Transition cows go through many physical changes in the three weeks before calving and the three weeks after. At that same time, milk production is often soaring, and some cows can already be producing 100 pounds of milk or more by the end of the first week of lactation, noted veterinarian Jessica McArt.

“Lactation initiates massive changes in nutrient and micromineral demands,” said McArt during the October Hoard’s Dairyman webinar. As a result, many cows enter a period of energy deficit, or negative energy balance, in early lactation.

“Increases in dry matter intake lag behind the requirements for milk production,” explained McArt, an associate professor at Cornell University. There is a six-to-eight week period when cows are expending more energy than they can take in.

To produce 100 pounds of milk, a cow needs to eat 53 megacalories of metabolizable energy, she said. In comparison, a human running a marathon at a 9-mile per minute pace would expend 3.2 megacalories. When adjusted for body weight, McArt shared that high-producing cows are running 1.6 marathons a day, metabolically speaking. Even more impressive is their stamina. “They are doing this today, tomorrow, and the next day,” McArt stated.

Cows have physiological ways to deal with this elevated energy demand in early lactation, she noted, and many handle it well. The cows that don’t, though, won’t milk as well, have reproductive challenges, and are at greater risk for disease.

Caretakers can help cows through this transition by providing the proper environment, nutrition, and other strategies that support early lactation needs. “Our goal is to help cows have a smooth transition into lactation,” said McArt. “We want to focus on comfort and nutrition during this whole transition period.”

To learn more, watch the Hoard’s Dairyman webinar, “Start ‘em right with tools to ensure fresh cow success.” This webinar was sponsored by Boehringer Ingelheim.