Wednesday, March 9, 2022

The impact of “aAa” (Weeks Analysis) on selection for fertility


“aAa” has always recognized the heritability of Body Conditioning ability.   This helps you to counter one of the major weaknesses in linear trait selection.

“aAa” accomplishes this by seeking more “balance” in the physical structure of the cow.    When genetic selection is so focused on “faster maturity” of the physique, by accelerating growth rate (the current simplistic method for measuring “feed efficiency” now built into “Net Merit” index) aAa balances young age growth rate with a sturdier bone structure and wider body capacity to slow feed passage through the rumen and abomasum to fully capture all nutrient energy so the cow can avoid falling into that energy deficit trap.

“aAa” keeps cows in proportional size, so they can adapt to your environment.

Unlike linear trait methods that use “rolling” genetic bases and have no anchoring to the limits your free stalls, alley widths, bunk spaces and parlor stalls place on cow size and stature, each cow is guided to a mating that can keep them within the scale of your existing facilities.

We all know that as cows have gotten larger (partially from physical maturity coming quicker; partially from that PTA Milk selection favoring bigger cows) and this trend has accelerated with more generations of “one size fits all” index selection, it has influenced many dairymen to get larger in order to build newer barns with more per-cow space.    It has also influenced feeding advisors to constantly increase the use of rumen bypass feeds to increase “energy density” but that runs up against rising ingredient costs in a “flat” milk price economy.    None of this would be necessary IF the mating methods employed could “manage” these genetic selection trends that have raised our costs with each successive generation of “high index” heifers added.

The impact of “cow line” sire selection for better fertility potential

Dr Allen Williams may be better known in the beef breeding world than in dairy, but his extensive studies in both have led him to conclude a dairy cow needs four calves before she is a “net profit” cow (recovered all costs of raising, producing at a profitable level).    This is one more calving than the “PTA Productive Life” index is based.      The biggest limitation in PTA-PL is coming from its reliance on “DPR” as the sole indicator of adequate fertility.    Daughter Pregnancy Rate data does not sort between natural heat conception and Ov-Synch fertility.

You will note that International Protein Sires, Triple-Hil Sires, and AI Total ALL have cow line type and production data in their sire directories.    Compare this to the many studs who only have “sire stack” pedigrees in their bull books…   where a majority of dams have not calved!      

Select sires on their maternal cow line evidence of realized fertility.
Mate cows so as to produce a balanced, healthy, adapted physique.

Breeding a more fertile herd is not “rocket science”, it is more (1) a consistent exclusion of sires who are no better than the average of commercial cattle, and (2) a consistent avoidance of matings that are highly likely to produce a heifer with more “extreme” physical proportions than your cow.

Sires are still available who offer exceptional ancestry of proven longevity, and the “aAa” method of mating can produce a more balanced offspring from their use.     You will find the semen prices on such bulls competitive, and you will also find that using “aAa” in place of genomic testing of (and sexed semen on) heifers is a huge savings.   

The production gain from functional maturity is greater than the marginal benefit of the highest PTA Milk values, and production profitability is also much greater at any level of current production you have attained.

Are you willing to be different from “the herd”?    Give us a call… (989) 834- 2661.

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