproductive tract infections; and be nonpregnant. In addition, cows must have adequate body condition to expect most of them to be cycling.
What producers are looking for is a group of cows that are most likely to display estrus in the next 24 days. Some of these cows will in fact be serviced during that interval, which will exclude them from the next day list. At the end of the day period, the number of cows detected in heat is divided by the total number of cows eligible to have estrous cycles.
A second method of self-evaluation of heat detection can be performed by keeping an accurate record of heat dates. The surest sign of estrus is that of a cow or heifer that permits other animals to mount her while she remains standing. More frequent observations may also be beneficial whenever it is practical. Estrous synchronization will aid in accurate heat detection and shorten the number of days that heat detection must be done. The best times of the day to observe cattle for heat detection are early in the morning and at the last daylight in the evening.
However, heat detection while cattle are eating at feed-bunks or hayracks is difficult because hungry cattle are often more interested in the feed than in each other. Table 1 from Cornell University researchers describes the percentage of cows showing signs of heat at different times of the day. By far the largest percentage of cows exhibit signs of estrus at the least convenient time of the day for accurate heat detection.
This fact alone is considered a major cause of heat detection inefficiency. The secondary signs of heat include 1 a willingness to mount other cows, even though neither cow may be willing to stand for the mount, 2 roughened tail head or mud on the rump, which is evidence that other animals have tried to mount her, 3 restlessness, which may be indicative of a cow about to exhibit heat cows in pre-heat may bawl more than usual, head-butt, pace the fence, sniff or lick other cattle and 4 clear stringy mucus discharge which may be hanging from the vulva or smeared on the pin-bones or rump of a cow about to have estrus or one already in estrus.
Bloody mucus often appears days after estrus has occurred and should be recorded in order to closely watch for heat in days.
Several aids to heat detection are available for producers with artificial insemination programs. This is a device similar to a ball-point pen that is strapped on the underneath side of the chin of an animal expected to mount cows or heifers in heat. The ink in the chin-ball marker leaves colorful streaks on the back or rump of a cow that has been mounted or was attempted to be mounted.
This device is glued to the rump just forward of the tailhead of cows suspected to be in heat in the near future. Prolonged pressure at least 3 seconds from the brisket or chest of mounting animals will turn the originally white detector to red. Using the heatmount detector will be more effective in those pastures with little or no low-hanging tree limbs, brush, or backrubbing devices since false readings can occur.
An economical heat detection aid is used at many U. The paint stick is available at many farm and livestock supply stores and comes in a variety of colors. Orange is often the color of choice, especially with producers who are color-blind.
The chalk or livestock paint is rubbed on the tail-head of cows to be heat detected. The chalk should be placed from the imaginary line between the hook or hip bones back to and including the corner where the tail begins its vertical descent.
Some producers choose to chalk in a narrow strip in summer months after shedding has occurred and wider bands on winter hair coats. Most tail-chalking veterans put the chalk in a strip two to three inches wide. The length is important because of the different contact points possible when the cow is mounted. In the spring, when cows are shedding, it is just about imperative that the area be curry-combed so the applicator will deposit chalk instead of just rub off winter hair.
Beef cattle producers can tail-chalk cows, at about 50 days after calving, while the cows are crowded in a long working chute or alley. Reading the chalk strip is not hard but does require close observation and some practice. When a cow is just coming into heat and is being ridden but will not stand, the chalk will be slightly smeared.
The cow should be watched to see if she does in fact allow other animals to mount her. The oil-based chalk is relatively rain-resistant and unlikely to be rubbed off in brush. After seven to ten days, it will take on a flaky, crusted appearance as it dries. Some AI technicians choose to re-chalk cows when the chalk becomes weathered and dried, but no signs of riding have been apparent. Occasionally, a cow will lick off the chalk. Usually, the obvious lick marks on the hair of the tail-head indicate that she had not been ridden.
The hour lead time allows the sperm cells to go through a process known as capacitation by the time the egg is released. At the end of the morning heat detection period, animals detected the prior evening are bred; at the end of the evening heat detection period, those observed that morning are bred.
In some situations, AI must be employed once-a-day wherein all animals detected in the prior 24 hours are bred. Some studies show little decrease in fertility when this approach is used. The quality of frozen semen when it arrives at your farm or ranch is determined by the bull and organization that processed it. But once it arrives, it is up to you to take proper steps to ensure its viability.
Frozen bull semen can be stored indefinitely, if it is maintained constantly at very low temperatures. The critical temperature is approximately degrees. The extent of damage depends upon how long the semen is exposed to the elevated temperatures. Although it is easy to maintain frozen semen at a safe temperature, it is also easy to destroy it in a few moments of carelessness. The semen storage tank is a large vacuum-sealed metal bottle with an extremely efficient insulation system.
Technical advances in design and construction have produced storage tanks with a liquid nitrogen holding time of six to nine months. Although semen storage tanks are well constructed, they still are susceptible to damage from mishandling.
Semen tanks should be kept in clean, dry, and well-ventilated areas. Avoid excessive movement of the tank. The inner chamber, which contains liquid nitrogen, is suspended from the outer shell by the neck tube. Any abnormal stress on the neck tube, caused by sudden jarring or an excessive swinging motion, can crack the tube. This results in vacuum loss from the outer chamber.
To increase holding time, keep the tank in a cool location away from direct sunlight. Avoiding drafts from furnaces and outside air also helps prevent excessive nitrogen evaporation. Developing the skill to thread the insemination rod through the cervix should not be the only objective. AI training programs should also emphasize the importance of sanitation and the perfection of skills to consistently identify the proper site of semen deposition and to accurately deposit the semen.
In addition, trainees should obtain a good understanding of reproductive anatomy and appreciate the essentials of a sound reproductive management program.
While artificial insemination proficiency of professional technicians is monitored by nonreturn rates calculated by the breeding organizations , the conception rate obtained by owner-inseminators is not monitored and routine retraining generally is not provided. The purpose of this fact sheet is to provide a review for those individuals already familiar with the AI technique, with special emphasis on reproductive anatomy, sanitation, and accuracy of semen deposition.
In the early days of AI there was controversy among researchers about the optimum site for semen deposition. A study conducted in Canada provided evidence that fertility was highest when semen was deposited in the uterine body. Researchers currently are reexamining insemination technique to determine the proper site of semen deposition.
Failure to understand the anatomical and functional relationships among the various tissues and organs of the reproductive system may lead to consistent insemination errors.
Most AI training schools use excised tracts to illustrate reproductive anatomy. Often the tracts are dissected to allow students to view the interior of the uterus.
This is a useful exercise; however, dissection can distort the relationship between various regions. Figure 1 is an illustration of the reproductive anatomy of the cow and a radiograph photograph of an X-ray of the cervical region and uterus. Radiography allows students to view the intact tract and simultaneously observe the interior of the uterine body and horns and, in many cases, the cervical canal.
Figure 1. Diagram side, or lateral, view of the reproductive anatomy of the cow and radiograph top, or dorsal, view of the cervix, uterine body, and uterine horns. The uterine body is the area between the internal cervical os and the internal uterine bifurcation, where the uterine horns begin to separate inside the reproductive tract. Obviously, there is not much room for error in placement of the insemination rod tip. While palpating the reproductive tract to find the landmarks for insemination, the inseminator usually obtains an idea of the overall size of the reproductive tract.
Some inseminators may have the impression that the larger the cervix or the longer the reproductive tract, the larger the uterine body.
This assumption is incorrect. Insemination errors can result from such misconceptions about size of the uterine body in relation to the overall size of the reproductive tract.
Critically evaluating the accuracy of insemination has been difficult. For many years, the dye method was used to evaluate the proficiency of professional technicians.
Excised reproductive tracts were inseminated with a biological dye in place of semen. In some cases, live cows were inseminated with dye and the tracts were examined immediately after slaughter.
The location of the dye within the tract indicated the site of semen deposition. Table 1 summarizes the results of dye inseminations in live cows and relates the results to the field performance of technicians to day nonreturn ratings. Nonreturn rate is an indirect measure of fertility. Technicians with a nonreturn rate greater than 78 percent achieved 86 percent of their dye depositions in the uterine body and they had no extrauterine inseminations.
Inseminations by technicians with nonreturn rates below 70 percent resulted in only 34 percent of the dye depositions in the uterine body and 31 percent extrauterine inseminations. It appears that accurate semen deposition is correlated with successful conception rates.
The dye method has some limitations. The location of the insemination rod tip cannot be determined, and manipulation of the reproductive tract during slaughter or dissection can distort the distribution of the dye. Researchers at The Pennsylvania State University have used radiography to evaluate insemination technique accuracy. This method allows the interior of the tract to be viewed without dissection and the location of the insemination rod to be easily seen.
Twenty professional technicians and twenty owner-inseminators were evaluated by this technique. Each participant inseminated twenty reproductive tracts. Two radiographs were evaluated for each insemination. The first was taken after insemination rod placement and the second after semen deposition.
Placement of the rod tip was assessed from the first radiograph and distribution of semen from the second. Analysis of radiographs of all inseminations indicated that only 39 percent of the rod tip placements were within the uterine body.
Placements in the cervix, right uterine horn, and left uterine horn were 25, 23, and 13 percent, respectively. Semen distribution, determined from the second radiograph, showed that 40 percent of the semen was located in the uterine body or equally distributed in both uterine horns.
The remaining 60 percent was located in the cervix or disproportionately in one uterine horn. Accurate distribution of semen was significantly related to proper placement of the insemination rod. Figures 2a and 2b illustrate correct rod tip placement and semen distribution. Figures 2c, 2d, 2e, and 2f illustrate examples of incorrect AI technique. Figure 2. Radiographs of excised cow reproductive tracts illustrating insemination rod tip placement left and distribution of radiopaque semen right following correct AI technique a, b and incorrect techniques c, d, e, and f.
National Library of Australia. Search the catalogue for collection items held by the National Library of Australia. The National Library Reading Rooms are now open at reduced hours. Find out more to plan your visit. Chemineau, P. Training manual on artificial insemination in sheep and goats. Request this item to view in the Library's reading rooms using your library card. To learn more about how to request items watch this short online video. You can view this on the NLA website.
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