Milk, motherhood and the dairy cow
In the 1990s, dairy farmers were seeing a troubling trend in their herds. As cows produced more milk, their reproductive performance declined.
This downward slope in reproduction, related to changes in the hormone metabolism of high-producing cows, spurred researchers into action. And CALS scientists found a solution — a reproductive synchronization system that could save Wisconsin dairy farmers more than $50 million each year.
'The development of these systems has been one of the greatest technological advances in dairy cattle reproduction since artificial insemination,' says Paul Fricke, a CALS professor of dairy science and a UW–Extension specialist. 'It is highly, highly significant.'
For the past 20 years, Fricke has been working on the synchronization systems with fellow dairy science professor Milo Wiltbank. The systems, called Ovsynch, consist of treatments with naturally occurring hormones and are based on Wiltbank's research into the basic biology of the cow reproductive cycle. The hormonal treatments synchronize the cycles so that farmers know when their cows are most likely to become pregnant.
Pregnancy rates in a herd are a product of two numbers: the service rate (the percentage of eligible cows that are inseminated) and the conception rate (the number of inseminated cows that become pregnant). Historically, farmers relied on visually recognizing when cows were in heat in order to time insemination—a tricky feat that often resulted in missed opportunities and low service rates.
'One of the biggest problems in dairy cattle reproduction is seeing the cows in heat,' says Fricke. 'If you can proactively control the reproductive cycle, you can inseminate cows without waiting for them to show heat.'
Removing the guesswork
Synchronization systems take the guesswork out of insemination, increasing service rates and pregnancy rates. Since the technology was first published in the mid-1990s, Fricke, Wiltbank and their colleagues have worked to optimize the systems. Researchers now see conception rates of more than 50 percent, and pregnancy rates of 30 percent or higher. Just 15 years ago, average conception and pregnancy rates were around 35 and 15 percent, respectively. A 30 percent pregnancy rate in herds producing high volumes of milk was unimaginable.
With impressive pregnancy rates and the safety of the system — the natural hormones used are short-lived and do not end up in food products—researchers and farmers alike are excited about further adoption of the technology. The payoff is substantial, considering the costs and benefits of breeding dairy cows, says Kent Weigel, professor and chair of the Department of Dairy Science.
'If we say that this technology will result in a 6 percent improvement in pregnancy rates, and we assume that it costs about $4 for each extra day that a cow is not pregnant, the technology could save Wisconsin dairy farmers about $58 million per year with just 50 percent of farmers using it,' explains Weigel.
This article originally appeared in Grow: Wisconsin's Magazine for Life Sciences.