If a cow has never been on pasture, it may take her a few days to learn how to graze, a University of Wisconsin-Madison study suggests.

Dairy scientist Dave Combs compared behavior and performance of barn-dwelling cows turned out on pasture for the first time in their lives to that of cows raised on pasture. In addition to measuring milk production, he used GPS devices to track their movement around the paddock.

“We found that there clearly is a learning curve,” Combs says. “Cows that had never seen a blade of grass had differences in performance relative to those heifers that had been exposed to grass as growing animals.”

Milk production dropped as much as 10 lbs per day for lactating cows newly introduced to a pasture, mostly because they didn’t eat as much when they first arrived, he reports. But they adapted quickly. By the end of the first week on pasture, milk production was essentially the same.

Cows that were new to pasture didn’t seem to understand why there were there, Combs says. When they first arrived, they tended to stand by the gate looking for a way back to the barn. Meanwhile, the pasture-savvy animals fanned out and walked as much as four miles a day. But within a few days, it all evened out.

“Over the course of a week, all the animals, whether they were experienced or not, walked about two miles a day,” he says. “The experienced ones kind of scoped the pasture out the first couple days and then became more efficient. The heifers that had not seen grass at some point figured out that they had to begin to eat and began to actually graze.”

Combs did the study to learn more about designing research geared toward the needs of pasture-based dairy operators. The university has stepped up its grazing-based dairy research in recent years, using cows from its regular research herd, which are raised and housed in barns. But some grass-based farmers wonder if the findings apply to their operations, and have urged the university to create a separate, grazing-based herd.

Combs says the study suggests that grazing research done with cows pulled from the main university herd should yield information that applies to pasture-raised cows – as long as the learning curve is taken into account.

“From a farmer’s perspective, this is probably the kind of commonsense thing,” he says. “If you put an animal in a new environment, probably you (should) provide some feed that they're familiar with so that they can make that transition. An abrupt switch causes stress and it takes a couple days for these animals to adapt to that environment.”