The late
Allan Nation as editor of Stockman Grass Farmer once did an
article with some simple math comparing the Western range cattleman (grass-based
farmers) to a Midwest feedlot (grain-based farmers) and where their basic
attitudes came from, as they affected breeding and feeding selection.
The western range cattleman focused on grass production and overwintering with
hay felt his ranch income depended on the fertility of his cattle
(and, more recently, his soil). Their
goal was a 100% live calf crop, first. They preferred a cow who could milk enough
to wean a calf half or more her body weight, on primarily grass, second. In summary, they bred for fertile,
easy-calving, maternal instinct cows who would milk on grass long enough to
wean their calf.
Allan did the math this way: 100 cows
bred, weighing 1100 pounds, producing 100 live calves, weaning off 550 pounds
of calf per cow, yielded 55,000 pounds of salable feeders.
By contrast,
the midwestern grain farmer with corral cattle, by necessity being fed
harvested feed year around, heavily invested in barns and machinery, impatient
with fencing and pasture management, was only satisfied with a 700 pound
weanling so tended to have 1400 lb. cows and did a lot of creep feeding to
supplement momma’s milk supply. Data
on typical feedlot farms showed generally 10% of cows failed to conceive and 5%
of the cows failed to birth live calves.
150 pounds of calf growth came from the creep feeding rather than
momma’s milk. You had an extra 300
pounds of cow to maintain all year long, pregnant or open, wet or dry.
Allan did the math this way: 100 cows
exposed, weighing 1400 pounds, produced just 85 live calves, weaning off 700
pounds, a total yield of 59,500 pounds of salable feeders (but at higher
cost due to added cow size, the creep feed offered calves, and the added
facility investment).
Which
model is at fault? With so many midwestern
land-grant universities and all their fellow associated feed, chemical, seed
and machinery vendors all recommending seek the highest yield at the
required higher input costs to insure the yield, it is no surprise that so
many cattlemen are disdainful of the grass-based, low-input cow-calf
system. Certainly the focus on EPDs
and DNA indexes in major breeds like Angus and Simmental to determine the
“best” sires to use reinforce the mantra to maximize yields.
However, as in all commodity production systems, the highest margins of profit
come from the most cost-effective optimization of inputs. Profits in commodity production come
not from the highest yields, but from the lowest costs of production per yield. In the case of animal genetics, this
means cow fertility, cow longevity and live calf births are the
highest profit traits.
How do we identify better genetic sources for these primary breeding
traits? This is where we see a wide
disparity in how cattlemen approach the choice of herd sire(s) both for AI use
and for natural service in rangeland or AI “clean up”.
INDEXING
Do EPDs
help identify the most fertile, maternal, longevity-capable cows? Definitions of the
summary traits predictably used in advertising:
EPD = “Expected Progeny Difference”
compares the bull to contemporary and historical sires.
CE = “calving ease”, the percent of unassisted births by comparison to other
sires.
BW = “birth weight”, in pounds, progeny compared to other sires.
WW = “weaning weight”, standardized at 205 days of age, in pounds, compared to
other sires.
YW = “yearling weight”, standardized to 365 days of age, in pounds, compared to
other sires.
Mk = the number of herds reporting
progeny data on this sire to his breed association.
Marb = “marbling score”, this is a
combination of live visual estimation and carcass measure.
RE = “ribeye area” (square inches), of course, this is where the highest value
meat cuts are.
$B = “Beef dollar value”, terminal
composite score, est. carcass value as graded at slaughter.
$C = “Composite dollar value”, combines
breeding replacement value and beef dollar value.
In other words, open cows, dead calves, services per pregnancy and calving intervals are not being compared for sires (although the data would be accessible from herd records). EPDs are focused on income generation, NOT on cost control.
LINEBREEDING (Inbreeding)
Does linebreeding aid us in producing more fertile, maternal,
longevity-capable cows?
Linebreeding was integral to localized and regional breed formation, as
prior to automobiles it was not practical for bulls to be shipped in numbers
from one continent or country to another.
England and Scotland alone produced a dozen distinct meat breeds as well as the
more refined frame dairy breeds, generally named for their region of origin
(ex, Devon, Galloway, Highlander, Aberdeen Angus, Durham, Hereford). A bull used a couple seasons could in turn
produce sons who got mated to their paternal half-sisters. The best then would produce the next
generation where “cousins” were interbred.
Desired genetic qualities in the foundation bulls and cows get
reinforced over multiple generations of close breeding.
The most remarkable example of this process is the USDA “Line One” Hereford
program in the western USA where a “closed breeding herd” has been maintained
over 80 generations.
Therefore, if the original breeding animals possessed good fertility, maternal
instinct, and will to live, these characteristics will generally be maintained
or even reinforced by linebreeding.
CROSSBREEDING
Just how beneficial is the heterosis (“hybrid vigor”) response from
crossbreeding?
At the terminal cross, it is generally acknowledged, for example, that a
“black baldy” (Hereford x Angus cross) will outgrow (out yield) purebred Angus
or Hereford calves from the same sires.
A crossbred steer is like hybrid seed corn, and the “triple cross” seems
to be the peak of response.
Crossbreeding to produce cows, however, has diminishing returns. You need a “base” breed to maintain
maternal efficiency and fertility in your cow herd, otherwise randomness takes
over.
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