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Primed and ready to go: A closer look at epigenetics

Beth Keene and Melanie Soberon for Progressive Dairyman Published on 18 July 2018

What do heat stress, low-quality colostrum and lower-than-average daily gains during the pre-weaning period all have in common? Each of these can impact the expression of a dairy heifer’s genetic potential, translating into lifetime effects such as lower milk production, lower reproductive efficiency and decreased longevity.

Similarly, decreased heat stress, high-quality colostrum and reaching target pre-weaning average daily gains can have the opposite effects, yielding higher milk production potential, improved reproductive efficiency and increased longevity.

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A new and exciting science known as epigenetics is shedding light on the importance of early developmental stages as they relate to future productivity in multiple species, including humans and dairy cattle.

More specifically, epigenetics is helping us understand the importance of certain physiological changes that take place in dairy calves due to their environment and nutrition in the first months of life.

The results of recent epigenetic studies are better informing current calf feeding strategies, especially in the first 60 days of life. For example, a 2012 study at Cornell University demonstrated the profound impact growth rates in this pre-weaning time period can have upon a cow’s performance later in life.

In this study, for every additional pound of average daily gain pre-weaning, heifers would produce over 800 pounds of additional milk in their first lactation.

This was further confirmed when Fernando Soberon, technical services manager at Trouw Nutrition USA, and Mike Van Amburgh, professor at Cornell University, analyzed over 14 scientific studies in a meta-analysis that revealed an even stronger correlation between pre-weaning growth rate and subsequent milk yield.

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Furthermore, we have learned positive effects can be “lost” due to poor nutrition pre-puberty. Most importantly, the opportunity to modulate the epigenome is only available during specific time periods of development and, if those windows of opportunity are not utilized, these efficiencies cannot be regained later.

The first stage where epigenetic programming can be directly affected is during development in utero. This translates into the dry period for most practical reasons.

A study from the University of Florida has shown heat stress during the last trimester of a cow’s gestation has profound effects on growth rates, milk production and survivability of the pre-born calf. Thus, minimizing heat stress and fulfilling nutritional needs of dry cows is important to set the pre-born calf up for success.

The next and likely most influential area of opportunity occurs during the first few hours of the calf’s life via the colostrum it receives. At this point in time, both the amount given and the quality of the colostrum are critical factors in priming the calf for future life productivity.

The quality of the colostrum is determined by the dry cow program as well as the timing of collection post-calving.

As for the amount of colostrum, a research study in Brown Swiss calves conducted in 2005 observed improved growth rates, a 12 percent increase in survival throughout second lactation and 2,200 pounds more milk produced over two lactations in calves fed 4 quarts of colostrum in the first two hours of life versus those calves that received the traditional 2 quarts.

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Therefore, it is recommended producers provide 3 to 4 quarts of high-quality colostrum within the first two hours of birth and an additional 2 quarts in the subsequent feeding.

There remains yet another area of opportunity for producers who wish to prime their calves for their maximum potential in the pre-weaning period, and that is pre-weaning growth rate.

Doubling the calf’s birthweight and achieving 4 to 5 inches of structural growth by 56 days are attainable growth rate goals in the pre-weaned period that will aid in the programming of a successful future dairy cow. For the average Holstein farm, this would translate to weaned calves over 200 pounds.

There are a number of management considerations that are critical toward achieving these target average daily gains. They include proper environment (ventilation and bedding), proper sanitation (feeding and cleaning equipment) and proper nutrition (2 to 2.5 pounds of dry matter per day in the milk-fed phase).

The pay-off comes later in life if this growth is supported throughout puberty. Not only are higher milk yields witnessed in heifers with these target average daily gains but, as cows, these animals have improved conception rates, higher bodyweights at calving and overall increased longevity.  end mark

Melanie Soberon is a freelance writer based out of New York. She has a Ph.D. in ruminant nutrition and teaches at Cornell University during the summer.

Beth Keene is a calf specialist with Trouw Nutrition USA. Email Beth Keene.

Take-away messages

  • Epigenetics is a powerful concept. There is a narrow window of opportunity to make lasting impacts on lifetime performance.

  • Feed colostrum for the first two to three days of life.

  • Aim to feed 2 to 2.5 pounds of dry matter solids during the pre-weaned period to maximize bodyweight and lean muscle growth.

  • Take weight and height measurements at birth and weaning to manage and monitor progress.

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