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MAES scientists study accelerated heifer growth program
Michigan State University scientists are studying the effects of an accelerated heifer growth program.
Studying the effects of an accelerated heifer growth program on age and body weight at puberty and future milk production is the focus of a long-term investigation conducted by Michigan State University's (MSU) Michigan Agricultural Experiment Station (MAES) animal science researchers Miriam Weber-Nielsen and Mike VandeHaar.
"Replacement heifers are the future of the milking herd," Weber-Nielsen said. "Optimal management of heifers from birth through calving is important to ensure their success as lactating cows."
Ideal body weight before calving is important regardless of age at calving. Increasing prebreeding growth rates of heifers allows them to calve at a younger age, decreasing the amount of unproductive time for young dairy calves, and potentially reduces the cost of raising the calves. For accelerated growth programs to be effective, however, the calves need to reach adequate weight and size at calving without compromising mammary development or productivity.
"Intensive feeding or accelerated growth programs have been developed to increase preweaning growth rates of calves with one goal -- attaining breeding weight at a younger age," Weber-Nielsen said. "Until recently, however, these programs had not been evaluated for their effect on the mammary development and future milk production potential of calves."
Earlier MSU research demonstrated that rapid growth rates in heifers for more than three months between four months of age and puberty led to reduced milk production. This negative effect of rapid growth rates on milk production is likely related to decreased growth capacity of mammary tissue in response to high energy intake.
"If the calves reach puberty early, mammary development may be compromised unless mammary development also occurs at a faster rate," Weber-Nielsen said. "We want to determine whether calves' growth rate can be accelerated without compromising milk production."
In the current study, MSU researchers are targeting the first six to eight weeks of life as a period in which increased heifer growth may be achieved without producing fat heifers. They will analyze the effects of using milk replacer containing 15 percent fat and 28 percent protein rather than the 20:20 percent milk replacer currently used on many dairy farms. The researchers predict that increasing the amount of protein without increasing the fat levels should produce lean growth at a faster rate.
The higher protein milk replacer is more concentrated than the traditional product and therefore needs to be fed with additional water. It is also more costly -- typically $50 to $80 more per 50-pound bag.
Several growth indicators from birth to first lactation are being observed and recorded through the course of the study. Milk production and health incidents during the first 150 days of lactation will also be recorded and included in the research findings.
In addition to studying the growth and production factors, the project is also looking at economics. MAES agricultural economist Chris Wolf will conduct a cost analysis for the accelerated growth program.
"We will look at all the factors before any recommendations are made for an accelerated growth program," Weber-Nielsen said. "Ideally, we may be able to find a program that allows the heifers to begin their first lactation a month or two earlier than average for a particular farm, which eliminates 30 to 60 days of non-productive time."
Source: MSU
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