Monday, December 26, 2016

Logical Type: when "form" follows "function"

By Greg Palen

“Type” has always had an impact on genetic selection, going all the way back to the “Guernon” system (prior to milk testing and show judging) which studied the patterns of hair over the rear udder in the 1800s.     As the milk industry evolved, “type” was to discern “dairy” quality from “beef’ quality.    The breeds then developed the judging scorecard to visualize the superior cow in show ring comparisons, followed by the “descriptive type” classification era which defined traits with the longest lifetime potential.     In the 1970s, defining “type” was turned over to the university geneticists, who designed linear traits appraisal to identify faster production maturity in cows at an early age.      As you can see, views of type continually evolved, at least until the breeds let reductionist scientists take over.

Type can be viewed broadly or narrowly

In the Beef breeding world, two standards of “type” exist—the characteristics of the fast growth “performance” animal, and the easy calving “maternal” animal.    Basically, the beef breeder is painting cattle physiques with a broader brush, not ranking animals on individual structural parts but on the blended result of the whole, selecting animals for breeding according to their purpose (wide and deep type to produce momma cows, long and tall types to hang steer carcasses).

In the Dairy world we have spent a lot of effort measuring individual parts, first deciding if they relate to production, and usually at the expense of assembling them into an integrated physique.   We will, for example, castigate an otherwise useful bull for siring “low foot angle”, when no one has ever culled a cow on the basis of foot angle.    We argue over whether “posty” hocks or “set” (curved) hocks are better, when neither one answers the question in comparative function (again, cows leave herds too early possessing either trait, cows live long lifetimes possessing the same).

The conceptual basis of type will control the success of the result

If there is one overriding concept within “linear type” it is that angularity trumps all.    If a dairy cow possesses visible substance (good body condition, heavy bones or muscles, more wide than tall, more long than deep) she tends to go down the scale in linear scoring.    The high production heifers of the 1970s were the most “angular”, therefore 45 years later (when cows are no longer hand fed in stanchions, but muscle into feed bunks, when they must walk wet concrete alleys and sleep in free stalls) we still insist on the same angularity while expecting 50% more milk per day than we accepted in the 1970s.

If we were to challenge this concept of “type” we could point out 45 years is 10 to 15 elapsed cow generations (“Cows have changed since Hoover was President”).    The highest producing heifers today are better grown, taller and bigger  than their 1970 counterparts, while the longest production life cows are more “dimensional” (wider, deeper, longer) than their ancestors’ 1970 contemporaries.     But all along this continuum of type measurement concepts, it is our lack of grasp of the multiple functions of the cow physique that create the limitations of type’s utility.

What do we expect of the cow?    (1)  We expect her to grow efficiently from calf to breeding heifer to freshened cow.    (2)  We expect her to calve easily and then get up to care for her calf.   (3)  We expect her to adapt quickly to each new life event, including being milked.   (4)  We of course expect her to milk in quantity when fresh and maintain a persistent volume of milk once rebred.     (5)  We expect her to maintain enough body condition and intake enough feed that she will rebreed in an efficient interval of time.    (6)  We expect her to walk on concrete, lay in free stalls, seek the feed bunk and stand there until full, be sure enough on her feet to mount and be mounted for visual heat detection, avoid injuries to teats and udder tissue when getting up and down.    (7)  We expect her to stay healthy no matter the climate (cold, heat, humidity).    

Careful review of these suggests that all are closely related to (if not dependent on) qualities of the physique.    Thus, “type” is important, but the method of defining “good type” more relevant to producing and replicating adaptable and profitable cows.

“aAa” Breeding Guide—the comprehensive relationship of “form” to “function”

Bill Weeks, first as a herdsman, then as a classifier, ultimately as a purebred Holstein breeder, dedicated his life thought to studying the mammalian structure, in the relationship of body parts to the organic living whole, and the interrelationships of body form to biological and economic functions.      His first epiphany was to blend “sharp” (skeletal qualities) with “round” (soft tissue qualities) to produce an “expansive” rather than a “restricted” physique.     His second epiphany  was to connect “behavior” to the physical qualities present or absent.      His third epiphany as a result of observing the “blended qualities” in “aAa” client herds was to identify causality in trait problems with the absence of one of the six “aAa” qualities defined from sharp and round in the front end, body or rear end of animals.   

Thus today, for the dairyman (or cattleman) who wishes to consistently produce functional and adaptable replacement stock, “aAa” defines “type” in a way relevant to daily herd management.  
The six broad physical qualities defined by “aAa” have impacts on all levels of function:
(1)   Production,   (2)  Reproduction,   (3)  Health maintenance,   (4)  Adaptation to the physical environment,   (5)   Efficient use of feed,   (6)   Vigor, mobility, trainability.

You can manage the heritability of physical structure

You may already have observed “frail” cows, leading to early age death or culling from the production herd.   If you track calf ID to their dams, you may wonder how successful cows can produce “frail” daughters, and it is as logical to blame that failure on her sire as it is to lay it at the door of feeding, vaccinating, housing and the stress of higher production.    You may not have realized that “good” genetics can produce such “frail” animals, as a result of any mating that did not recognize the advantages in “balancing” the qualities between cows and their mates.  
However, if you ask any user of “aAa” if frail cows are caused by mating decisions based on the  popular theories of “likes to likes” breeding (milk on milk) (selection index), they will tell you Yes—after using “aAa”, the “frail” heifers no longer show up in their herds.

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