It is not uncommon to evaluate milk replacers on a cost/bag basis in an effort to control cost. The standby has been the 20% protein:20% fat milk replacer fed at a rate of 1.0 lb. of powder fed in 4 quarts of total liquid per day. Attempts to improve growth have lead many companies to offer replacers containing 22%, 24% and up to 28% protein. Naturally these higher protein milk replacers are more expensive. Research has shown that greater lean tissue growth occurs with the higher protein milk replacers. Similarly, there are varying levels of fat in milk replacers from 10% to as much as 25%. The lower levels of fat are probably adequate for summer time feeding, while the 20% fat levels are more appropriate for winter when energy requirements are higher. Replacers with 25% fat are recommended for smaller breeds such as Jerseys with higher maintenance requirements.
However the most important concept to remember in feeding calves is that the percentages are not as important as the total amount of protein or fat consumed. Following is a comparison of the amount of protein consumed with a 20 or 28 %CP milk replacer containing 20% fat fed at two different rates.
|Amount of Milk Replacer|
|20||0.20 lb. CP||0.40 lb. CP|
|28||0.28 lb. CP||0.56 lb. CP|
Feeding the higher protein milk replacer at a low feeding rate only changes the amount of protein consumed by 0.08 lb. per day and provides enough energy to increase gain by 0.06 lb. and enough protein to increase gain by 0.3 lb. One can expect much better gains from the higher feeding rate. At 68oF increasing both nutrient content and amount per day fed to a calf supports better tissue gain and overall growth rate. Feeding a low level of milk replacer is usually insufficient to support any growth at all, especially during all seasons but the summer.
Responses to fat level are interpreted differently. Lower fat levels may be adequate during the summer when energy needs are lower. However, as temperatures drop below 50oF, increased energy is required and there will be responses to higher fat% milk replacers when fed at higher levels. This is especially critical for the calf during the first two weeks of life when calf starter intake is negligible. More efficient gain is achieved by feeding higher component milk replacers at higher levels of intake. Nutrient demands for growth demand higher levels of intake from milk replacers, especially during winter and in adverse housing conditions.
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.
December 21, 2012