Genetic indexing is based in the commodity definition of milk value, not in specialized genotypes that optimize our ability to capitalize on premium milk markets. This needs to be recognized by dairymen, as soon as they pursue specialty milk markets that increasingly include specialized land, feeding, animal, and processing protocols.
Thus, while Genomics has been all about condensing the selection mechanisms to a reductionist scan of the DNA for marker genes specific to commodity value production and only imputes index estimates for the AI sire selection process, dairymen increasingly are seeking information that goes beyond the basics of additive trait statistics.
Dairymen have tried crossbreeding as well as linebreeding. They have limited their sire selection to sources with similar farm management (as in graziers only using New Zealand grassland bred sires). These are all a reaction to the inefficiency of the selection (“ranking”) index to produce the cows needed to meet your goals. Over time, all indexes have this weakness, mating “likes” to “like”.
There may be a specific gene, as with polled heads or A2 Beta Casein or specific selection traits, as with plus butterfat% and protein% deviations or plus Productive Life that become absolute requirements. In each of these cases, there is a relationship to the milk market and to farm management parameters that dictates these genes as more important than the composite index the AI industry uses to “keep score”.
Matrix selection makes more sense (than index rank) for any specialized management or market.
A “matrix” is basically a list of “absolute” traits and qualities you wish each mating sire to possess. If it is a longer list, you may settle for sires who possess 75% of the desired characteristics. But the point is that rather than trust a composite index that “averages” the good with the bad to create a ranking biased by an external view of what is important, you work with bulls who avoid faults you wish to eliminate from your herd while providing the traits you need for your market and future market.
If you are seeking to participate in any direct milk marketing or specialty milk classification, genetic ranking as we currently practice it no longer applies to your situation.
Why do we continue to produce “frail” heifers in spite of culling “frail” cows ?
This is another aspect of index dependence. The more generations you follow a single index, the more “inbred to the index” your herd becomes. In the case of TPI, LPI and $NM, it is in physical aspects of the animals that we create limitations for health and productivity even as the indexes are formulated to include trait measurements in favor of health and herd survival.
The conclusion of many of us is quite simple: the heritability of qualitative physical characteristics is clearly greater than the heritability of trait measures for health, fertility and herdlife. While you are adding up pedigrees full of PL, you are raising physiques that are too fine boned, shallow and narrow to function as they reach maturity. Thus we continue to cull more cows in third lactation than we did in first and second lactations, leaving so many of us needing every heifer we raise to maintain herd size.
“aAa” will better explain why matings to highly ranked sires do not produce longer herdlife cows.
Are you ready for what could come your way in the milk market?
First it was component pricing, which made selection for +bf% and pr% more important.
Recently it was a lowered SCC standard, which makes selection on SCS more important.
Next, to be proactive in the face of consumer activism, but more importantly for impacts on calf growth and labor efficiency, selection for polled heads has become important.
What is next? It could be A2 Beta Casein. Just as was true for the earlier evolutions in dairy breeding, we are prepared with knowledge to advise on this potential premium milk market. The desired trait can be found in a useful cross section of the major dairy breeds already, thus the usual arguments “but this interferes with genetic progress” will be as meaningless as they were for all prior issues that changed the direction of mating selection.
Our breeding program has two focuses: (1) mate cows for more adaptable replacements, (2) select on traits that enhance current profitability and future marketability. Thus it is NOT a commodity “one size fits all” breeding philosophy or sire list.
Mich Livestock Service, Inc “For the Best in Bulls” Since 1952 your independent AI source
Physical character of “frail” (short herdlife) cows
Every herdsman has a personal definition of the ‘frail” cow—half of it is behavioral and half of it visual. Frail cows are culled every day, but keep reappearing in the heifers we raise to replace them. To avoid producing new “frail” cows, we need to understand how they get “mated” in the first place.
The limitations of the physique define the potential behavior of frailty
What does the “frail” cow look like? Usually she is the cow who looks like she is working hard. In other words, she has a lighter boned frame and very spare muscling, with lower body condition scores.
She may have a shallow body; she may have a narrow frame from head to rump. Her respiration will be more rapid as breaths will be shallow. As she matures, the pace of aging appears rapid, with udder deepening and movement stiffening. The cow may be slower about cycling and rebreeding after each calving. She literally “milks herself to death”, if not lost to injury from clumsiness or repro failure from lack of body conditioning. Note: her “genotype” has given her this “phenotype”.
The above describes the “all sharp weight” ( aAa qualities 1+2+3 ) dairy cow physique
The qualities of the skeleton (bone) and the soft tissue (muscle, cartilage, tendons, nerves) are heritable on a very basic “qualitative” gene level, alongside the glandular functions that influence both skeletal and soft tissue development. These underlie the more surface expressions of individual linear traits on the “quantitative” gene level, on which geneticists (and sire analysts) focus for their relationship to the productivity of the animal.
In “aAa” observation, the “sharp” qualities of (1) dairy, (2) tall, and (3) open produce more refined bone and feminine spread of the pelvis; a faster growth rate for long bones, resulting in lean muscle mass; and a minimal, elastic connective tissue between the bones. The dairy metabolism is oriented to more will to milk, the tall metabolism is oriented to faster maturity, and the open skeletal structure is oriented to more persistent production during pregnancy. Thus, in comparative genetic evaluation, the “sharp” qualities provide advantages in responding to feed energy density, a faster physical maturity, and sustained milk yield after rebreeding, that translate into bigger “plus” PTA yield volumes, especially at immature lactation ages.
Performance physiques require supporting “substance” qualities to stay healthy and live
These same qualities, when intensified by multiple generations of selection in their favor, reduce the adequacy of “round” qualities that provide substance, stamina and fluid mobility. Thus, the size and ability of the heart, the rumen, the liver, the uterus, ie, all internal organs, to meet their functions, as is being dictated by the genotype’s production gene possession, is dependent on maintaining a level of “round weight” ( aAa qualities 4+5+6 ) to support and sustain the drain of nutrients from the physique of these “sharp weight” quantitative gene actions.
Lacking one or more of the “round” qualities of (4) strong, (5) smooth, and (6) style, sets a cow up to have more troubles with circulation, flushing toxins from udders, swelling of joints, poor respiration, hyperventilating on hot or humid days, sturdiness of stance, uneven wearing or growth of hooves and related lameness, maintaining body condition, the fluidity of leg motion, getting up and down in stalls.