For over twenty years USDA-AIPL and now CDCB have been publishing Net Merit (NM$) values for dairy cattle with US genetic evaluations.  Over those twenty years five revisions have been made to the formula, the last in 2010, as new traits have been added, new genetic evaluation methodologies have been developed, and the economics of dairy farming has changed. The next change in the formula will occur in December 2014.

It is important that breeders consider the impact of the coming changes as they review the sire, cow and heifer NM$ indexes on August 12th.  Breeder consideration is needed because the matings that are made this fall will have offspring born in 2015 when the new formula will be in place. Obviously the changes in the formula will not affect how the new future animals will perform but it will, however, affect where the animal ranks for marketing purposes and where a herd’s genetic level for NM$ is relative to other herds.

Let’s dig deeper and see what changes are to take place and how that may affect current breed leading NM$ sires.

Significant Changes Coming In December

The following table compares the weightings, 2010 to 2014 (December), for the components of the NM$ formula.

TABLE 1: Comparison of Relative Emphasis for Traits in NM$ Index

DE-SU OBSERVER-ET16027.22.7667922.73.020.892332
HONEYCREST BOMBAY NIFTY-ET2367.22.627553-0.46-0.130.971810
POTTERS-FIELD KP LOOT-ET10047.22.6876500.081.71-0.241954
KELLERCREST BRET LANDSCAPE817.12.3685060.651.271.161838
WHITMAN O MAN AWESOME ANDY2026.92.5557540.32-0.171.212063
ZIMMERVIEW BRITT VARSITY-ET4106.82.6266680.71-0.471.552013
CLEAR-ECHO NIFTY TWIST-ET9426.82.628748-0.32-0.421.172039
KED OUTSIDE JEEVES-ET3556.82.83105151.370.971.741913
ENSENADA TABOO PLANET-ET22166.72.9867211.931.44-0.472176
GOLDEN-OAKS GUTHRIE-ET10786.72.786535-1.15-1.240.361728
DALE-PRIDE MANFRED ALFIE5196.62.966461-0.63-0.36-0.011702
LAESCHWAY JET BOWSER 2-ETN2006.52.8474551.622.031.831940
ELKENDALE DIE-CAST-ET-8726.52.7263700.681.851.991718
LAESCHWAY JET BOWSER-ET2006.52.8474551.622.031.831940
BADGER-BLUFF FANNY FREDDIE12366.42.757791.571.62.872292
CABHI AUSTIN POTTER-ET1516.42.8165200.050.410.021766
CABHI MOOSE-ET456.42.6463730.180.31.111625
SILDAHL JETT AIR-ET11186.32.6466442.882.262.912168
SPRING-RUN CAMDEN-676.22.9174330.571.790.61762
KERNDT MAXIE GOLDSTAR-ET1996.22.576449-1.28-0.61-0.961631

Thoughts on the changes include:

3 Proven Sires Favored by New Formula

Three currently (April 2014) high NM$ proven sires will gain from the new formula. They are: Roylane Socra Robust; Den-K AltaGreatest; and Mainstream Manifold. They are all high production sires, and the new formula will favour them. All three, Robust, AltaGreatest and Manifold will also benefit from less emphasis on their average traits – SCS and DPR.

Breeders can expect to see sires that have production indexes below 1500 lbs for milk and 65 lbs for fat drop relative to other sires for NM$. Sires over 2200lbs milk, 80 lbs fat and 55 lbs for protein will rank higher for NM$ come December 2014. Breeders that use NM$ in sire selection should consider discontinue using, after August 12th, sires with low production indexes.

2 Genomic Sires Going Up!

Two currently (April 2014) high NM$ genomic sires will be rated higher with the new formula. They are: Cogent Supershot; and Uecker Supersire Josuper. They are outstanding for production. Supershot – 2528 lbs milk, 100 lbs fat and 85 lbs protein. Josuper – 2971 lbs milk, 118 lbs fat and 92 lbs protein. Supershot has good ratings for the other traits so will remain to standout for NM$. Josuper will benefit from less emphasis on traits where he is breed average.

Many current relatively high ranked NMS genomic sires will fall back if they have only moderate milk indexes.  Breeders should consider discontinuing the use of genomically evaluated sires below 1600 lbs milk, 85 lbs fat and 60 lbs protein.

The Effect on Polled Sires

Current marketed polled proven sires are not highly rated for production, so will not fair well with the new NM$ formula. On the genomic sire side, two high production sires standout as sires that should increase in their relative NM$. They are Bryhill Socrates P (1914 milk 99 fat and 65 protein) and Pine-Tree Ohio Style P (2033 milk, 64 fat and 57 protein). Other sires that will do relatively well under the new NM$ formula are Kerndtway Eraser P, Da-So-Burn MOM Earnhardt P and Pine-Tree Ohare P.  Many polled sires have below 1000 lbs of milk and can be expected to drop significantly in NM$ come December.

1 Star Sires of Sons

One sire of sons stands out as benefiting, in a significant way, from the new NM$ formula. That sire is Seagull Bay Supersire. His high production numbers put him in an elite status – 2434 lbs milk, 111 lbs fat and 78 lbs protein. The reduced emphasis on SCS and DPR, in the new formula, will also help Supersire, as he is average for those traits.

Other genomically evaluated sires of sons, heavily used over the past couple of years, often have been only moderately high for production traits. Included in this category are sires such as Mountfield SSI Dcy Mogul, De-Su BKM Mccutchen and Amighetti Numero Uno. These sires do have some outlier high production rated sons but, on average, the majority of their sons will drop for NM$ come December.

Be Prepared to Avoid Inbreeding

With both Robust (sire) and Supersire (son) in heavy use and both benefiting from the new NM$ formula, it will require that top outcross sire and female lines be identified and used in order to avoid inbreeding. That can be accomplished by breeders using both corrective mating and genomic testing.

The Bullvine Bottom Line

The changes coming for the NM$ formula in December 2014 are not just minor tweaks. Breeders that use the NM$ index in sire selection should be prepared to set aside sires that in the past have had high NM$ ratings but were only average to slightly above average for their production indexes.

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