When Ken Birker sold off 15 percent of his herd a few years ago, he naturally expected the milk in his bulk tank to go down, at least temporarily. Funny thing is, it never happened.
“We were milking about 400 cows at the time, and made a strategic decision to focus on our better animals and switch to three-times-a-day milking,” the Vinton, Iowa, dairyman explains. “It was our hope that we could eventually return to the same level of production with fewer cows, but certainly did not expect that it would happen so quickly– essentially overnight.”
In retrospect, Birker believes the remaining cows responded to an improvement in stocking density – easier access to feed and water; higher per-cow feed intake; and improved free stall accessibility, which allowed for more hours of rest per day, improved rumination and healthier feet and legs.
His experience is no surprise to Chris Hill, nutritionist for Poulin Grain, Inc., who consults with dairies throughout Vermont’s Champlain Valley. Prior to his current job, Hill managed three dairies and worked on a number of others – some large, some small, and with varying priorities regarding animal behavior and cow comfort. “After working on several dairies, I was impressed by the improvements in herd healh, reproduction and milk production I saw on the farms with excellent cow comfort and stall availability,” he says.
Lessons in cow comfort
Motivated by these observations, Hill returned to graduate school at the University of Vermont and chose to place his research emphasis on stocking density and animal behavior. His trial work was conducted at the nearby Miner Institute at Chazy, N.Y., where he collaborated with Peter Krawczel, PhD, who is now in the Department of Animal Science at the University of Tennessee.
Both researchers attempted to identify the ideal stocking density that would allow cows to behave naturally, for the best possible health and productivity outcomes. Among the results they found were:
1. Cows will choose rest over eating. Cows need between 10 and 14 hours of resting time per day, and three to five hours for eating. The remainder of the time is allocated to travelling to and from the parlor; milking; drinking water; grooming; social behavior and estrous activity. But they prefer rest over all other behaviors, and if adequate resting space is not available, they will sacrifice time for other activities to rest when they can. Krawczel cites a study that also showed an increase in the level of the stress hormone cortisol, and a decrease in growth hormone, in cows that were deprived of adequate resting time. And, in their work at the Miner Institute, they found an advantage of 3.7 pounds of milk per day for each extra hour of resting time that cows received. “It is a fallacy that if cows aren’t lying down it is a good thing, because that must mean they are up and eating,” says Hill. “I’ve spent a lot of time observing cows at all hours of the day and night, and too often we see cows just standing around doing nothing. They are interested in resting, not eating, but they cannot find the space to lie down. They simply run out of hours in the day to get it all done.”