So far, Genomic testing is being pursued in all breeds, but for assumptions of statistical reliability, are only being published in the Holstein and Jersey breeds. The larger data set for Holsteins is assigning “G” tested bulls 60% to 70% Rel on individual traits; for Jerseys a smaller data set is assigning “G” tested bulls 40% to 45% Rel on various traits.
We observe some dairymen (who trust data crunchers implicitly) buying individual “G” tested sires at premium prices, just as if they were truly “proven”. NOTE that scientist consensus at this point is to “sample” a group of “G” tested sires like you would have a group of young sires selected strictly on pedigree merit. This will be a safer approach, at least until we see progeny data on bulls being marketed from “G” estimates.
Taurus Service [Affiliated Sires] has published a directory of “G” tested young sires, and those are available to you upon request. We have selected a group of these sires to offer at package discount prices—you will find them quite sensibly priced, relative to the heavy promotional pricing we have observed from other sire development systems.
“CORRELATION” DOES NOT EQUAL “CAUSATION”
Genomic tested sires (the highest ranked of whom all appear related) have raised the question of the advantages of “linebreeding”. Here are some relevant thoughts:
Linebreeding possesses the same “risk to benefit” ratio it has always carried. When you have found or bred the animal you want, the most economical way to replicate it is to linebreed it-- except that, in the process, without careful mating balancing, you will at some point produce more extreme phenotypes.
It is the “extreme” phenotype—when “dairy” turns “frail”, when “tall” turns “narrow”, when “refined” turns “small”—where we see the negative results in fertility, health, longevity, and limits on production.
In Holsteins, as a result of older classifier resistance to accept more recent direction that a wider front end has longevity value, we seem to be reverting to “the narrower the better” view of what makes a Holstein “dairy” and ‘stylish”. (This was very evident in Holstein judging at Madison last fall.) We can expect to see continued problems with functional longevity from this “narrow” view of the “dairy” phenotype.
Extreme phenotypes are created when both the trait selection and mating processes shift from being an “additive” approach to a “subtractive” approach.
When we are additive, we develop matings in which we compensate; ie, width is added when we have reached our ideal stature; depth is added when we have our ideal length; substance is added when we have reached our ideal angularity; mobility is added when we have reached our ideal scale; and an elongation of skeletal extremities reaches functional limits dictated by the housing environment.
We shift to subtractive when we get enthralled by a visual representation of the current “ideal” fads and begin to make “likes to likes” matings—thus instead of having a “balanced” (level with topline) front end, we get enthralled with cows walking “uphill” [to show] or “downhill” [to milk]; instead of “level” rumps (which maintain a level udder floor) we seek more “slope; instead of “arched” pelvises (which provide the greatest calving ease) we seek “boxcar flat” rumps with tailsets sunk between the pins.
Focus on “stature” with “angularity” and you will subtract width, depth and spring of rib—leading to twisted abomasums.
Focus on high “peak” production with “angularity” and you will subtract body condition maintenance and cow fertility.
Focus on refined “bone quality” and you will subtract substance and stamina, thus overall adaptive ability.
Focus on narrow “dairy” front ends and you will subtract front leg mobility, replacing it with brittle bones and stiffness.
Focus on narrow “dairy” body and rear ends, and you will subtract forage feed efficiency and persistency in lactation.
The mating process that leads to our “ideal” is not a process of “like to like” -- it is a “what do I need to add next to get more improvement” process. It requires us to address the individual weakness that inhibits full performance from each animal, identify its causation, and match her to a bull possessing an ability to provide causative improvement. Thus, we gain function from an additive analyzation of the individual.
Statistical ranking indexes trap us in the fear that “I can only use the top sires across my herd, or I will go backwards”. This frame of mind lacks objectivity about the relative imperfections of animals we rank as “closest to perfection”. There is no “perfect” cow or bull, which is why none of them produce “perfect” offspring in reality– the “like to like” effect always results in an element of subtractive realization starting within all the traits and qualities not considered important within the index “ranking” formula.
Think additively when designing matings on your cows. Potential genetic improvement is only realized when we allow the better traits of the cow a chance to pass through to her offspring. The bull only does 50% of it.
When we look at PTA values for milk, bf%, pr%, DPR and SCS, we are seeing the effect of how that bull’s daughters are genetically programmed to ration nutrient energy.
It is a triangular PRODUCTION
Interrelationship: Volume (higher bf% and pr% yields
Components require more calories)
REPRODUCTION energy driven HEALTH
Calving vigor functions) Immunity
Fertility rate Body Condtion
In years past, most dairyman emphasized PD Milk (volume) as their primary selection criteria, followed by PTA Type (score) as their secondary selection criteria. “Milk” was emphasized for income gain and “Type” was emphasized for longer productive life. We only made one mistake—we defined a lack of body conditioning ability as “dairy”. Since then, we have suffered loss of timely fertility.
The advent of health and fitness traits (including DPR, a fertility measure) reminded us of the genetics of fertility. Trouble is, we are still milking cows whose genetics reflect the earlier, simplistic thinking. How do we breed back in the milk value, fertility, and health qualities lost from earlier sire selections ??
Understand the cow’s energy metabolism
High PTA Milk volume bulls, possess genetics that will short either “health” or “reproduction” to make the higher peak test days leading to the bigger ME lactation values on which the PTAs are based.
(example— one of the current leading Holstein “sires of sons”)
“Shottle” PTA +2165m (+.08% bf) (+.00% pr) 99% Rel ME daughter average 30245 pounds!
Health linked traits: 2.66 Somatic Cell Score Productive Life +4.0 months
Reproduction linked traits: -2.0 DPR 8.0% Dtr C/E 5.8% Dtr Stillbirths
“Shottle” while negative for DPR (cow fertility rate) is so positive otherwise on health and repro linked traits (SCS below 3.00) (Stillbirths below 8.0%) (Productive Life high plus), that he is more likely an example of “delayed” fertility (ie, breed back once gaining body condition*) than “slow” fertility, that requires lots of hormone therapy to get back in calf. This is consistent with his 2-4-3-6-1-5* aAa.
How “aAa” helps with energy rationing
Most sires who are more “sharp” (2-3-1) than “round” (5-4-6) in their mating qualities, will tend to be slower at gaining back body condition after reaching peak milk. You will find that if you keep the “sharp” (performance) and “round” (substance) qualities in your herd in balance, that reproduction and health qualities will improve—allowing them to express their genetic yield capability more profitably.
But if you wish to be sure, also consider the cow line evidence—for example, “Shottle’s” dam set a UK milk record in her fourth lactation (the average commercial cow peaks in her second lactation and leaves in the middle of her third). Thus she gives evidence of mature health, fertility and productivity.