Beef producers are often called upon to buy feed,
minerals, equipment and other items promised as the “best investment
for your farm.” The only one real investment in the farm that can
always live up to the promise is the bull in the pasture. If you have a
closed herd, the genes in that cow herd will come solely from the bulls you
select after just a few generations.
For the beef cow-calf enterprise, the sale of a live
calf is the only source of income—unless you count the sale of cull
cows that did not get bred or lost a calf. The first step is having a bull
available that will accomplish two things: get the cow bred when she is in
heat, and provide the most pounds possible across the scales at sale time
for the calf.
Getting the cow bred
If we track the cycle of events that leads to a live
calf across the scales, we have to have a fertile bull with a fertile cow
at the right time. Fertility in young bulls is a function of age, genetics,
nutrition and other factors. The only objective method of measuring
fertility is with a breeding soundness exam (BSE), which combines most of
the factors involved in fertility (scrotal size, sperm concentration, sperm
morphology and a physical exam of the reproductive organs) to arrive at a
score that will value potential fertility. Failure to meet specific
benchmarks for any of the factors results in a BSE failure. This score has
been proven in the field to be very efficient in measuring bull fertility.
Most central bull tests stations provide a BSE exam on bulls sold through
the program. There are few veterinarians available, however, that provide
an on-farm BSE.
A second factor of fertility in bulls is making sure
the fertile mating can occur. Yearling bulls that are turned in with more
than 15 to 20 cows will result in a costly breeding season. A yearling
should not be expected to breed more than one cow per day. If we consider
there will be at least one cow in heat every day in a 20-cow herd (a 21-day
reproductive cycle), this is the maximum breeding herd for the young bull.
It can be increased to 30 cows for the 2-year old, but should never exceed
40 cows for any bull, because a cow that has a fertile heat, but is not
bred until the next heat cycle, will cost the producer about $40 per calf
from lost weaning weight.
A third factor is buying the bull that has a greater
chance of producing a live calf. Birth weight of calves is the single most
important factor in calving difficulty, and difficult calvings result in
dead calves, dead cows and/or cows that do not rebreed. Using genetic
information such as EPDs (expected progeny differences) for birth weight
have proven there will be fewer difficult calvings and more live calves.
All breed associations publish the average EPD for birth weight in their
population of bulls, so select bulls that are below breed average for birth
weight EPD for breeding young cows. Keep them below breed average if
heifers are to be retained in the herd from any cows because half of the
genes for birth weight come from the dam.
Getting more pounds
The most expensive bull a producer can buy is the
one from the sale barn with no genetic records. It is like buying a tractor
to pull a six-row corn planter without looking at it or knowing the
horsepower. The technology for breeding cattle is such that there is no
reason to buy inferior bulls. EPDs, performance records and genetic markers
are all there to use to get the most from the bull-buying decision.
Consider this example of using EPDs to select two bulls:
|Birth weight EPD
|Weaning weight EPD
These EPDs tell us that, when bred to an average
group cows, Bull A will wean calves that are 15 pounds heavier than Bull B,
and both will have the same average birth weight. If we use these bulls on
an average of 30 cows over four years, and wean 90 percent of the calves,
we will expect Bull A to wean 1,620 more pounds of calf. At $1 per pound,
that is $1,620 more value over the life of the bull, which is why the
$1,500 bull is about $1,100 more expensive to own than the $2,000 bull. We
actually did this comparison on a farm a few years ago, and found the
difference was more like 50 pounds per calf, and a bull that could be
bought for $2,000 was actually worth $5,000 to that herd. Consider, also,
that bulls are “rented.” For the initial cost of $2,000 for a
bull that is sold for $600 when he is culled after just four years, the
cost to breed each cow for 30 cows each year is just $11.66.
Impact of Bull Selection in a Closed Herd of Beef Cows
||Percent of genes from selected bulls
|20 percent replacement rate in the cow herd
In the decision to buy bulls, set the goals for the
herd, find bulls with the genetic information that can reach those goals
and disregard bulls without known genetic value. Then, select bulls based
on the breed, phenotype or color you want. It will be the most important
investment you make.
Dr. John Comerford is associate professor of dairy
and animal science at the Pennsylvania State University.