“Type” is a controversial subject in breeding, primarily because the industry has never agreed on one definition of “best type”. Earlier type classification was oversold as a way to insure healthier cows (primarily because cows with poor udders and crooked legs got lower type scores). Linear type was designed around characteristics of the fast maturing thus higher milk yield heifers, but within a decade the loss of fertility, rising cell counts and shorter productive herdlife became noticeable enough to create new indices (SCS, PL, DPR, CCR, CE and SB) documenting heritability of health and fertility traits.
The following remains true:
(1) Functional type trait deficiencies correlate with shorter productive herdlife.
(2) Lower Somatic Cell score indexes correlate with more sustainable mature productivity.
(3) Calving ease, stillbirth rates, and Daughter Pregnancy rates correlate with will to live.
(4) Productive Life results from a balance of underlying qualities, is not a direct selection trait.
Genomics procedures are a further level of “reductionist” science from our prior objective scoring. In type classification and linear scoring, a list of nine to sixteen traits is used to define the physical quality of each cow; sires receive PTA values by comparing these scores against parity age herdmates. After 40 years of linear scoring, we now have a Holstein that only averages 29 months lifetime production (2.25 lactations). In spite of health/fitness/fertility traits added 20 years ago, the average commercial lifetime is not gaining any length. With Genomics, a few preferred linear traits are being linked to a handful of marker genes associated with good trait scores in the reference population, and this is projected back into the linear type profiles and PTA estimates being published.
You can go too far with reductionist procedures to predict anything as complex as a living organism.
Ultimately, Genomics alone cannot control whether you get frail, narrow cows, beefy infertile cows, or any other dysfunctional variation. It predicts bundles of traits, at differing levels of accuracy (Rel%). It adds nothing to the need we have to produce “complete, highly adaptable cows”.
New DNA products (such as “Immunity Plus”) focus on individual pieces of the cow function puzzle, but the link between physique and performance is still mostly ignored—linear traits could not define it 40 years ago, and Genomics has not completed the puzzle today.
“aAa” redefines the focus of “type” so that form matches function. This is important because:
The best feed cannot nourish a cow who lacks capacity to eat enough for both production and repro.
The best foot trimming cannot heal a lame cow whose bones lack durability to stand on concrete.
The best calving ease sire cannot save a heifer who lacks openness in thurls and pins at calving time.
The best probiotics and antibiotics cannot cure a cow who lacks strength to maintain immunity.