U.S. dairy genetic evaluations undergo a base change every five years, keeping "average" around "zero." The December 2014 genetic evaluations were based on animals born in 2010 that now have enough information to evaluate their full genetic potential for the first time.
Today, a cow with a "zero" breeding value for any trait is average for that trait when compared to the U.S. cow population. Five years from now, with subsequent genetic improvement, that current "average" animal becomes less comparable to the total cow population.
After you are over your initial reactions to the changed December genetic values, take time to think about the genetic progress made in the U.S. over the past five years. The average Holstein improved genetically by 382 lbs. of milk, 12 lbs. of protein, and 0.99 on Type.
For health traits, the Holstein cow improved on Productive Life (PL) and Daughter Pregnancy Rate (DPR), but did not improve on direct or maternal calving ease or stillbirth. The result of the industry"s collective genetic selection has slowed the rate of genetic progress for production from 10 years ago, but this change has allowed a positive genetic response in reproductive health traits.
This can be a good tradeoff if the genetic pendulum has swung too far in favor of one trait or another. You should consider these changing population dynamics when you determine your herd breeding goals. Does your herd follow the general trends, or do you need more emphasis on certain traits then the rest of the population?
Next, you should carefully select traits needing the greatest improvement in your herd, buying sires that will help in those weak areas. Stick to a plan, avoiding the hot-bull-of- the-month sales pitches.
Highest not always best
Another challenge to genetic progress is how dairy farmers utilize genetic evaluation numbers. Looking at a list of genetic evaluations, it"s easy to guess that the highest is always the best. No matter what trait or the trait heritability, higher is always better is a standard belief.
But this is just not true. Selecting for the very highest PL or DPR, or lowest somatic cell score (SCS), may not be the best method to achieve overall profitability. These low-heritability traits change very slowly over generations, and extreme emphasis on them could limit your progress in more highly heritable profit traits, like milk or protein.
More overall economic progress could be made by never selecting a sire below-average for health traits. Then, from the remaining sires, select those with more potential to quickly impact your bottom line.
Many dairy farmers now sort sires by looking for extreme health traits, readily accepting the resulting sires from their selection process are negative, or just barely positive, for many highly heritable economic traits. The computer-assisted selection of minimums for a trait (truncation selection) has misled more breeders into poorer sire choices than they realize. Sires are being utilized that are minus for milk or very low for component percentages, because they are extreme for DPR, SCS or PL.
Health traits are important, but if you achieve way less production as a result, have you improved your bottom line?
The solution: never select a sire that is minus or low for a health trait. Doing this ensures you are making genetic progress, and then maximizing the highly heritable traits leading directly to making more profit. This method also avoids the pitfalls of truncation selection.
If you really want to achieve maximum genetic progress for health, cull females phenotypically and genetically weak for health traits rather than continue to propagate their genes. You will improve your herd genetic values for health quicker than using sire selection alone.
Follow your plan
Develop a plan for economic profit based on improving your herd"s genetic weaknesses. Take into account the heritability of traits you are emphasizing when prioritizing your important needs. In your sire selection, remember to include an analysis of potential inbreeding problems. Finally, buy a portfolio of sires that achieve your plan of adding desirable genes to your herd. Do not deviate from your goals.
For more information on December 2014 sire evaluations, visit the Council on Dairy Cattle Breeding website at www.cdcb.us/eval.htm.