New research presented by at the American Dairy Science Association annual meeting this past July in Denver looked at the effects of free-access feeding acidified milk replacer on pre and post-weaning growth of Holstein replacement heifers and veal calves.

The study was conducted by researchers at the University of Guelph at a commercial dairy operation in central Ontario, Canada. Heifer calves were reared as replacement animals and male calves were marketed as grain-fed veal. Calves were randomly assigned at birth to one of two milk feeding programs: free-access feeding of acidified milk replacer or conventional (3 liters fed twice daily) feeding of milk replacer. Calves were fed milk replacer containing 24 percent crude protein and 18 percent fat. Formic acid was used to acidify the milk replacer for the acid treatment. The target pH for acidified milk replacer was between 4.0 and 4.5.

Calves were gradually weaned from milk replacer at approximately six weeks of age. Body weight, hip width, hip height, body length and heart girth were measured at birth and weaning. A post-weaning body weight measurement was also collected for each calf. There was no difference between the acid and conventional calves for any of the measurements collected at birth. The acid calves had significantly higher pre-weaning body weight gain compared with the conventional calves, as well as greater change in hip width, hip height, body length and heart girth. The acid and conventional calves did not differ for post-weaning weight gain.

These results 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.