Jimena Laporta Sanchis wants to help dairy cows beat the heat. She’s an associate professor of lactation physiology at the University of Wisconsin-Department of Animal and Dairy Sciences.
A 70-degree day is welcome news to most Wisconsinites, she said, but it’s approaching a heat-danger zone for dairy cattle. Due to cows’ much-larger bodies and the immense work they must do to process food through four stomachs and produce gallons of milk daily, they’re more prone to overheating and increasingly vulnerable to climate change.
And because dairy cows are pregnant each year to produce milk, heat stress can negatively affect the cow as well as her fetal calf in utero. And it can affect that fetus’ future babies, through diminished reproductive systems in both mom and baby.
A damaged reproductive system in dairy cattle is, simply put, less productive.Cows suffering from overheating can produce as much as 30% less milk. That makes profits smaller for dairy farmers already working on tight margins, and puts pressure on the cost of dairy products.
It can mean as much as $3 billion lost dairy productivity annually, Laporta Sanchis said.
“These drops can really (mean) less milk, less cheese, less yogurt, a tighter supply (and) higher retail prices,” Laporta Sanchis said. “And the producers have to maintain a steady production throughout the year.”
Her lab investigates strategies farmers could deploy, and when, to keep their dairy cattle herds healthy. Giving cows ample protection from the unforgiving sun in barns is a costly capital expense, but vital to their health. Feeding dairy cattle at cooler times of the day might help them eat more. Just like humans, cows don’t feel particularly inclined to chow down a heavy meal as temperatures warm. Misting or showering the cows can also work, but its success is largely based on the climate around them.
Laporta Sanchis grew up in Uruguay, an eastern-South American country with about 3.3 million people where there’s four cows for every person. But she never expected to work in dairy research. She grew up around agriculture — her grandfather was a rancher who raised beef cattle and sheep. She studied sheep as an undergraduate and focused on beef cattle while pursuing her master’s degree.
It wasn’t until she arrived in the Wisconsin Dairyland to start work on her doctorate that Laporta Sanchis turned her focus to milk-producing cows. After finishing her degree she joined the dairy faculty at a college in Florida, where heat stress on cows is prevalent. She and her husband in 2020 came back to Wisconsin; he’s now a professor in the UW-Animal and Dairy Sciences Department.
To test for heat stress and its effects on dairy cattle, Laporta Sanchis and researchers in her lab take blood and tissue samples. They conduct biopsies on cows who call the University of Wisconsin home, at Madison as well as at the UW-Arlington Agricultural Research Station and the UW-Marshfield Agricultural Research Station. Researcher focus is primarily on calves and heifers. They examine how heat stress and nutrition affect mammary-gland-tissue growth.
If heat stress to the heifer prevents those mammary glands from growing as large as they should be, the natural result will be reduced milk production. Future generations of dairy cows will be born smaller and weaker, and will become sick more often if their mothers and grandmothers suffered heat stress, Laporta Sanchis said.
“Climate change, unfortunately, despite our individual and collective efforts, it’s here to stay,” she said. “So our job is to fight climate change as much as we can. But the cows need a solution today, and so that’s where we come in with developing nutritional strategies (and) management strategies. (We) try to help them do what they do best, which is make milk.”
Cows have very different sweat glands than we do, Laporta Sanchis said. “We’re able to sweat more efficiently,” she said. “If you have ever seen a horse run, they sweat a lot because they have different types of sweat glands, more like the ones we do. Cows have different (glands) and so they are less efficient in getting rid of heat.
“They generate a lot of heat because they have this big rumen. They have four stomachs, and one of them is like a big oven. It’s full of microorganisms that actually are the ones that are converting the feed they eat, the grass and what we give them, into milk. So they are pretty amazing animals.”
“When you look at what’s in milk, there’s a lot of things, bioactive factors,” she said. “There’s proteins, there’s fat (and) there’s lactose. Some of those precursors in the milk are going to be made in the mammary gland, but a lot of those she has to pull from her body. Certain fats, calcium, energy — she has to do that.
“That’s why it’s very demanding. If you compare it to a breastfeeding mom, they have to eat healthy, because the milk is getting all of the nutrients that she needs to put in there.”
“Our summers are shorter, so we have 60 days of summer,” Laporta Sanchis said. “But we do have a lot of cows; we have a big impact on the industry. We make a lot of cheese and heat-stressed cows make less milk. And their (future) generations can make less milk.
“This is very relevant to Wisconsin. Summers are getting warmer due to climate change. There’s a lot of variability, and summers can be very warm, and they are getting warmer every year. I think predictions are saying like 2 to 3 degrees Fahrenheit since 1950, so that’s a lot, physiologically, to handle for cows. It can take a toll, not only in the cow physiology, but also in crops and and water scarcity and things like that come along with climate change. It’s a big problem.”
“There are many things (producers) can do,” she said. “Clearly, it requires capital investment. When you’re thinking about building barns and putting cooling systems that they have to deal with the water and electricity, I think that research has shown that they pay off. But it’s an investment.
“The other thing is nutritional interventions. Cows are going to decrease the intake of feed when they are hot, just like us. When it’s super hot, you don’t feel like eating; you just want to drink more. Cows are the same. They increase water consumption by 50% trying to cool themselves. We try to provide the perfect diet so that we can accommodate that drop in intake, because they need that feed to make milk.
“There’s a lot of research in that area trying to overcome the deficiencies that come with the stress. When cows sweat, they put out a lot of minerals in their sweat, like potassium. (We’re) trying to bring that back.
“Reproduction is very much impacted under heat stress. Cows can lose their pregnancies if it’s early enough. That’s a big impact on the farm … cooling strategies, nutrition and making a lot of water available to them so they can drink more and try to cool themselves.”
Source: Agri-View / Kimberly Wethal
