Intensified feeding of calves has gained a lot of interest. In a research experiment at Michigan State University, Holstein heifer calves were randomly assigned to one of two dietary treatments, with an average of 40 head per treatment.
Treatments continued from 2 days of age until weaning at 42 days of age. The first treatment was a conventional diet that consisted of a standard milk replacer (21.5 percent crude protein and 21.5 percent fat), fed at 1.2 percent of body weight on a dry matter basis and starter grain (19.9 percent crude protein) to attain about 1 pound of daily gain. The intensive diet consisted of a high-protein milk replacer (30.6 percent crude protein, 16.1 percent fat), fed at 2.1 percent of body weight on a dry matter basis and starter grain (24.3 percent crude protein) to achieve 1.5 pounds of daily gain. All calves were completely weaned at 42 days of age and kept in hutches to monitor individual starter consumption in the early post-weaning period. Starting from 8 weeks of age, heifers on both treatments were fed and managed similarly for the duration of the study. Body weight and skeletal measurements were taken weekly until 8 weeks of age, and once every 4 weeks thereafter until calving. Calves consuming the intensive diet were heavier, taller, and wider at weaning. The difference in withers height and hip width was carried over into the early post-weaning period, but a body-weight difference was no longer evident by 12 weeks of age. Heifers fed the high-energy and protein diet were 15 days younger at conception and 14 days younger at calving than heifers fed the conventional diet. Preweaning costs were higher for heifers fed the intensive diet. However, total costs measured through first lactation were not different. Researchers conclude that intensified feeding of calves can be used to decrease age at first calving without negatively affecting milk yield or economics.
This research was published in the July 2011 Journal of Dairy Science.