The Holstein
breed proved to have the most genes for “metabolizing corn into milk instead of
weight gain”. The Red color breeds
(Shorthorns, Ayrshires) had the least similar genes-- and those smaller frame
breeds (Jerseys, Guernseys, various heritage breeds) lost persistency if fed
higher corn/oilseed rations, but were mainly condemned for producing “too much
butterfat” given government nutrition advice based on bad science from the corn
and soybean lobbyists aimed at convincing American consumers to substitute
vegetable oils for animal fats.
Thus in the
1970s there was wholesale crossbreeding of “colored” cows with Holstein
bulls and the national butterfat average fell from 4.02% (1945) to 3.69%
(1966), staying under 3.65% for four decades as a consequence of
“Class I bottling milk” premiums and AI “PTA Milk” emphasis. Today with the combined effects of
multiple component pricing in the northern milk orders, and noted growth in
consumer demand for butterfat products
(including “whole” milk is replacing “skim” in modern nutrition advice to
control weight) accompanied by
explosive yogurt and hard cheese sales, the national butterfat blend has
reached 4.08%. In spite of this, the USA imported over
105 million pounds of butter in 2012, over half from Ireland (where cows still graze grass and produce
premium taste butter quality).
Breeding
for ever more butterfat to keep up with consumer demand
You are in
luck, because the highest selection traits in heritability are lactose %,
protein % and butterfat % in that order (twice the level of heritability for all
linear type traits except Stature, and three to four times the heritability of
most promoted DNA “health and fitness” traits!) In breeding for increased butterfat and
protein production, genes will accumulate fastest if you focus on sires “plus”
more than .05% for butterfat and .03% for protein.
How
important is “pounds of milk” in your sire selection? According to the calculation for “Net
Merit” index, not much. If
your milk goes through MMPA, they will tell you otherwise, mostly because their
key handlers are bottlers, not cheese or yogurt processors. Most bull studs still push “pounds” over
“per cents” because they are still overcoming a four decade selection trend where
indexing formulas remain built upon history rather than the future.
But a key
problem with the decades of genetic selection on “high milk” was its high
correlation to the promotion of “high early lactation peak production” which
1970s scientists identified as a key characteristic of the cow who could eat a
corn-based ration and make milk instead of meat. This type of cow (and genetic selection) is
what held butterfat down to 3.65% in spite of twenty years of breeding
advice “ select on pounds, not percent “ and was accompanied by reduction
in natural cow fertility. Basically,
cows who peaked the highest, shedding the most body fat, converting rumen
proteins to body energy to keep alive, delayed reproduction as long as they
were in persistent negative energy states. Increased feed costs are the required
solution.
Extraordinarily
high lifetime production cows have “flatter, more persistent” lactation curves
If you are
struggling with fertility, spending $200 per cow on “Ov Synch” to get 80% of
the cows rebred, selling 20% annually for failure to rebreed, it is this fifty
years of genetic selection for a high peak milking cow designed to eat high
energy dense corn and oilseed rations.
Very little genetic research has gone into comparing the correlation
between flatter lactation curves, full persistency (from calving to dry off)
and its correlations with better “natural” fertility response.
Many have
found that, on dollar value of milk sold per cow per day, a persistent 80-pound
cow testing 4%+ butterfat and 3.2%+ protein, calving back every thirteen months
beats a 120-pound peak cow testing 3.7%- butterfat and 3.0%- protein calving
back in fifteen to eighteen months!!
Translated into sire summaries, this is the possible difference between
bulls +200 to +500 milk but +.10% bf and +.05% pr and bulls +1500 to +2500 milk
but -.10% bf and -.05% pr…
From a
physical traits standpoint the Holstein bulls offering aAa 1 + 5 + 6 (currently
discouraged by the pedigree-based Genomic selection) are more likely to help you with slow
fertility genes.