Researchers are starting to understand more about why some cows are more predisposed to subacute ruminal acidosis than others.

In one study, researchers offered a grain challenge to cows fed a higher forage diet and cows fed a lower forage diet to induce subacute acidosis or SARA. “The cows on the higher forage diet, in general, experienced less acidosis than cows on the lower forage diet,” explains Karen Beauchemin, research scientist with Agriculture and Agri-Food Canada. That is what you would expect to happen.

However, even though the cows were all challenged in the same way, not all responded in the same way. “There is a lot of variability among cows,” Beauchemin acknowledges.

That’s because there are several factors involved in the development of SARA. “One factor that predisposes cows to acidosis is stage of lactation,” Beauchemin says. Cows in early lactation are extremely susceptible to acidosis. “It all comes down to how we manage them going from the dry period to early lactation,” she adds.

The effect of repeated bouts of acidosis on the cow also is an area of research currently under study. In one experiment, Beauchemin and colleagues repeatedly “challenged” cows — essentially, by feeding them grain on an empty stomach — to induce acidosis. “The effect of the acidosis challenge was more severe with each subsequent challenge,” Beauchemin says. Once a cow experiences a bout of acidosis, it takes less effort to induce another bout, she explains, and the subsequent episode is much more severe.

“How cows transition into the early stages of lactation is really important because if they do get acidosis, they are going to be much more susceptible to acidosis later on,” Beauchemin stresses.