5. Heifers and lame cows will suffer first. Natural animal behavior dictates that dominant animals will gain more ready access to stalls. In Hill’s research, he found that milk production started to drop in first-calf heifers mixed with older cows when they were just 15 percent overstocked. He found that lame cows started to lose production at the same threshold of 15 percent overstocking when mixed with healthy cows.
So what is the ideal stocking density? “Unfortunately, there is no ‘magic number,’” says Krawczel. “It really comes down to adjusting up and down from your current level.” Barn design, stall design, 2X or 3X milking, location of waterers, weather, bedding and a host of other factors have bearing on the decision, he says, noting that 120 percent is a reasonable number to work around in many cases.
At the Birker Dairy in Iowa, they have arrived at a stocking density of 120 percent for first-calf heifers and 112 percent for higher-parity cows. Ken Birker adds that those numbers always are fluid, and are regularly re-evaluated based on current weather, feed and cow health conditions.”
Hill says his experience has shown that stocking density is intricately linked to virtually every aspect of cow health and performance – milk production; udder health and milk quality; fresh-cow health; foot and leg health; estrus expression and reproductive efficiency, and more. Less-than-optimal results in any of those areas could be linked to overstocking.
For example, “a lot of people try switching to 3X milking and are disappointed that they don’t see much of a response,” shares Hill. “The reason could be that the herd’s stocking density is too high, and then they are asking even more of their cows. The cows get even less rest, and they just can’t respond with higher production. I firmly believe the most successful dairies are the ones that make their decisions based on what is best for the cow,” he says. “If the cows are comfortable and healthy, everybody wins.”