Both AI stud mating evaluators and Holstein USA type
classifiers use the linear trait methodology to categorize the functional
structure of the modern cow. Often
times, they do not agree on what that “perfect” cow should be physically, with
the AI stud view (joined by Genomic scientists) being that our modern Holstein
cow is “too tall” for commercial environments, while the Holstein classifier
and farmer breeder view is that they see too many fine-boned, deep-uddered
young cows they would not expect to live a full productive lifetime.
Scientists, who first developed the linear type
methodology in the 1970s and joined with AI studs to coerce the purebred breed
associations to adopt it for official breed type classification, now tend to
blame type classifiers for the cow faults in execution of the linear
concept. Meanwhile, breeders are
sticking with the idea that the higher scored “Very Good” and “Excellent” cows
will be the longer life producers, and object to the Genomic assumption that
“Good Plus” is the best type for commercial use.
Then there is the “aAa” view
The Weeks’
“aAa” Breeding Guide is used in both commercial and purebred settings, but has
never been officially endorsed by either side of the argument—thus tends to
function “under the radar” to help its users avoid being trapped in the fads
and fancies from theoretical science and traditional breeders that periodically
disrupt functional cow structure in popularly mated herds (using computer
mating systems or personal AI consultant mating).
In the Weeks method, the qualities of
the cow physique are assembled in an additive way, rather than in a preference
for linear extremes in a handful of target traits. Over my now twenty years as an approved
“aAa”
analyzer I would say that our
current type issue is the prevalence for “narrow” physiques,
which comes in part from the linear evaluation (by AI stud or breed classifer)
preference for “angular” cows.
How a lack of “width” translates into a lack of “functional cow”
You can start right with the fore part of the cow, that
linear concepts of the 1970s decided had no value:
the
head. 100% of the air she breathes, the water
she drinks, and the feed she eats has to enter the cow through the dimensions
of her head. If the head has a wide
muzzle, big round nostrils, and a wide sinus structure, she has a chance of
high performance. If she has a wide
forehead, there is room for the eyes to swivel in the skull and the brain to
work inside the skull. If the head is
proportionate in size to the body behind it, you will find that all the body
parts have more substance and function cohesively.
By contrast, too many linearly-selected heifers today have narrow heads,
small muzzles, weak jaws, slits for nostrils, and spend too much time panting
around the water tank any time heat or humidity rises. In any stress situation, the narrow skull
squeezes the brain and limits the range of her eyesight, producing a nervous
cow. Cows with narrow heads have less
inherent balance when on the move.
Correlations between narrow heads and narrow chests, slabby ribs, stiff legged stances
Stand in front of any narrow headed heifer. Do you see any front end capacity behind
that? Keep in mind that the heart sits in the center of the chest with the lungs aligned on
either side. The lifeblood in the cow
is circulated out to muscles by the heart, and the oxygenating of the returned
blood is performed by the lungs. Both
need chest room to fully function, the extension and contraction of both
takes room.
Why narrow cows have more D/As early lactation and lose persistency late lactation
The first issue with a narrow body
will be the narrow front leg stance and foot shape. Without width or depth in the chest, the
fore legs will be positioned close to each other. This produces “imbalance” in the cow’s
front end, whether standing or walking.
A “sturdy” cow will have legs far enough apart to stand “square” in
front, with her feet pointing straight ahead and the distribution of weight to
hooves will be even “side to side”. A
“narrow” cow will spindle her foreleg, stand with feet toeing out, and you will
see the front toes wear unevenly, representing the unequal distribution of
weight at the toes.
The next issue with a narrow body is
the slabby (vertically flat) rib shape, which starts from a narrow (more
vertical than horizontal) chine structure behind the shoulder. As the rumen fills inside the body, it will
quickly come in contact with the slabby rib, and this will constrict
appetite. Production genes selected
on high early-lactation peaks in the 1970s genetic preferences used a faster
metabolism as the means to increase production from higher levels of grain
concentrates, because the narrow body was a restriction to efficient use of
bulky, high forage content rations.
Such cows, however, lose more body condition as a result of persistent
negative energy states, and this leads to more ketosis and displaced abomasums.
Having more “spring” and “openness” of
rib (two different qualities, which linear confuses into one) creates an
expansive body cavity that allows the rumen full room to “stretch and roll” and
thus such a cow will have a more consistent appetite, less likely to fall into
an unhealthy negative energy state.
Where is the abomasum?
The “abomasum” (fourth stomach, final
nutrient absorption) sits underneath the rear of the rumen, thus in the flank
and rear rib region of the cow. For a
cow to be persistent in yield in later lactation, she is going to need
both “depth” of rear rib and depth and spread of the “flank”
region—because the fetus is developing into a calf in the same interior space
of the cow. If the calf is competing
for room with the abomasum, the calf will usually win—at the expense of the
yield of milk.
While today the leading edge of
Genomics is studying “feed efficiency”, the role of the rumen in feed digestion
(and the cow physique that can optimize rumen function) has been overlooked by
geneticists who focused only on milk volume (preferring bigger, taller cows),
rather than on the efficiency of milk synthesis on a given volume of feed
(preferring smaller, wider cows with traditional “dairy” character).
Wide rear ends—house the udder better, birth the calf easier
Any time you sense the hind leg is too close to the rear
udder, you are milking a “narrow” rear end cow. This increases risk of leg or hoof injury
to the udder or teats, and risks hiplock during any calving. As the udder matures, without proper pelvic
dimensions, the udder can only grow “deeper” and thus even the life and health
of the udder (seemingly unrelated to body in linear trait theory) is
jeopardized.
Think
about it. How many of your cows are you losing as a
result of problems that can be linked to a lack of functional “width” in the
heifers you are breeding? If in
doubt of a solution, consider this:
The
best fix to the solution you are seeking will be the concepts that explain the
cause of the problem.
You just read an “aAa” method explanation of why so many cows die too
young. Maybe using “aAa” instead of
reductionist linear trait thinking could solve some problems that are costing
you money.
No comments:
Post a Comment