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A.I., a value-adding tool

published: March 16th 2007
by: Martha Hollida Garrett

It’s one of the oldest reproductive technologies available to beef producers, and is often considered the most valuable tool for adding value to a herd. Artificial insemination became popular and practical in the 1960’s and is still considered one of the top things a registered breeder or commercial breeder  in recent years can do to improve their herd and dollars generated.

Dr. Harlan Ritchie, distinguished professor of animal science Michigan State University,  says that artificial insemination provides the cow-calf producer an opportunity to use bulls possessing superior genetics. In addition AI offers an economically feasible means of increasing productivity over a wide range of traits.

AI is viewed as a tool to meet production and economic goals. It’s advantages include having access to  superior quality bulls at a relatively low cost, and having the ability to individually mate cows and strengthen weaknesses accordingly. Also AI sired calves almost always bring a premium as their genetics are in more demand. The number of commercial breeders now using AI is increasing each year and with synchronization it is now feasible.

Success with artificial insemination requires attention to detail in all areas of herd management and with spring breeding season just weeks away, its time for producers to evaluate their position and their cows’ readiness for breeding. The following material was condensed from presentation by Glenn Selk, extension specialist with Oklahoma State University.

One of the most important factors affecting the success of the program is the owner/manager’s attitude. He or she must totally desire to make AI work and instill this commitment into each link in the chain of management decision. The weakest link sets the level of success of the operation. Should any aspect of management become subpar, AI conception rates will be reduced, most likely to the extent it will cancel many of the benefits the technique offers.

Many managerial decisions relative to feeding, facilities, fences and corrals, equipment, sire selection, will be necessary. Both a sound health program and good nutrition are requirements of any breeding program but become an absolute essential ingredient for artificial insemination. In addition, more labor and skill are needed especially in the initial phases of the program.

Learning Artificial Insemination

Supervised instruction and guidance are essential because without adequate training, valuable AI equipment and semen could be seriously damaged. In order to ensure high fertility, frozen semen requires very special storage and handling techniques. Adequate training is also essential to minimize risk of injury to either a valuable animal or to yourself.

AI Training Schools are available from several semen suppliers. The objective of these schools is to teach the skills required to handle semen, inseminate cows, and manage a successful AI program. Three basic areas of instruction should be provided by AI schools including:

1. Insemination technique, developing through live animal practice, the ability to skillfully and accurately place semen at the proper location within the reproductive tract using sanitary and correct techniques.

2. Semen handling, developing through practice, the ability to properly handle, thaw and prepare semen for insemination, according to the recommendations of semen-producing organizations.

3. Reproductive management training in the importance of heat detection, herd health, and total herd management for the development and continued success of an AI program.

Heat Detection and Beef AI Programs

The most limiting factor in artificial insemination programs is the proper detection of cows or heifers in estrus. Estrus, or “heat”, is that period of time that occurs every 18-24 days in sexually mature, nonpregnant female cattle when they are receptive to mounting activity by bulls or other cows. In beef cattle operations where artificial insemination is the means of breeding the females, the herdsman must recognize and interpret a cow’s heat signals. Proper timing of the artificial insemination is necessary to accomplish a high percentage of conceptions in the cows that are bred artificially.

Considerable amounts of research have been conducted on the various factors contributing to the efficiency with which cows are detected in heat. When all is considered, one of the key factors is the skill of the human performing the heat detection. With an AI program, people assume the same responsibility as the bull for accurately detecting heat and the proper timing of insemination. Thus, the dilemma for the inseminator is determining which cows are in a “standing heat” and when that heat occurs.

A cow is fertile only when an egg has been released (or ovulated) from the ovary. This occurs about 10-14 hours after the period called “standing heat” ends. Because sperm need time in the cow’s reproductive tract before they are capable of fertilizing the egg, insemination should be made several hours before ovulation. This means that for the highest fertility, cows or heifers should be inseminated in the latter two-thirds of heat or within a few hours after having gone out of heat. This represents approximately 12-18 hours after the cow first comes in “standing heat.”

Heat Detection Efficiency

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 80-85 percent should be achievable.

The detection rate can be measured by the 24-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 24-day list. At the end of the 24-day period, the number of cows detected in heat is divided by the total number of cows eligible to have estrous cycles. If the producer observed 50 cows but only 15 were detected in heat in 24 days that is a 30% detection rate—not too good. If the producer finds 40 or more cows in heat during the 24-day test period for 80% or better detection rate, then a good AI program is possible.

A second method of self-evaluation of heat detection can be performed by keeping an accurate record of heat dates. The average interval (in days) between detected heats is divided into the “expected” interval or 21 days. For example, if the average interval between detected heats for all eligible cows is 25 days, then the detection efficiency would be computed at 21/25, or 84%.

Heat Detection

Requires Observation

The surest sign of estrus is that of a cow or heifer that permits other animals to mount her while she remains standing. This is the best sign of a cow’s fertile period. Therefore, the most productive means of determining which cows are in “standing heat” is to observe the cattle carefully for about 30 minutes at least twice per day. 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. There are several methods of this and the most popular these days is the CIDR® method of vaginal inserts. Computer generated heat checking systems are also popular, especially for larger breeders.

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. This fact alone is considered a major cause of heat detection inefficiency. Many of the cows that do have a “standing heat” from midnight to 6 a.m. can be observed as having “secondary” signs of heat at the time of normal heat-detection on the previous evening. 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),

(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 2-3 days after estrus has occurred and should be recorded in order to closely watch for heat in 17-21 days.

Timing of Artificial Insemination

Maximum fertility to artificial insemination occurs when cows are bred near the end of “standing heat.” Ovulation occurs about 12 hours after the end of standing heat. The 12-hour lead time allows the sperm cells to go through a process known as capacitation by the time the egg is released. Fertility decreases slightly when cows are bred a few hours on either side of this target, and decreased markedly when breeding occurs more than 12 hours away from the end of “standing

heat.” A guide that has proved to work well for timing AI is called the AM/PM rule. 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

Prior to breeding season breeders need to be evaluating their body scores on their cows, analyzing nutrition and making plans for a successful spring breeding season.

The missing or limiting ingredient in implementing a successful AI program is often management, facilities and labor.