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.
No comments:
Post a Comment