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Fricke outlines five keys for reproductive success

Aug. 30, 2012 | 0 comments

Dairies that effectively turn the major keys to bovine reproduction open the door to business success.

It boils down to five key areas, Dr. Paul Fricke, University of Wisconsin Department of Dairy Science's reproductive specialist, said during the Aug. 12 Hoard's Dairyman Webinar hosted by Dr. Mike Hutjens, University of Illinois.

The reproductive performance of a dairy is determined by how rapidly the management system turns open cows into pregnant cows.

During his presentation, which was sponsored by Merck Animal Health, Fricke described ways to improve pregnancy rates with new breeding strategies and new ways to identify open cows, more aggressively rebreed cows, and better time artificial insemination (AI).

Key #1

Fricke's first key is to inseminate cows quickly after the end of the voluntary waiting period.

This used to be a major problem on dairies, with many cows going many days without being bred, he said, but that has changed with the common use of a synchronization protocol to set up cows for first post-partum breeding.

With an Ovsynch program, for example, a cow is given a GnRH injection seven days before prostaglandin F2a, followed by a second GnRH injection 56 hours later and then timed AI 16 hours later.

"The key with timed AI is you don't have to watch for estrous and that's really the benefit to a program like this," Fricke said. "One hundred percent of the cows that start this program will actually get inseminated. It's one way to drive the service rate in a herd."

A very effective way to get cows inseminated is to give two prostaglandin injections 14 days apart (Presynch) and breed cows that show estrus. Any cows that don't show estrus are enrolled in the Ovsynch program. About 50 percent of cows will typically be caught in estrus, he noted.

The question of whether farmers should or shouldn't be breeding their cows to estrus was recently researched at a 1,000-cow dairy using different treatments.

One treatment used the Presynch + Ovsynch protocol. An accelerometer was used to identify cows that showed estrus after the prostaglandin shots, and they were then inseminated. Cows not showing estrus moved through the Ovsynch program and were given a timed AI.

Another treatment used the identical program and timing, but cows that showed estrus after the second prostaglandin shot were not bred. All cows were simply allowed to go through the entire protocol.

The results were quite interesting, Fricke said. In the first treatment, 71 percent of the study cows were caught in estrus using the accelerometer. When bred to that estrus, the conception rate was about 30 percent, a level Fricke considers the cut off between okay and problems.

The remaining 29 percent of cows in that treatment group, meaning those that didn't show estrus and were enrolled in the Ovsynch program and had TAI, had a conception rate of 37 percent.

In the second treatment, the same percentage of cows showed estrus, but waiting to inseminate those cows pushed their conception rate up 10 percentage points.

"What you're looking at here is the presynchonization effect," Fricke explained. "Those cows that show estrus (after the prostaglandin shots) are perfectly set up to start the Ovsynch part of the program."

The cows that went through the program and had timed A.I. had a conception rate of 33 percent.

The research results set up a bit of a conundrum, Fricke admitted, considering cows in the first treatment group were bred at 62 days with an overall conception rate of 32 percent, while cows in the second treatment group were bred at 75 days with an overall 38 percent conception rate.

To help dairymen decide whether they should breed their cows earlier at lower conception rates or later at higher conception rates, a team lead by Dr. Victor Cabrera has developed an economic decision-making support system for selection of reproduction management systems, Fricke said.

A model, available for download on the web, can be found by goggling "Victor Cabrera at UW-Madison".

In comparing the economics of the two treatments, Fricke pointed out that the net present value in dollars per cow per day were identical. "This bears out what I have been saying for a long time - there is no one way to do reproduction on the farm," he observed.

Dairymen can purchase an accelerometer system, an "interesting" option for which Fricke calculated an amortized cost over eight years of less than three cents a day per cow on a 1,000-cow dairy.

Another newer technology is the Double Ovsynch schedule, he noted, which can really boost fertility rates for younger cows.

Key # 2

The second key to reproductive success is to inseminate cows at the correct time in relation to estrous or ovulation.

It breaks down to timing of the artificial insemination, AI efficiency, male fertility and female fertility, Fricke said. All four areas must be optimized to achieve high fertility.

Fricke does not believe in the long-used rule saying cows showing heat in the morning should be bred that evening and cows showing heat in the afternoon or evening should be bred the following morning. "For over five years now, I've been trying to make everybody forget this rule," he said.

Fricke points out that cows inseminated within 12 hours of estrus have the highest fertility. "My argument against waiting 12 hours is you don't know when that first standing event of estrus happened," he said. "The data says if you see a cow in heat, you can go ahead and breed her. It is impossible to breed a cow too early based on detection of estrus."

When the 100 people tuning into the webinar were asked how they detected estrous on their farms, the answers were 53 percent use visual detection, 27 percent use tail chalk, 26 percent used pedometers, and eight percent used accelerometers.

Accelerometer systems rely on a collar on the cow and a reader in the parlor to evaluate estrous activity. In researching how well they work, Fricke's data showed 71 percent of study cows were detected in estrous and 95 percent went on to ovulate.

The problem is the 29 percent of cows that were not detected in estrous, but were ovulating. The same results were found with the Heatmount detection system, Fricke pointed out: cows were not showing behavioral estrus, but were ovulating.

"What I've been telling people is you are never going to catch all your cows in heat with an accelerometer, but 70 percent can be caught in estrus and the remaining 30 percent will require some sort of synchronization," Fricke said.

He blames it on cow biology, not the device. "We have a lot of lactating dairy cows ovulating without showing estrous. They are not following the reproductive textbook," he quipped.

Cows need to be bred 8-12 hours before they ovulate. "The thing that's killing us is cow variation," Fricke said, with some cows inseminated too early and others too late. "You will breed about 70 percent of cows to estrus with an accelerometer system, but I'm afraid that you will breed those cows at a little bit lower conception rate."

In comparison, cows on an Ovsynch program have a very tight window of ovulation of 24-32 hours after the second injection of GnRH, with the greatest conception rate at 16 hours.

Key #3

The third key is to improve AI efficiency through optimum semen handling and inseminator technique.

An important question is how many straws of semen can be thawed out at a time. Studies show that the answer is only as many straws as the inseminator can get into cows within 15 minutes of thaw. "After that, we see a reduction in fertility," Fricke said.

The quality of the inseminator also has a big influence, with a 45 percent fertility success rate found for professional inseminators as a group versus 27 percent for herd inseminators as a group. "The studies are bad news for herd inseminators," Fricke said.

Success revolves around semen placement, which needs to hit the uterine body's small target of about one centimeter. "Who breeds your animals is a big deal," Fricke underlined.

Key #4

Identify non-pregnant cows early after an insemination, but not too early.

When Fricke questioned how his listeners identify non-pregnant cows on their farms, 40 percent used palpitation, 51 percent used ultrasound, and nine percent relied on blood test.

The practical application and benefit of an early non-pregnant diagnosis is to return those cows to AI service. "Doing that is a way to increase the AI service rate in your dairy," Fricke pointed out.

However, in research involving 1,116 cows, 68 percent were called pregnant because the actual embryo was visible on day 29. Another 29 percent were called pregnant based on uterine fluid and the presence of a corpus luteum (CL ).

The cows were rechecked at 74 days with interesting results, Fricke said. When a pregnancy diagnosis was based on a visible embryo, losses were only nine percent.

However, when a pregnancy diagnosis was based on fluid and corpus luteum and no embryo was visible, the losses were 28 percent. "The pregnancy was not viable," Fricke explained, so if pregnancy checks are done too early, it will drive up the pregnancy loss rate on the farm.

Checking cows for pregnancy too early is something Fricke has been warning dairymen about for years. In February of 2005, he co-authored an article for Hoard's Dairyman on the subject. "New technology must be implemented correctly or you can actually make things worse, rather than better," he pointed out.

Chemical pregnancy tests are now available, with three commercial assays developed to determine pregnancy status in lactating dairy cows 27 days after TAI. It takes about 36 hours from the sample collection to outcome, since the samples must be sent away for analysis, Fricke said.

The tests are quite accurate if done correctly, he noted, diagnosing 94.6 percent of tested animals correctly.

Key #5

Aggressively re-inseminate non-pregnant cows.

Currently, first breeding conception rates are "incredibly high" at 47 percent. The industry has come a long way in 15 years, Fricke added, thanks to the growing ability to manipulate reproductive biology to get very good fertility at first breeding..

With repeat breedings, conception rates fall to less than 32 percent. However, Fricke detailed a comparative study of synch/resynch timelines that showed resynch programs beginning on day 33 can offer fertility rates of 38 percent.

Another experiment questioning the appropriate timing of resynch showed it made no difference in the conception rate whether the resynch program started on day 32 or on day 39, as many herds in the Western U.S. do. That means day 32 is better from a pregnancy rate standpoint because it means a higher service rate, Fricke pointed out.

Seeking to improve fertility, the researchers also tried giving a setup injection of GnRH. "We know that cows that start this protocol with a CL have about 10 percent higher conception rates than cows that don't," Fricke explained.

They found the effect of the setup injection was statistically significant at about five percentage points.

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