Genomic Evaluations:  the next advance in genetics technology ?

$54 million is being spent on research into mapping the bovine genome (DNA) and identifying the SNP “marker” genes that indicate the desired direction in genetic traits.    It is an internationally funded effort but the work is being performed by Agricultural Research Service [ARS-USDA: same bureau contains Animal Improvement Programs Laboratory (AIPL) that calculates sire summaries and cow indexes.]    

What is an “S N P” ?

Single Neucleotide Polymorphism.    In other words, a DNA structure possessed by a breeding animal  that is able to indicate directional change in a trait.     We call them “gene markers” in part because we know they are linked to specific identified traits, and that they show up at the same location on the DNA no matter which animal possesses them.

How did we find them ?

AIPL collected DNA samples on over 6100 animals [mostly bulls with extensive AI service], and compared their DNA structure to their genetic evaluations for all summarized traits.    Patterns in common were summarized, and eventually 70,000 “links” between the data set and the microscopic views have been verified from 5285 of the samples.     [This from approx two million bovine genes.]

“It is hard to teach old dogs new tricks…”

Breed for type and feed for production.     I heard this so much from the breeders my Dad’s age I came to believe it.     That is, until I began milking my own cows, and realized that selection issues change as your herd performance evolves.     When we switched from Holsteins to Jerseys I learned some more… when we switched from confinement feeding to rotation grazing I learned even more yet.

Increasing numbers of selection traits adds complexity to interpretation.

Most of us grew up with production data and type/trait data.     We looked at production traits to gain on income and we looked at type traits to gain on herdlife.     The pace accelerated when composite indexes attempted to combine type and production into sire rankings.   As cow yield potential gained, negatives (calving difficulty, stillbirths, lower conception rates, mastitis, hoof diseases) seemed to accelerate just as fast.    Initially, geneticists blamed inbreeding (which proved to be a diversionary issue), then finally began to study health and fitness as “traits”—a process that continues to build momentum today.    The big shocker in the health and fitness trait studies was that  neither plus milk nor plus type is consistently able to increase herdlife.       Many still resist accepting what should make common sense, and delay changing genetic selection approaches for sires, detrimental to our future profitability.

There is more to success in breeding than just genetic rankings.

This article will expand your vision of herd mating for economic progress.

Y= BV + GCE + GEI

This is the sort of formula you will see in a college undergrad course on cattle breeding.   The Y stands for "Yield", as in volume of production, type score, calving interval, length of life, ie, any measurement in real terms that is the result of inherited traits and qualities.   The BV stands for "Breeding Value", ie, genetic evaluation trait measurements (as assigned to the dam and sire).    The GCE stands for "Gene Combination Effect", ie, the result of the specific mating tendencies of the dam and sire, also called a "mating effect" in some discussions.   The GEI stands for "Gene/Environment Interaction", which is an essential reminder that all measureable output is dependent upon the levels and limitations of inputs offered, and the geophysical environment within which the living organism must function successfully-- a domesticated animal's version of "survival of the fittest", otherwise called "adaptation" by biologists.