University of Guelph researchers recently investigated the effects of acidified milk replacer on early calf growth. The study calves were randomly assigned to either free-access feeding of acidified milk replacer (via the addition of formic acid) or conventional milk replacer. Calves were fed milk replacer containing 24 percent crude protein and 18 percent fat. The target pH for acidified milk replacer was between 4 and 4.5.

Calves that received the acidified milk replacer had significantly higher pre-weaning body weight gain compared to the conventional calves, as well as greater change in hip width, hip height, body length and heart girth. The calves did not differ for post-weaning weight gain.

While formic acid can be used for this purpose in Canada, it can't be used for this purpose in the U.S., according to Food and Drug Adminisration regulations.

"There are a number of other acids (examples are citric and propionic) that can be used in the U.S.," says Larry Chase, dairy scientist at Cornell University. "There are also some chemicals used in preserving foods that may also work. There was a lot of interest in this in the 1970s, but little attention or interest until just recently," he adds.

Results from the Guelph study were presented at the American Dairy Science Association’s annual meeting, and indicate that free-access feeding of acidified milk replacer supports improved body weight gain and structural growth during the pre-weaning period, but does not affect post-weaning weight gain.