The Crossroads Between Nutrition and Genetics

February 21, 2019 10:05 AM
 
Your rations bring your cow's genes to life.

If you build a race car and put a high-performance engine under the hood, it won’t do any good to pour in regular old gasoline. It takes specially formulated, high-octane fuel to help that engine perform at its peak, race after race.

The same can be said for your dairy cows. It’s like if you were to spend years pouring over genetic profiles and genomic tests to come up with the best matings to advance the genetics of your herd, then spend five minutes building a simple ration. You wouldn’t be giving your cows the chance to fully express their high-powered genetics.

YOU ARE WHAT YOU EAT

“What an animal eats can impact how genes are expressed,” says Amanda Gehman, research project manager with Alltech. “So the genes and genetic code dictates the potential for an animal, then the feed the animal gets and how it interacts with nutrients determines how much that animal can express its genetic potential.” It’s nature and nurture.

“You can’t separate nature and nurture anymore. It’s not one or the other,” Gehman says. “Nature is the cow’s genetic code inherited from its parents, including heritable traits influenced by feed consumed by the parents, while nurture covers what that animal eats and its interaction with how their genetic code is expressed.”

2% MAKES THE DIFFERENCE

When considering a nutrition program that maximizes genetic expression, Gehman says to remember there isn’t much variation, genetically, between cows. “About 98% of the genome between cows is the same,” she says. “However, that 2% is super important because those genes are encoding for the proteins that have anything to do with hormone reception, carbohydrate metabolism, protein metabolism, reproduction and so forth.”

It’s that 2% that makes some cows produce and reproduce better than others. The foundation of breeding programs is dedicated to making that 2% the best it can be.

Yet there is a different environment inside the cow that is even more variable, Gehman says. That’s the environment inside the rumen, where microbes create a different and diverse population.

“When we talk about ruminants, there is also the rumen microbiome, and that’s a completely different animal,” Gehman says. “That environment is definitely different among cows and among species, and between cows that are on one farm versus another.”

These microbes within the rumen, Gehman says, are very responsive and adaptable to nutrition.

It’s important to understand how these environments, the rumen microbes and the cow, interact when thinking about building a ration that will accentuate the genetic capabilities of each population.

THE NUTRIENT PATHWAY

“It’s hard to separate the rumen from the cow, because the impact of the diet on the rumen microbiome impacts what the rumen microbiome produces,” Gehman says. “And that impacts what the cow receives from those microbes. So the diet that comes out of the rumen is much different from the one that goes into the cow’s mouth.”

Research in the industry is looking at the impact nutrition has on gene expression throughout that pathway from rumen microbes to cow performance. For example, Gehman says they are looking at how a change to the expression of a protein that’s encoded for protein metabolism impacts amino acids and other products of digestion. The examination continues further down the pathway to how that system affects milk composition and production.

The process is complex, Gehman says. “Nutrigenomics is being used as a research tool,” she says. “We’re working toward making recommendations based on these findings.”

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