Story by: Kaine Korzekwa | Two assistant professors in the Department of Dairy Science have secured a total of $1 million in grants from the USDA’s National Institute of Food and Agriculture. Their research focuses on using cutting edge laboratory techniques to find molecular solutions to ailments that negatively impact dairy cattle productivity and efficiency.
Laura Hernandez is investigating ways to alleviate dangerously low levels of calcium in dairy cattle around the time they give birth. Also addressing the period around calving, Heather White explores the role of hepatic metabolism in the development of a fatty liver.
“Just like in humans, fatty liver has very negative effects in dairy cows,” White says. “What we have found is evidence of a gene that may predispose a cow to developing a fatty liver. Our goal with this grant is to investigate this gene and also how to best help cows recover.”
Approximately 60% of cows develop ketosis, which is commonly associated with a fatty liver, when they give birth and start making milk. Accumulation of fat in the liver decreases the efficiency of the liver to make glucose, which negatively impacts milk production.
White says that around the time of calving, cows may not be meeting the needs of lactation with their diet, so they begin to mobilize fat for energy. The issue arises when the liver can’t break down the incoming fat fast enough and begins to store excess fat in the liver.
Genetics enters the equation because the protein White is interested in may play a role in helping the liver break down fat. A change in the corresponding gene could lead to lower levels of fat breakdown and therefore fatty liver. As the individual liver cells begin to fill with fat, they are unable to carry out their important functions and decreased performance is the outward result.
“This $500,000 grant may help us discover many new ideas,” White says. “We are going to explore the causative role of this gene and its related proteins on fatty liver onset, experiments will allow us to find possible preventative measures that farmers can use when managing their cattle, and genetic testing may help us learn how to identify dairy cows with a predisposition for fatty liver so they can be managed accordingly.”
Hernandez’s work also focuses on alleviating dips in cow health around the calving period but she studies calcium, a mineral essential for cows, humans, and all other mammals.
“Calcium is pretty vital to almost everything in the body,” Hernandez explains. “Muscle contraction throughout the body relies strictly on calcium to occur, and individual cells rely on calcium as a signaling molecule. Calcium is also critical for bone growth and development in growing animals, and is the major component of milk as a result of this.”
Calcium is the largest mineral component of milk so after a cow gives birth she must begin to use the calcium in her body to make milk. Luckily for mammals like cows, they are able to pull calcium from stored bone reserves to put into their milk so there is enough left in their body for cellular activity and muscle contraction. However, the volume of milk that dairy cows must produce is so high that cows are unable to adapt their metabolism as quickly as other species and they can have a hard time getting their calcium levels back up right after having a calf. This can cause multiple other issues for the cows, says Hernandez. Among other conditions, they may tremble because their muscles can’t contract properly or get a uterine infection that makes it harder for them to get pregnant again due to the reduction in immune function that occurs during instances of low calcium availability.
To combat this, Hernandez has traced the pathway of how serotonin mediates the cow’s ability to begin drawing upon the bone calcium stores earlier to prevent the sudden and large drop of calcium seen at calving. If she can get a cow to tap into that calcium pool sooner, problems can be avoided. She wants to see if giving the cows one of the first molecules in the process, maybe through a natural feed additive, will help their calcium levels.
“There are some different solutions like diet changes currently used but none of them are as effective as they could be,” she says. “It is also a very hard problem to identify because there aren’t many outward signs that producers can see on the farm until it is too late and the cow is extremely ill.”
She adds that while 2-5% of cows will reach the severe clinical stage, the troubling number is that 40-50% will be categorized as subclinical, meaning they still lose productivity without progressing to outward symptoms. Across the country, that means almost $1 billion lost dollars per year. The state of Wisconsin loses approximately $125 million per year, and a further calculation shows a 112-cow dairy farm suffers roughly $12,000 per year to hypocalcemia alone.
Department of Dairy Science chair Kent Weigel says only 10% of these grants receive funding, and that grants related to improving nutritional performance, growth, and lactation of animals are among the most competitive.
“Dr. Hernandez and Dr. White are exceptionally talented young scientists with unlimited potential, and we are extremely lucky to have them at UW-Madison,” he says. “Furthermore, although both projects feature cutting-edge science, they also have practical implications for dairy farmers in Wisconsin and around the world. Doing great science is nice, but doing great science that has an impact is what really matters at the end of the day.”