By Robert C Goodling
Use of a selection index, such as Net Merit, can help producers capture the most genetic gain and economic value when making breeding decisions. The Net Merit formula will be adjusted, a new Grazing Merit index will be calculated, and a base change will occur with the release of the December 2014 proofs.
Increasing and sustaining profitability are crucial to the success of any business, including dairy operations. Most people consider that to do this, they need to cut their costs, be it feed costs or equipment costs, hope for higher milk prices, or increase production. Herd profitability is continually affected by the breeding decisions made on the dairy too. Every new generation of first lactation heifers that enter a herd should be genetically superior to the previous generation. Most producers see milk production as the key way to increase profitability through genetics, and to a point this is true. But there are other considerations that should be involved. Milk components have become more and more important in determining the value of a milk check, and let’s not forget the benefits of those somatic cell premiums. With so many traits playing a partial role in overall profitability, it can become quite complex when deciding what emphasis needs to be placed on which traits.
To alleviate some of these concerns, there are a variety of selection indices available to producers to help make genetic gains in more than one trait at a time, while emphasizing traits with the most economic importance. The merit indexes are designed to evaluate the economic potential of a bull’s daughter. Currently, three merit indexes are published quarterly: Net Merit, Fluid Merit, and Cheese Merit. An additional merit index, Grazing Merit, will be available in December 2014. Fluid, Cheese, and Grazing Merit indices will be addressed in detail in a subsequent article.
Probably the most popular of the merit indexes, Net Merit is designed for overall production. Fat and protein production have the most weight in the model, but it also considers productive life and milk production, as well as type and health traits. It is designed to be profitable for producers selling milk in any of the wide range of milk markets across the U.S. Net merit is designed to predict the expected lifetime profit over that of a breed-specific, base genetic population. In the 2014 version, the base cow for each breed was born in 2010.
In December 2014, revisions to Net Merit will be introduced. The minor changes resulted in a 0.965 correlation of the 2014 net merit to the 2010 version. Changes include semi-annual economic adjustments and the addition of two new traits: heifer and cow conception rate (HCR and CCR, respectively). Previous to this, daughter pregnancy rate (DPR) was the main fertility trait in the index. The addition of HCR and CCR will account for benefits not already included with productive life, such as decreased units of semen per pregnancy, reduced age at first calving, and other decreases in cost of reproductive management. Slight adjustments were made to production and fitness traits as well.
Use of selection indices, similar to net merit index, allows producers to compare economically important sires for their next generation of cows while considering where their milk goes and what premiums they may receive. Net merit is only one form of selection index available to producers, and other merit indices will be discussed in a subsequent article. Using an index really does make economic sense for the sustained success of a dairy operation. Selecting for single traits, like milk production or somatic cells, will only give you a fraction of the overall economic potential the next cow generation will have.
Source:psu.edu