Saturday, May 13, 2017

Have we forgotten what a useful dairy cow looks like?

Many breeders who are pursuing high Genomic rank matings for AI and embryo markets are starting to question the type and physical proportions of many resulting heifers.   The phenotype of heifers (and their full brothers who often go into AI) seems to be like this:

        Around one third are too coarse (bully in front, narrow in rear) to milk well.
        Another third are too frail (narrow throughout, very fine boned) to compete.
        That leaves roughly one third that still look like a functional “dairy type” animal.
            (Yet we are assigning 50% Rel in Brown Swiss, 60% Rel in Jerseys, 70% Rel in Holsteins to these calves)

In the beginnings of scientific (mathematical) genetic evaluation, we compared a bull’s daughters to their dams, to see if the bull could improve on his mates.    The comparisons were made both for type and for production.    This approach resulted in development of “mature equivalent” (ME) factors to recognize that a young cow (first lactation bull daughter) was too immature to compete directly with a matured cow (third or later lactation dam).

This was known as “intergenerational comparison”—what changed from one generation to the next?
We still use intergenerational concepts in qualitative analysis (aAa or DMS), to predict results from possible mating choices.

But geneticists from early on preferred to seek the genotype (genetic potential) over the phenotype (realized result) believing that the phenotype was “too influenced by environment”.    Their first step was to convert sire evaluation to “daughters versus herdmates”, still using ME factors, and they called that result a “Predicted Difference” (PD).     This is “intragenerational” comparison—looking at all cows in the same generation, which logically led to the concept of “parity” (only compare daughters of our bull against other cows born the same season of the same year).    

The next step was the inclusion of the averages of the ancestors—first by “Pedigree Index” (1/2 sire PD plus ¼ maternal grandsire PD) which was assigned to both daughters and their contemporaries, so any deviations could be put in a “genetic” [pedigree rank] relevance.     By the time the “Animal Model” is inaugurated (pulling in Parent Averages for all animal pedigree relationships) we called the result the “Predicted Transmitting Ability” (PTA)  [actual deviation was only part of the total weighted data].

The industry was quite aggressive in promoting these indexes, which led to the composite ranking index ($Net Merit, TPI, JPI in the USA, LPI in Canada, BW in New Zealand, RWZ in Germany, etc).    All these indexes were designed to promote that nation’s genetics into any export market they could reach.

Now we have Genomics which looks at the DNA, but condenses the genotype to 64,000 “marker genes” that were possessed in common by animals who ranked for any measured trait in the historical reference list for each breed.     Now all we need to have a “ranking” animal currently is to find 7% or more of the markers in the DNA of your calf plus the pedigree ancestors to reinforce the assumptions (60% DNA vs 40% pedigree) to impute a high index.     We no longer “need” any progeny to get an elite ranking.

This might explain why there is so much physical variation in the individual high-ranked bull or heifer.
You do not need a “complete” or physically “balanced” physique to have the right “marker genes” to produce a high Genomic ranking value.     This is reductionist theory taken to its most extreme point.
                   How to still breed good cows for your environment

Not all Genomic sires are “the same”.   Some still actually have dams with scores and completed lactations.     Some actually have multi generation maternal performance to give us confidence beyond the mathematical assumptions.

And—as large expansion herdsmen are learning, type is still important.   Cows with a defective physique still leave herds faster than cows who have good physical adaptation to the environment.   The only issue with “type” is the basis on which you plan matings.

This heifer matured into a cow who made a lifetime yield three times that of the average commercial dairy cow (which at last count calves twice and milks less than 30 months).
She has the sharp shoulder and wide chest of the “sturdy” dairy cow, the deep and well sprung rib of the “ruminant capacity” dairy cow, the even proportioned udder with teat positioned central to each quarter on an udder with a level floor, and a rear leg position that fully supports her rear end weight, with springy joints, standing on substantial feet requiring minimal hoof trimming.   If you could add some more open space between her pins, she could have a more roomy rear udder (and likely calve easier) but this is a cow that will fit easily into any free stall space.

Mating should be on the physical, rather than a theoretical genetic, level if you wish to make cows like this one consistently.  Too many cows today are narrow, clumsy in their tallness, not able to maintain body condition, slow to breed, hard to calve.   Again, bulls do not need “balanced” physiques to receive a high genetic ranking.    The list of traits which add up to a high index is a short list that mostly ignores the physique.   

This is why we continue to bug you about considering the “aAa” method for planning matings that produce physiques capable of actually harvesting all that theoretical value the indexes promise (but are only able to deliver about one third of the time).

Some  current  favorites  from  newer  sires:

Two high production sires (progeny verified) who can safely calve your heifers:

99HO7070  Jehosaphat    (aAa 342156)               151HO 569  Pavethe way    (aAa 534126)
Use him on the smaller framed heifers                    Use him on the taller, narrower heifers
Calving ease:   5.9%     (5.8% maternal)                  Calving ease:   5.7%    (7.4% maternal)
+1060m   -02%   +35bf   -01%   +30pr                   +1242m   -01%   +41bf   -01%   +36pr
Carries the desired A2A2 Beta casein gene             Carries the desired A2A2 Beta casein gene
+4.1 Productive Life   +0.2 Dtr PG rate               +6.1 Productive Life   +1.1 Dtr PG rate
It is highly unusual to find sires (as these two are) who are still “plus” DPR above +1000m PTA
“Planet” son from a “Shottle” dam              “Planet” son from a “O Man” dam

Used within an aAa-directed mating plan, you can harvest the above genetic potential while also having a properly balanced cow physique that is capable of a full productive life without high maintenance cost.
Balancing the mating realizes more successful heifers than agonizing over linear profiles.   If you are afraid to use any bull without a “perfect” linear, you will end up producing tall, narrow, shallow cows—what linear classification techniques favor.    Think about that before you pass up any bull who has the production and daughter fertility and calving ease and developed maternal line gene support you need to change the “high maintenance” cow experiences you may have been getting.

Mich Livestock Service, Inc  “For the Best in Bulls”  ph (800) 359-1693

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