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Beef Workshop Anticipates Next Calving Season

11/9/2013 7:00 AM
By Michelle Kunjappu Reporter

NOTTINGHAM, Pa. — There’s a certain satisfaction that doesn’t get old in watching a healthy 80-pound calf take its first steps.

Many beef producers know not only that feeling of satisfaction but also the careful planning and management that lead up to that moment.

Recently, a Penn State Extension beef reproduction workshop at Herr Angus in Nottingham drew nearly 50 people to hear how to get those healthy calves.

Pete Hamming, Genex Cooperative/CRI area marketing manager, led a session titled “AI Technique and Proper Semen Handling” during the Nov. 2 workshop.

Reproduction is “a multiplication problem, not addition or subtraction,” he said. Nutrition, stress, and semen handling are equal parts of the equation.

For example, “if you get your semen handling 80 percent right and you control nutrition 70 percent right and you control stress 80 percent correctly, that’s about a 40 percent conception rate,” he said.

Hamming then gave a checklist on controlling the semen handling aspect of the equation, first expanding on what exactly is inside a straw.

Bulls give approximately 6 billion to 10 billion sperm per collection, yielding 400 to 500 breeding straws with about 15 million to 25 million sperm per unit, according to Hamming.

Besides that, each straw has glycerol, a cryptoprotectant, which allows the sperm to survive the freezing and thawing process and still be capable of fertilization.

Every straw also contains an antibiotic to control microorganisms that could infect the cow. Lastly, each straw contains an extender such as egg yolk (most often used) or milk, which protects the sperm from cold shock during freezing and provides nourishment for the sperm.

Proper straw handling starts with having a tweezer handy to pull the straws from the tank, since the temperature change from fingers touching the other straws in the goblet will damage them.

The time the straw is pulled until the cow is bred should be no more than 15 minutes, Hamming said.

If the straws are to be thawed in a water bath, the temperature should be between 90 and 95 degrees to thaw yet not overheat the contents. The straw should be in the water bath for a minimum of 45 seconds.

Another threat to sperm viability is direct sunlight, so Hamming recommends setting up shade to work under. Also, to keep the temperature of the straw’s surroundings somewhat the same, the gun should be warmed so the straw and its fragile contents don’t undergo a quick drop in temperature.

When the straw is pulled from the water bath, it needs to be wiped off since water is a “mortal enemy” of semen, and water in the gun will kill it as it comes out of the straw, he said.

Synchronization

Megan Hain, a field service veterinarian from the University of Pennsylvania at New Bolton Center, gave a seminar on synchronization techniques during the workshop.

Synchronization of heat is, simply put, manipulating the estrous cycle of cows or heifers so they can be bred at approximately the same time and ultimately calve at the same time.

First of all, however, “reproduction is a luxury,” Hain said. “The cow will not be ready to breed if the nutrition is not there.”

She further discussed the fact that producers need to have a sufficient labor force, proper facilities and 100 percent commitment to the synchronization program “or you’ll throw money away” on the products used on the animals.

She recommended working out the kinks of a new synchronization program on a smaller group of animals, such as a farm’s first-calf heifers, for example, “to give yourself a learning curve” before introducing the program to the herd at large.

Embryo Transfer

Since a cow may produce eight to 10 calves in her lifetime, dairy and beef producers long ago started looking for a way to increase a genetically valuable cow’s ability to produce more calves.

Enter the in vivo and in vitro processes.

According to veterinarian Jim Evans of Genetic Visions, life for a calf can begin in vivo (Latin for “within the living”) or in vitro (Latin for “in glass,” such as in a test tube).

One way to get more than one calf a year from a cow is through flushing her, which entails stimulating ovulation (called superovulation) so that more than one egg at a time matures and can be harvested.

Every 21 days, the average cow’s follicles release eggs. One of these eggs will eventually mature and dominate, while the others regress. A cow slated for flushing will receive hormones to help the other eggs also mature.

“We’re not touching any eggs that wouldn’t naturally die or go on anyway,” Evans said.

About a week after breeding, the cow is flushed. During this procedure, solution washes into her ovaries and is drained into a tube that transports the embryos outside into a container. Then those embryos are frozen and later will be be placed in a recipient cow.

In the meantime, the recipients should be on a cycle that is seven days past ovulation to receive the embryos.

“The uterus is a very dynamic organ, and it changes every day,” Evans said.

Consequently, the uterus needs to be at the same point in a cow’s cycle to receive the embryo for the best chance of pregnancy.

On the other hand, during the in vitro process hormones stimulate follicles to produce several oocytes, which will develop into eggs. They are then suctioned out, fertilized by injection and placed in an incubator for six or seven days before they are checked for viability and are ready to be placed into recipient cows.

Understandably, the process isn’t a slam dunk surety.

According to Evans, flushing checks in with a failure rate of 28 percent (a failure is a yield of one good embryo or none). In vitro chalks up a failure rate of 15 to 20 percent.

Of the successful flushes, the in vivo technique may yield seven good embryos per collection and in vitro about five eggs. The in vivo technique checks in with a 75 percent pregnancy rate and in vitro a 65 percent pregnancy rate.

Cows can be flushed at 30 to 60 day intervals. With in vitro collection, eggs can be collected every two weeks.

Although this process may seem time intensive, the results are radically increased numbers of genetically superior calves added to the herd.

In other sessions, Julie Ellison, Purina Animal Nutrition sales specialist, discussed “Feeding the Cow Herd for Good Reproductive Performance” and Cheryl Fairbairn, Penn State animal science educator, spoke about “The Frustrations of Heat Detection and How to Avoid Them.”

Evans also spoke on “Managing the Cow and Bull for Improved Fertility.”


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