When married UW professors Jimena Laporta PhD’14 and Francisco Peñagaricano MS’14, PhD’14 left Uruguay for Wisconsin, they traded one cattle-crazed community for another. Uruguay boasts the world’s highest number of cattle per capita at nearly four beef cows for every one person. (The U.S. has just 0.28, and Wisconsin alone has 0.58.) But what Wisconsin lacks in abundance of cattle per person, it makes up for tenfold in innovation and influence. At the Dairyland’s flagship university, Laporta and Peñagaricano are enhancing the state’s namesake industry and improving the lives of cattle and their caretakers, wherever in the world they roam.
From the UW’s Dairy Cattle Center and the Arlington Agricultural Research Station to local farms and international conferences, Peñagaricano’s research is helping breed more energy-efficient and resilient cows, while Laporta’s research keeps them happy, healthy, and productive for generations to come.
Folks familiar with the dairy industry may know that recent years have seen record highs in milk production in Wisconsin. In fact, today’s dairy cow produces nearly twice as much milk as a dairy cow produced 40 years ago. But those numbers aren’t the only ones on the rise: Wisconsin summers are getting hotter and longer, putting the Dairyland’s herds at a higher risk of heat stress, and putting the dairy industry’s upward trends in jeopardy.
Luckily, the Laporta Lab at UW–Madison knows that happy, productive cows require more than feed and green pastures. Jimena Laporta PhD’14 is an associate professor of lactation physiology in the Department of Animal and Dairy Sciences in the UW’s College of Agricultural and Life Sciences. Her research focuses on optimizing the milk-production capacity of dairy cows by studying the influences of nutrition and the environment on their prenatal and early-life development, with special attention paid to the implications of heat stress.
“Heat stress” describes the adverse effects of increased core body temperature resulting from overwhelm of the body’s cooling mechanisms. In humans, this is referred to as “heat stroke” and is considered the most severe form of heat illness. The average human is most at-risk for heat stroke as temperatures near 88 degrees Fahrenheit. Cattle, however, begin to experience heat stress when temperatures reach 70 degrees Fahrenheit — what a human Wisconsin resident might consider a comfortable late-spring or early-summer day.
“A mature cow [weighs around] 1,600 pounds, and they have a rumen that generates a lot of heat,” Laporta says. “Making milk is an energetically demanding process, so [cows’] temperature thresholds are very different [than humans’].”
And as human Wisconsin residents know, summer temperatures don’t peak at 70 degrees. According to the Wisconsin State Climatology Office, Wisconsin’s average summer highs were 75–85 degrees Fahrenheit between 1991 and 2020. Looking ahead, the Wisconsin Initiative on Climate Change Impacts predicts that extreme-heat days (exceeding 90 degrees Fahrenheit) will triple and that evenings 70 degrees and warmer will quadruple by 2050.
This spells not only extreme discomfort for dairy cattle but also long-term consequences for the dairy industry. By collecting samples of blood, tissue, and milk from cows at the Dairy Cattle Center and the Arlington Agricultural Research Station, the Laporta Lab has found that on top of negatively impacting overall animal welfare, heat stress can reduce milk production and quality in both lactating and nonlactating cows by up to 30 percent.
Nonlactating “dry” cows include pregnant cows in their third trimesters as well as heifers, young female cows who have not yet produced their first offspring. These dry cows have historically been overlooked in studies on bovine heat stress, but they’re of particular interest to Laporta. As a lactation physiologist, she is especially interested in the development of the mammary gland, or udders, before the cow reaches milk-producing age (two years old).
“We know that heat stress impacts cows that are making milk because you can see it in the farmer’s pocket in the reduction in milk,” Laporta says. “The problem with nonlactating or younger animals is that you don’t see it right away, so it’s long-term effects are going to come later on.”
According to her research, exposure to heat stress both in-utero and during a heifer’s preweaned phase can lead to compromised immune systems, infertility, stunted mammary-gland growth, and reduced future milk production. These effects can also be passed down through generations.
In short, cooling cows — especially nonlactating members of the herd — is increasingly important to the continued success of dairy farmers everywhere. Luckily, where there are cows, there are collaborators: Laporta works with producers as far as France and as local as Wisconsin to share her lab’s findings on heat-abatement strategies and to hear directly from farmers about the challenges facing their herds.
“Their input really guides us to ask different questions and research different areas … I always come back with new ideas,” Laporta says. “It’s [also] great to hear from them because some of them approach you and they say, ‘I changed the management of my dry cows,’ or ‘I'm doing this with my calves because [of what you said].’ When you see that, you can sense firsthand that you're having an impact.”
When Francisco Peñagaricano MS’14, PhD’14 reflects on what first drew him to the study of genetics, he thinks of Mendel’s Laws of Inheritance. He remembers being fascinated by the ways in which the alleles of two gametes sorted neatly into genotypes in a grid, revealing the phenotypic possibilities.
As an associate professor of quantitative genomics in the Department of Animal and Dairy Sciences in the UW’s College of Agricultural and Life Sciences, Peñagaricano seems to have inherited that neat, categorized quality himself as he summarizes the questions his lab seeks to answer and the implications of those answers on the dairy industry.
In the Peñagaricano Lab, students work to understand the genetic architecture of cows’ economically relevant traits: those that prove beneficial to a profitable dairy. These traits include feed efficiency — producing the same amount of milk on a smaller amount of feed — reduced methane emissions from bovine belching, and resilience.
But what does all of this have to do with the price of milk? According to Peñagaricano, just about everything.
“Our goal is to address the concern of the society, and without [question], this society is very concerned about dairy farming,” he says, “about the impact that dairy farming has on climate change and global warming, the impact that dairy farming has on soil and water quality, the impact that dairy farming has on animal welfare, [and] the use of pharmacological interventions and impact on food safety.”
Through a study funded by the Greener Cattle Initiative, Peñagaricano and his lab are partnering with three other land-grant universities, the USDA, and the Center for Dairy Cattle Breeding to address these concerns by developing genetic and management tools for mitigating methane emissions in dairy cows. Presently, no tools exist with which dairy farmers can identify, select, and breed dairy cows for lower methane emissions, but there are certainly incentives for doing so: in addition to reducing the amount of the greenhouse gas emitted by the dairy industry, such a tool would allow for selective breeding of a more energy-efficient and cost-effective cow.
“You can think about the production of this gas [in the rumen] as a loss of energy … that could end up in more milk production or more growth,” Peñagaricano says. “That means if you reduce methane emissions, that energy probably will be captured by the animal in a different, more productive way.”
The Peñagaricano Lab collects data on feed intake and methane emissions at the Arlington and Marshfield Agricultural Research Stations using GreenFeed systems. These systems use alfalfa pellets to incentivize a cow to visit, then vacuum the air during the visit to measure methane output. They also measure body weight to track productivity and feed efficiency.
The project team also hopes to build their predictive tool for methane emissions based on an existing, routine process in dairy farming: milk testing. American farmers are required to test each cow’s milk once a month for levels of fat, protein, lactose, and somatic cell counts; Peñagaricano hopes to correlate this data to a cow’s methane production.
Another phenotypic (related to observable traits) approach the lab has taken to predicting methane production is to better understand the function and composition of the rumen, the stomach compartment in which methane is produced. To avoid the invasive sampling of the rumen itself, Peñagaricano’s lab has explored alternative methods of studying it via samples of related and more accessible microbiomes.
The team is only a year and a half into their study, but their data are already promising: they have been able to confirm the heritability of methane-emission traits — which are “at least as heritable as milk production, or even more” — indicating that methane-emission can be addressed through selective breeding.
As for using milk testing to predict methane production, the team has recorded strong correlations between their predictions and observations, suggesting the viability of this method going forward and in developing predictive tools. Finally, in the nearly 700 fecal samples they’ve analyzed, the team has recorded strong correlations between methane production and organisms present in the fecal samples, confirming the suitability of fecal samples as proxies of the rumen microbiome.
Do these early results point to a methane-free future of bovine belches? Unlikely, Peñagaricano says. But eradication was never the goal. Like everything from lightbulbs to phone batteries, the future of dairy lies in its efficiency.
“The cow today probably is more efficient than the cow of 50 years ago, because the cow today [is] eating more, but not twice as much … [and] she's producing more than twice,” Peñagaricano says. “But [there] is still room for a lot of improvement.”
Photos courtesy of Jimena Laporta and Nguyen Tran (Dairy Innovation Hub).
