The previous generation of dairy geneticists who gifted
the world with the “selection index” must be rolling in their graves. These were the fellows who actually told us
“just breed on Net Merit ranking and all your other problems will go
away.” At that time “Net Merit” was based
70% on PD Milk and 30% of PD Butterfat—no protein, no type, no fertility, no
health trait measurements. All those
things were added after the cow population began to suffer in all of those
areas (some of which those same geneticists tried to claim were “management”
traits rather than heritable behavior, as we now know them to be).
Consistent through all the formulation
and recalculation and creation of new measurements (some of which are quite
arcane, perhaps less than 5% heritable) – the advice was always, “don’t focus
on some specific list of traits, just let the selection index do the job”. Indexes were promoted as “more efficient”
than a dairyman making his own list of desired traits and setting minimum
levels of trait expression he would accept—a practice known as “matrix” selection.
For the 55% of dairymen who still use
a “matrix” approach, the latest advice – “calculate your own index” (according
to the needs of your current herd) – is a vindication. So as not to offend their old college profs,
these new geneticists just avoid the word “matrix”. But in fact they are now telling us,
“composite index selection is obsolete” (even though these are the basis for
all sire selection being done under Genomics, which are calculated purely to
the various national index formulas).
Just ask Nate Elzinga of Zeeland, MI, one of Michigan’s
most milk productive dairymen, how he chooses his sires. His office computer is programmed to
recalculate the data from every sire AI offers him, to the weighting of traits
he devised matched the heritable traits he wished to address in his herd of
cows. Or ask Josh DeHaan of Wayland,
MI, how much he was able to accomplish in improving all fertility
characteristics of their expanding herd by a focus on health and fertility
traits alongside matings to create balanced physiques. Many of your neighbors may be requiring plus
bf% and pr% traits who wish to raise their milk price and find they are $2.00
per cwt above their breed average after only two generations.
The famous Wally Lindskoog of Arlinda
Farms, Turlock, CA shortly before his passing told an interviewer that he could
see the future of AI developing many specialty AI companies, whose sire
selection would not be based on an ”index” but on the genetic preferences of
like- minded dairymen of similar geography or facility design and milk
market. We have seen this process
occurring ever since Alta Genetics purchased Landmark Genetics.
How do you design your own herd
index?
First, you look at your own economic
and management data. What elements of
cow care and management are costing you the most? Focus on whatever heritable measures may
have an impact on those issues. For
example, if conception rates are an issue, then establish a minimum
trait value for daughter pregnancy rate (not semen conception rates,
which have no impact on your cows’ natural fertility capability). If you lose too many calves at birth look
at stillbirth rate; if you lose too many heifers to hard calvings, look
at both sire direct and daughter calving ease. Establishing dollar values for each of
these types of financial loss helps to put all of your herd data in perspective
of where genetic change could help.
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