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Study: More milk gets calves growing faster, but no differences as cows

A newly published study supports findings from previous research. Calves grew faster before weaning on higher rates of milk or milk replacer, but size differences disappeared after weaning and milk production in first lactation was not affected.

The latest research on the topic of calf growth rates and first lactation milk production was recently published. A large study from the University of Guelph in Ontario (Kiezebrink et al., 2015) appeared in the January issue of the Journal of Dairy Science. Calves (152) were fed either 4 or 8 liters of whole milk (in 2 feedings) each day and housed individually in an indoor facility. Calves fed more milk grew faster for the first 4 weeks of life, but average daily gains were not different in weeks 5 through 8 (before weaning), and calves fed the higher rate of milk ate less calf starter and drank less water. From weaning on, all heifers were fed the same diets. After weaning, calves fed the higher rate of milk maintained an advantage in body weight and withers height, but calves on the lower milk feeding rates with greater ad lib grain intakes grew faster. When measured at 4 months of age, differences in withers height disappeared, and at 12 months of age heifers in the two groups had similar body weights. All heifers were treated the same and were followed through their first lactation. Age at calving (24.6 months), post-calving body weight (1306 lbs), total milk, milk fat, and milk protein production were equal for both groups; milk production for 305 d was 19,195 lbs for the low milk fed group and 19,140 lbs for the high milk fed group. The researchers concluded that there was no advantage to feeding higher levels of milk on overall growth and production.

This now makes 5 separate studies where identical feeds were fed in standard or high levels and all 5 studies have shown similar results. Calves grow faster before weaning on higher rates of milk or milk replacer, but in all studies, this size difference disappeared after weaning. Only one study, from the University of Minnesota, found that some of the added costs of the extra liquid feed were recaptured by heifers calving earlier. All of the studies have shown no effect on first lactation milk production. With some further genetic analysis it was mentioned by the authors of the study at Michigan State that they saw a trend for more milk for faster grown heifers; however, their primary conclusion was no differences. It is of note that there are no studies done anywhere in the world (published) using a comparison of the same feeds fed at different levels that found an improvement in milk production. One study that is often quoted as showing this effect was done by Cornell University. All of the calves in that study were fed the same high level of milk replacer, there was no control for comparison. Therefore no conclusions can be made in relation to level of milk feeding from that study. Also in that study the researchers had limited health information and little calf starter intake information to help account for any differences. What that study did show is that calves that are gaining more weight at weaning—likely because of being healthier, eating more calf starter, and possibly being genetically superior—are animals that give more milk in the first lactation. They also showed that there are seasonal impacts on growth rate of calves and on lactation performance of first-calf heifers. All of these effects have been shown in multiple other studies and are logical. The only published studies that did show differences in milk production for calves fed on a high versus low plane of nutrition are three Israeli studies comparing ad libitum whole milk feeding versus an inferior quality (by our US standards) milk replacer. Since US milk replacers provide higher levels of nutrition, the results of these comparisons do not apply under US feeding conditions.

To conclude, calf feeding programs providing 4 to 5 quarts per day of milk or milk replacer and encouraging calves to eat large amounts of high quality calf starter to develop and utilize the rumen are more economical than feeding large amounts of milk or milk replacer. The cost of protein and energy per unit is far more expensive when it comes from milk or milk replacer than grain; yet the value to the calf is similar or higher when from grain. Rumen development is stimulated by grain intake and not milk intake, and a well-developed rumen can produce high quality protein and energy for the growing heifer. If your goal is to market weaned calves (as is the case with veal producers), then feeding high amounts of liquid feeds makes sense. However, if your goal is to milk first lactation heifers, then a more traditional level of liquid feeding is appropriate.

Source: Penn State Extension

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