Friday, June 19, 2015

A Contrast between “new technology” and Time-Tested Selection

From the July August 2012 Dairy Newsletter

Prior to the advent of Genomics, selecting sires for AI sampling was a combination of pedigree review, physical inspection, and thorough analysis of the maternal cow line against the chosen mating sires.   In this, no AI system today is more thorough in screening maternal lines than International Protein Sires.

Among cow lines, one of the most enduring is the “Roxy” family (descendants of Glenridge Citation Roxy--  EX-97, Gold Medal Dam, All-American and All-Canadian show cow).     There are now over 135 “Excellent” maternal descendants of “Roxy” worldwide and up to 14 consecutive “EX” generations through one of her many “brood cow” daughters.   This is a “maternal traits” line, more about fertility and longevity than “fast-maturity” young cow production.     But lightning can strike at least once.

Qualifies top 20 TPI on production (82% Rel), needs a few more daughters scored for type (69% Rel)

6HO 1126  Brigeen ROCKWELL –ET         aAa: 2 3 4 1 5 6     “Tall + Open + Strong + Dairy”

+2068 TPI   +1920m  +07%  +90bf  +01%  +60pr    3.05 SCS   -0.2 DPR  -0.2 PL    $496 Net Merit
7% calving ease  (7% daughter calving ease)   +2.18 PTA Type  +1.21 Udders  +1.97 Feet and Legs

Note: the above is all progeny (and pedigree) based data, as “Rockwell” has not been Genomic tested!  (A quirk in the rules of the research—the contributing AI studs have a five year monopoly on G testing of bulls;  IPS was not yet in business in 1992 when the Genomic dairy research project began).

Sire stacks dictate the initial range of PTA values, but maternal cow lines can promise exceptions

“Rockwell” is the #1 TPI son of his sire “Toystory”, but his initial ratings for fitness traits suffer* a bit from this sire stack:   Toystory x Morty* x Convincer* x Emory x Integrity* x Prelude x Southwind ( x Apollo Ivanhoe x Citation R x Treasure Model x Roeland).    It takes really high Rel% to wean out the Parent Average assumptions built into “lower heritability” traits.

But when you consider the quality of “Roxy” cows in his pedigree:  EX 92 x EX 95 x EX 92 x EX 95 x EX 91 x VG 88 x EX 94 x EX 97 x VG Canada x EX Canada—and the first four added up to over one million pounds actual lifetime production (without rBST)—“Rockwell” has an exceptional inheritance.

Does new technology make proven technology obsolete over night?
The success of “Rockwell” would argue NO.     In fact, as a dairyman, your milk check is still based on actual progeny performance—not on imputed genetic value.     Breeding a profitable herd of cows still results from using reliable genetics for sires, mating cows carefully, and avoiding narrow (single trait, single index ranking) selection procedures.    Breed for an improved herd with “real” economic values.  

Who  has  the  emerging  “genetic  giants” ??

Taurus Service’s “EXPLODE” could have been #1 TPI in April.    International Protein Sires’ “ROCKWELL” could have been the highest milk solids yield of TPI ranked sires.
The world of Holstein breeding is going to pay attention to these two sires.

For decades, large AI systems have dominated TPI and $NM rankings by virtue of large sire sampling systems.    But with the advent of Genomics this playing field has leveled   a bit, while focusing more on what index selection overlooks that remains important for dairy profitability brings more uniquely usable sires to the forefront each generation.

Inside, we tell a story of two new Holstein bulls—but the contrasts in their path to value apply to any breed (as well as crossbreeding), as finding genetic value is defined by the approach you take to harvest the gene traits and qualities that can add to your income.

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