Clintonville — Dr. Paul Fricke, UW-Madison dairy specialist, shared some of his latest research on ways to improve conception rates among high-producing dairy cows during a recent presentation at the Fox Valley Technical College Regional Center.
The presentation was part of the Cow College series of education programs offered annually to producers and other industry professionals by the UW-Extension agricultural educators in Waupaca, Shawano and Outagamie counties.
“We can really now get higher pregnancy rates in herds of high-producing lactating dairy cows than we ever could before, and it’s really because of the development of new technologies,” said Fricke. “We can increase the fertility of these dairy cows as well as increase service rates.”
Comparing heifers to lactating dairy cows, he noted that lactating dairy cows are generally thought of as being less fertile.
“Conception rates in cows are generally less than 50 percent," Fricke said, "while higher in heifers, and pregnancy loses are relatively high in cows, yet lower in heifers.
“A lot of people have made the argument that we have genetically selected against fertility in high-producing lactating dairy cows, but I don’t think this is a genetic issue; it has to do with the physiology of the high-producing dairy cow."
Fricke said that while hormonal synchronization protocols have been incorporated into reproductive management programs, a deeper understanding of the physiology underlying the Ovsynch protocol has enabled a dramatic increase in fertility to timed artificial insemination (TAI).
“Progesterone (P4) is the most biologically active progestogen in cattle, and is primarily produced and secreted into circulation by the corpus luteum (CL) during the estrous cycle, and the placenta during pregnancy,” Fricke explained.
“What’s happening with these lactating dairy cows is that while they’re giving more milk we’re seeing sub-normal levels of progesterone, because the highest producing dairy cows are better able to convert feed into milk,” he said. “When a cow eats a lot of feed she increases her visceral blood flow that drains from the gut directly to the liver, which is very efficient at clearing the blood of these steroids estrogen and progesterone.”
According to Fricke, the goal of the latest fertility programs is to overcome the lower-then-normal levels of progesterone and estrogen.
“When I look at a farm’s reproductive management program, the first question I ask is: How and when are cows submitted for their first insemination?
“In order to get a cow pregnant we have to get semen in her, but we know that not every cow gets pregnant on the first try, so the second question is: How and when are non pregnant cows identified and re-inseminated?”
Measuring a dairy herd’s fertility rate is is done by determining how rapidly the management program turns open cows into pregnant cows, he related.
“We want to measure the 21-day pregnancy rate, which is the proportion of eligible cows that get pregnant in a given 21-day period,” Fricke emphasized. “This is dependent on the service rate with which we can put semen in the cow, and the fertility of the cows we breed, which is their pregnancy rate per insemination.”
He suggested that producers get semen in their cows before they are 100 days in milk. Watching for heat and hoping for the best is not a formula for success, according to Fricke, because people aren’t always around to observe this.
In addition to the people problem, his research also has also revealed more about the cow problem. “As the cow’s milk production increases, her estrus period decreases because her increased feed intake metabolizes estrogen in the blood quicker,” he explained.
Solving the cow fertility problem took a major step forward with the development of the Ovsynch protocol, according to Fricke. “It’s a powerful tool to put semen into cows,” he said. “Two treatments of prostaglandin 14 days apart should get cows to come into heat about three to four days later, and about 10 days after that you should hit day six or seven of the estrus cycle.”
However, that treatment is not going to help about a quarter of the herd that contains non cycling cows, and breeding high-producing cows to estrus does not maximize fertility, according to Fricke.
Getting cows to respond to the Presynch-Ovsynch protocol, can produce high fertility in these lactating cows, according to Fricke.
“It’s very clear that if there’s a little bit of progesterone around fertility is terrible because it inhibits semen transport,” he added.
Double Ovsynch protocol
“With a double Ovsynch program, that combines GnRH with prostaglandin, which is used to synchronize cows, you deal with the an-ovular cows by getting them out of that condition,” he said. “We’ll get about 90 percent of the cows to ovulate, which means 90 percent of the cows start Ovsynch on day 7.”
He said older cows really responded to double Ovsynch (DO). “With one treatment of prostaglandin 36 percent of them ovulated, and 45 percent when that second prostaglandin is added 24 hours later. This has a huge effect because older cows have more problems with luteum regression, and it also resulted in 23 percent more pregnancies,” Fricke stressed.
On this protocol, not only do you get semen into cows quickly, you get really high fertility if your cows are healthy. It’s the highest fertility we can get on the first insemination. Almost all the cows are inseminated within 7 days of the voluntary waiting period.
Fricke recommends using this protocol for first breeding and using their heat-detection systems to catch cows that come back into heat.
Sharing his research, Fricke said, “We set up cows on a double Ovsynch program for the first breeding at 77 days in milk, and we used the two prostaglandin program. We found conception rates at 50 percent, which compares to conception rates of only 30-35 percent 10 years ago.
An aggressive reproductive management strategy that incorporates these concepts significantly increases the 21-day pregnancy rate in high-producing dairy herds.