GENOMIC HEIFERS: Understanding who is on top

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Adding genomics to genetic evaluations brings more attention to young heifers. There is increased accuracy to heifer indexes and new population benchmarks.  Even more significant are the Direct Genetic Values (DGVs) that are generated from the DNA results.  As you will see, the the very top heifers increase their genetic indexes significantly, while their full sisters, without high DGVs are not on the list. The DGV value makes the difference.

The Bullvine continually receives the question, “Why are the top heifers at the top?” In order to assist the industry to better know how high is great, the Bullvine has done an analysis of the top 25 Canadian Holstein heifers published in April 2012 by Canadian Dairy Network.

What do the average for the Top 25 look like?

This is a truly exceptional group. What other Top 25 female list would be able to boast of an average value of 192 kg. for fat plus protein and 13 for conformation on their Parent Average Genetic Indexes? And look at their DGVs. They are even higher at 203 kgs. for fat plus protein and 13.8 for conformation.

Digging Deeper

Average numbers are a good place to start, but there are additional facts that can assist us in understanding the Top 25.

• 21 were less than 1 year of age and 4 were over 12 months of age. Obviously, the heifers on this list are young.
• The prominent cow families represented on this list are: Lila Z (24%); Lead Mae (24%); Gypsy Grand (16%) and Laurie Sheik (8%).
• The heifers’ sires are 48% daughter proven bulls and 52% genomic young sires.
• The heifers’ dams are 40% with performance of their own and 60% with PA GLPIs only.
• 96% of the heifers have DGVs higher than their PA GLPI.
• The most significant fact is that the top 25 heifers on average have DGVs 228 LPI points higher than their PA GLPI. They are what are commonly referred to as high outliers. Most of these heifers have full sisters who are not as high for DGV. Previously, they would have been considered equals.

In future articles, The Bullvine will be bringing forward ideas on the genetic needs of dairy cattle and strategies to use in selecting and breeding.

THE BULLVINE BOTTOM LINE

When deciding to invest in a high genomics heifer, it is important to study both the heifer’s PA GLPI and her DGV. Although 25 may be too small a group to depend on for everything. Nevertheless from this small snapshot we get a clearer picture of the potential that genomics and DGVs provide.  The Bullvine is excited to provide this perspective on an ongoing basis.

Not sure what all this hype about genomics is all about?

Want to learn what it is and what it means to your breeding program?

Download this free guide.