Friday, October 30, 2015

Selection for Improved Feed Efficiency

DNA Technology: Where we've been, where we are, and where we're headed
Conference sponsored by the Beef Feed Efficiency grant, beefefficiency.org

Meat Animal Research Center, Clay Center, NE

Matt Spangler
University of Nebraska-Lincoln


In poultry, we have seen a 250% improvement in feed efficiency since 1957. We have dramatically improved the efficiency of gain in chickens.

We have not made similar progress in beef cattle. How can we move the needle and start to make progress?

First of all, how do we define feed efficiency?

  • Average daily gain (ADG)
  • Average daily feed intake (AFI)
  • Residual feed intake (RFI) is the difference between what we expected an animal to eat and what they actually ate. In residual feed intake, how we define a contemporary group is very important. For example, think of combining Scottish Highland and Chianina cattle in a group. 


EPDs for feed efficiency

  • Residual gain
  • residual feed intake
  • dray matter intake
  • Days to finish


If a breed publishes multiple efficiency EPDs, which one do I choose?
Hint: The answer comes below! Spoiler alert, economic indexes!

Getting feed intake records can be very expensive. It is probably not feasible for a large number of feed intake phenotypes to enter national cattle evaluation. Genomics helps us collect phenotypes on
a manageable number of animals and use that data to predict feed intake in a much larger population.

With genomic testing, we can account for a large portion of the genetic variation in feed intake and about 30 to 40% of the overall variation in feed intake (phenotypic variation).

The largest effect genes in feed intake

We want to select for the most profitable animals. We don't want the most productive cattle or the most efficient cattle, but the cattle that best combine production and efficiency to be profitable.

Depending on how we measure feed efficiency, cattle rank differently.

Do we want to estimate the relationship between two traits? Such as feedlot efficiency and cow efficiency.
Spangler says, "Collect, record, estimate". If producers want to know the answers to these types of questions, they need to turn the data into breed associations.

We need to think about efficiency in terms of economic returns. An economic index approach is the optimal way to make change in many different traits.

"These large USDA grants are a jumping off point for breed associations," Spangler said.
The breed associations and beef industry will then need to create methods to continue to collect the data.

For a video of this talk see the conference website: http://www.beefefficiency.org/annualmtgoct15.html


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