There are few linear measurements available for feet and legs, and heritability of those measurements (usefulness to predict mating results) is quite low. In each generation of new heifers you find you still get cows who cannot walk smoothly, who have trouble getting into or out of free stalls, who go chronically lame or at least require constant hoof trimming—in spite of fifty years of selection pressure through “Foot and Leg composites” and other indexed measurements.There has to be a better way. And in fact, there is, once you learn to apply the concepts of physical balance to your matings. Focus on “function” rather than breed to the “average” of any trait measurement. Recognize the ways in which index selection leads to extreme physical results, and utilize individual matings to counteract that tendency.
Small steps to better mating, grazing, husbandry, and production. Musings from Greg Palen of Michigan Livestock Service and a "aAa" breeder.
Monday, May 16, 2022
Monday, May 9, 2022
Breeding for sound feet and legs
Since linear evaluation was introduced in the 1970s (fifty years ago!) the “experts” have argued from “you need a leg with ‘set’ in the hock” to “you need a straighter hind leg” without making any final decision. In fact, you can have too much set in the hock, or not enough: both become extremes that reduce the functional life of the cow’s mobility. A more important observation is that, when the selection index favors one or the other, within three generations you go too far. (Note that in Genomic indexing, the newest sires are already three generations past your cows in milk, so the functional defect can occur on two or even one generation!)
is more important—the LEG or the FOOT?
In the 1990s, one of the more important Holstein sire of sons was Walkway Chief Mark. Rising to the top of Holstein USAs TPI list on the basis of strong production and exceptional udder type he became controversial for producing a lighter-boned leg with a lot of “set” in the hock. Most of his AI sons ended up with big “minus” foot and leg composites, and this culled his decendant sire line from active AI. In spite of this, “Mark” and his best sons/grandsons were noted sires of high lifetime cows (the dam of Ked Juror for example produced 304,000 pounds lifetime, and the famous “Raven” cow exceeded 350,000 pounds…)
Overlooked in “Mark” was that he sired a pretty good foot. The shape and sidewall integrity of the foot has a huge impact on mobility. If a foot has even toes, if the forelegs track straight and the weight-bearing on the foot is centered (toe to heel) a cow can usually walk. If the hoof has a harder corneal shell, it will not wear to the point where the soft cartilage sole has to carry any weight (which leads to chronic lameness). If the front end has adequate width, the front feet will stand in a sturdy fashion, and will track straight when moving forward.
In observing hundreds of “Mark” daughters and granddaughters, the ones with leg problems were usually the ones with thurls in a “square” position. In other words, the thurl (hind leg socket in the pelvis) is back from an optimal central position, pushing pins up, forcing legs out behind the rear end, shifting weight-bearing onto the loin, which flattens-- bending the spine.
All the nerves that run rear end functions run through the vertebrae that shape the spine. To have long-term rear end function—hind leg mobility and presentation of calves—it is better to keep a spine in a straight line from head to tail. A central thurl will keep the hind leg under the rear end, supporting the rear-end weight evenly down to the foot, thus avoiding stress to the spine.
Linear traits have mostly ignored feet (only measuring low heritability “foot angle”) and remain fixated on the rear legs (straight or set hock? Flat/refined or heavy bone? Hocks in or out?) while totally ignoring front legs. There are wide differences between USA and Canada in how feet and legs are scored for linear type (the rest of the world’s type classification systems follow either the USA or the Canadian linear models). Thus we keep having foot and leg problems.
“aAa” analysis system breeds sound feet and legs
The first step: seek “balance”, avoid “extremes”
You have to perceive the overall cow in her physical completeness, asking the question-- “Does this cow have enough bone to support moving her weight around?” while also asking “Does she have ‘dairy’ bone quality, ie, is she a flat-boned ‘milk’ cow or a round-boned ‘beef’ cow?”
second step: analyze the
correlations of parts to the whole
Most linear type traits relating to extremities have lower heritabilities. This is because to just measure a “foot angle”, for example, ignores the shape and position of the attached leg which is connecting through the pastern joint. To effect any change in the physique we have to first identify causality: “what is making this body part look this way?” In this the leg is connected to the pelvic structure as well, its positioning controlled by the thurl and its motion actuated by muscles, nerves in the muscles, cartilage and tendons in the joints.
The third step: visualize the effect on overall function of any change in the physique
It achieves little if, in the process of “fixing” a leg or a foot, we choose a bull who in the mating is going to create a new fault in some other aspect of the physique. After all, the majority of cull cows are able to walk on a trailer to leave the herd. The cow with “bad” feet or legs may be more likely to “limp” on slowly than jump right in, but I think you get the point.
no matter how tight your selection focus may be on one or two linear traits, or
on a selection index, still involve combining two genotypes (male and
female) which exchange gene patterns in conception to produce a new
“mix” differing from both dam and sire.
Your cow is not a “blank slate” on which the mating sire will
automatically replicate his genotype.
All bulls will have good, average and bad offspring as a result of
the overall exchange of genes between your cow and chosen bull. Every mating changes the mix of genes
on every chromosome; it is not possible to just change “foot angle” or “leg
set side view” and not affect the whole cow.
The action step: match your cow to available bulls on the “balance” of the mating
Averages of studs do not matter at this point: You can only breed one cow to one bull at a time. “aAa” gives you a numerical coding covering the front end, body and udder, and rear end in the order of their importance to fix the faults. You simply find a bull who matches those numbers as closely as possible from the bulls you stock. His physique best complements your cow in the way that fixes the problems your cow expresses, while keeping the good parts intact. You get a more physically “balanced” result in the complete cow from each mating in this way.
Monday, May 2, 2022
Clay says: Steps to remember as we prepare for calving season
Do you expect some early calves that may come when weather creates damp,
cold conditions? We can provide
economical calf jackets to help a
valuable calf retain body heat.
Are you prepared for that lunker bull calf trying to be born from your favorite show heifer? Check your tack box: if you need calf pulling chains and handles we have them in stock.
Need protection from calf respiratory issues? We can provide Enforce 3 (administer at birth) which offers a “state of the art” level of vaccine immunity building.
Have you provided pregnant cows with free choice vitamin/minerals (block or loose)? If not, we can provide injectable Vitamin E (with A and D added) to help them get off to a good start.
If your animals (of any age) are facing feed transitions, we stock Conklin “Fastrack” as an oral paste, a dry feed topdress/additive, and as a “liquid dispersible” used on bottle calves.
As calves are falling, you may wish to check out the availability of both established and newer sires. We receive shipment from “Cattle Visions” every two weeks, beginning in the calving season. You can insure access to the higher demand sires with an early order.
Ordering your semen through us, pooling all your orders into full shippers, minimizes shipping costs per straw. We then absorb the shipping costs so you only pay the semen price.
We now have access to the S T Beef program, which has favorable prices on gender selected semen (mostly focusing on purebred bulls from all the major breeds).
For those utilizing seasonal storage of tanks and semen, just let us know the projected date for beginning your AI program in the spring: we will match to our delivery schedules. Any semen you wish ordered prior to bringing your tank, it will be placed in your tank directly from receipt, minimizing exposure to handling from UPS or Fed/Ex shipment. (We always add nitrogen into vapor shippers when they arrive, so straws are at the safest nitrogen temp. before transfer.)
Not certain your tank is still
holding up to specifications?
Each year we have a couple customers lose their semen from semen tank failure. If you doubt your tank, we can do a scale test here—there is still time to do this prior to the AI season. Clay also will check semen samples for basic motility (we have a new microscope) if you wish, given enough lead time to fit that into his busy schedule. Our goal is: one-stop full service.
Genetics today is really more “mathematical” than biological. “Population Genetics” is the collection and collation of “data”. The range of data, within a single environment, from any measurement suggests whether the trait may be influenced in offspring by “genetic selection”.
Heredity in a classic sense is more biological, ie, can we determine that a trait, a characteristic, or a behavior is based in the genotype? If so, can we determine its causal genes, and assemble (or delete) those genes from ancestry so as to maintain or eliminate them?
From year to year, you may observe differences within or across your cow herd and the calves produced. Is their success or failure genetic? There is a simple “rule of thumb”:
For example, If ALL your calves are getting pneumonia, that is an environmental issue (requires a manager intervention). If only SOME calves are getting pneumonia, while the majority of calves stay healthy, that could be a “genetic” difference (check to see who sired the calves with pneumonia, as well as which cows birthed them).
“Genetic” differences occur in two ways: the sire or dam is defective in that trait, OR, it is a mating effect (tendencies the sire and dam hold in common, brought forth from the mating).
The size of the “genetic” difference (as measured) can still be affected
by “management” as a result of inputs added or choices made. For example:
“John” provides creep feed to calves still nursing cows. “Joe” does not. “John” ends up with heavier weaning weights than “Joe”. The differences in weaning weight, once sorted by sires of the calves, within each herd, enter into the indexes for weaning weights for each sire. The differences between creep-fed and non-creep-fed calves may increase the range of weaning weights for John’s calves, but not for Joe’s calves; thus sires used by John may get a bigger kick in their indexes (which are a summary of deviations between calves and herdmates same age).
Genetics assume those differences between sires John uses will replicate themselves when Joe uses them as well. If they do not, they blame it on an Epigenetic effect (how genes alter their behavior according to environment differences or sudden changes).
The current practice of Genomic testing is to assign “genetic” (trait) values based on marker genes identified within the breed genotype as associated with traits already measured over a period of generations. Thus “values” can be assigned prior to measured performance. This is currently in vogue with the major breeds, but its lack of consideration for either mating effects or epigene response makes many cow-calf breeders question how much they can rely on them.
Pedigree ancestry for obvious reasons remains the basis of all “genetic” evaluation methods, even DNA mapping. We judge a bull by the performance of his offspring…