“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.
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