Monday, May 31, 2021

Concepts in linebreeding for in-herd use


Reference:  conversation with Jonathan Lambright, Indiana, June 29, 2020

Let us say you have a living cow in your herd who has done everything well so far: (a)  grew up healthy, (b) got bred on time and breeds back on time, (c) births live calves, (d) produces persistently, (e) has component value in milk with lower SCC, (f) heifers born to-date have been similarly healthy, reproductive and productive.

Biologically, this is a cow with a proven ability to adapt to your environment and to be economically useful under your feeding and marketing management.

Here is where considerations of your breeding goals  (is she the right color?  Is she polled?   Is she A2A2 Beta Casein and/or BB Kappa Casein?   Is she the desired size and scale to be a fit to your future environment?)  must be compared to what has been working for you across all successful cows.    Focus your goals in breeding.

At this point, you have proven phenotypic value.    How do we determine if she is of value genetically?     The first steps could be –

Raise a bull from a complementary mating: sell him to a neighbor, see if he does what your neighbor needs him to do (libido, fertility, health, quality of calves).

Raise a bull from a complementary mating: use on heifers in your own herd, see if he does what you need him to do, just as you would evaluate your neighbor’s.

In the meantime, any heifers she has had that you raised, consider how they are doing in your environment, whether “balanced” or “extreme” matings.   Hopefully she produces more heifers than bulls, as this seems to follow maternal lines.

Historical experience 

In the heydays of linebreeding (1920s-1950s) especially before AI made sire usage almost indiscriminate, breeders would test transmitting ability in this way:

Mate half brothers and half sisters together (linebreeds the cow)

Mate full brothers and full sisters together (linebreeds a cow x sire combination)

Mathematically, the mating of either half or full siblings is not “inbreeding” per se, as the theoretical percentage of ancestry “blood” from your focus cow stays at 50 percent in her F1 offspring, her F2 descendants, as many generations as you wish to go to perpetuate your focus cow’s influence.   

In each new generation, you need to evaluate:  are we making progress, are these linebred animals closer to my breeding goal than the rest of the herd, and are they giving me bulls that are successful mated across the rest of the herd?   If you don’t have positive answers to these questions, I would stop with that line.   A cow may have been exceptional in her generation, but that can be the result of being from a complementary mating followed by a favorable “genotype to phenotype” result within an environment that was conducive to success at each critical step.

When to outcross

When you linebreed, you will see that certain characteristics of your cow become dominant in her descendents, as a result of the homozygous pairing of genes that is occurring within their genotypes at each conception.    You hope to multiply the better traits of the cow this way, but you may also multiply the weaker traits.

This is where you seek (within your herd OR without) another successful cow, who is strong in the traits or qualities where your line is weak.    To avoid the random nature of a “cold” (pure) outcross, you breed this outcross cow to the best of the bulls in your line, and hope for a bull.    You evaluate and analyze any bulls born from this, and if they have the desired traits, you insert them into your linebred cattle to correct expression of the [weaker] traits in future generations.

In this way, you keep your line vitality while at the same time you gain uniformity and you keep your line competitive against cows from more “hybrid” matings you see as purely commercial producers (dependent on complementary mating and sire selection to produce useful replacements).    

Cow focus or Sire focus?

In Holstein breed history two examples of the above from the 1920s stand out as examples of how this can work successfully.

Carnation Farms,  Washington, USA

The Carnation Farms began their purebred Holstein breeding program around the “Segis” line, in particular a group of daughters from King Segis 10th.     He was a big spotted bull who sired a group of super-cows for the times (3x and 4x records up to 39,000 pounds of milk) that today we would call Strong, Tall and Style (aAa 4-2-6).    Sons of these cows sired by “Homestead” line bulls were used and a bloodline developed, good enough that this breeding crossed the country to be herd sires in both purebred and commercial herds seeking milk volume.

The weaknesses that developed were primarily (a) cows too big for midwestern stancion barns, (b) lower butterfat % test, (c) large teats, not adaptable to newly-invented milking machines.   

To solve these deficiencies, they bought a bull at public auction who was a yearling son of the new world record butterfat Holstein (1300 pounds with 4.7% test) whose udder had four teats squarely placed under an udder with level floor.    This bull was the desired mating for linebred Segis cows at Carnation Farms for years (he lived to be 21!), providing Dairy, Smooth and Open qualities (aAa 153) that modernized the big, rough, titty Segis’.    An efficient size bull and a sire of desirable feminine refinement, he transformed the Carnation cattle into their own bloodline (bull books of the 1950s-60s referred to them as “Carnation Homesteads”).    Basically they linebred the King Segis 10th x Sir Inka May *RC cross.  The “Red Factor” was discovered after some sister-brother Inka crosses had been made, initially a liability, eventually an asset as it is calculated that EVERY Red Holstein in North America descends from Sir Inka May.

Mount Victoria Farms,  Quebec, Canada

The owner of Mount Victoria had prior experience developing some of the first hybrid seed corns.   He began this herd with “Colantha” cattle that were Open-ribbed, Dairy, and milky but needed higher butterfat % test.     They found Johanna Rag Apple Pabst in Wisconsin, who was 25% “Colantha” and 75% “Korndyke” breeding, so a ‘warm” outcross to the foundation cows.

First they prevailed on the sellers of the bull to breed his own daughters back to him, in order to see if there were any hidden recessives.    Among the six inbred heifers produced, one was first prize two-year-old at the Royal Winter Fair (Canada’s national show) and another set the two-year-old butterfat record at 725 pounds 3x (pretty good for 1929).     JRAP daughters were bred to JRAP sons; in the following generation, double granddaughters were bred to double grandsons; a strong pattern began to emerge, meeting Mr Macaulay’s initial goals: healthy cows with modern udders for machine milking, testing over 4% butterfat, expressing longevity.

After Mr Macaulay died in 1942, in the early days of World War II, his herd was dispersed, but the buyers across Canada and into northeastern USA continued to linebreed the “Rag Apples” as they became known, and such herds persisted into the early 1970s.    One such herd (Ohio) the Owens family, milked 300 linebred “ABC” Rag Apples (ABC Reflection Sovereign) into the highest herd average for herds 250 cows or over in Ohio for several years, and linebred to JRAP descendant (“ABC” son) Rosafe Citation R *RC for as many as eight generations of “Citation R” sons in a row with no loss of productivity.

How  to  avoid  “inbreeding depression”  while  linebreeding

I used the term “compensatory mating” early on, and the most evolved system to accomplish this is the “aAa” Breeding Guide (Weeks’ Analysis).  

While inbreeding per se is a mindless mathematical calculation of percentage of related ancestry in the bloodline, this is an inexact and misleading way to predict “inbreeding depression”.      In biology (reinforced by what we have learned in Genomic measurement of the DNA) we know that all genotypes are individual, the result of the combination (pairing and discarding equally) of a sire and dam DNA at conception.

These genes do not flow equally from ancestors to descendants.   Lot of genes will disappear within as few as three generations.     Genes do not “dilute” (averaging of effects) within pedigree descent, they “pair” up, so it is easy to understand how they disappear.

The effects of inbreeding “depression” are all physical deficiencies so the practical way to avoid these effects is to plan matings around compensatory qualities.   aAa measures these according to the skeletal and soft tissue character of the physique and with a goal of physical “balance” between production qualities and substance qualities that support and extend functional life.    

Analyze your foundation breeding stock each generation

Because each conceptus is “individual” there will always be variation even among full siblings.   You can use this individual variation to avoid making “extreme” animals with lower functional quality as you pursue following generations of related animal matings.    The “aAa” process is consistent in identifying the transmittable physical character of each breeding animal, and as you match up cow and bull physiques for matings, you maintain a constant level of “heterosis” in phenotypic expression that helps you avoid the “inbreeding effect” of random matings; we tend to favor what we like and discard what we do not understand as having compensatory value, so linebreeding without “aAa” can lead to the decline of your line into more extreme or deficient physiques that are not adaptable to an ever-changing external cow environment.

Function follows form.    

You may have chosen your focus cow in part on the superiority of her physique.    However, as no animal (cow or bull) is ever “perfect”, maintaining compensation in mating qualities allows the good traits that led you to choose this cow as “foundational” to be expressed positively in the resulting generations of offspring.    

The option of embryo transfer

Lots of decent cows have become famous through the expense of multiple-ovulation embryo transfer, with breeder promotion focusing on the successful matings.    ET could be used as a faster way to “test” the transmitting qualities of a cow, and if there is little consistency in the offspring produced, you know sooner that this is not a worthy foundational cow.      

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