By Gearld Fry
According to the EPD
world and modern day bovine research, reproductive performance has a very low
inheritance rate; therefore there is no reason for cattle producers to select for
something they have been told that they have no control over. Right? I totally disagree.
Selecting for reproductive traits is no more
difficult than breeding the horns out of a herd by using a polled bull
for consecutive seasons. Horns could be bred back into a herd as well if that was a goal. Many reproductive traits are as visible as horns. When one learns how to select seed stock that exhibits these traits, the gene pool will be
further concentrated with each succeeding generation and the hereditability of
such desired traits will greatly increase.
In discussions about heredity, it is a matter of dominant and recessive genes that
govern the expression of the trait. For instance, if a homozygous polled bull is bred to horned cows, all of the calves would have a dominant polled gene from the sire and a recessive horned gene from the dam, yet they would all appear as being polled. But if instead the polled bull was heterozygous, then half of his offspring would be horned and half
polled. If all horned animals were eliminated from
the breeding herd, it would only be a matter of two more generations
(assuming a homozygous polled bull was used again) to completely eliminate horns
from the herd.
Animal Selection
The anatomy and physiology of an animal is
directed by the genetic material it receives from its parents, so why
would reproductive traits be any less inheritable then others? They are not. What has happened is that the schools and universities that are
supposed to be teaching and guiding us have been too focused on rate of gain on grain. Because they have not had the true burden of making a living and supporting a family with a
livestock business as the sole income, they have not had to purposely concentrate
and learn how to select animals that will pass on desirable reproductive
traits. I feel certain that some quality
animals (animals with the correct reproductive traits) have come and
gone through university programs. But
because they weren’t paired with like quality animals, and also because
the practice of crossbreeding has diluted the gene pools, the resulting
offspring didn’t possess the reproductive traits expected. Therefore it was decided that such traits had a low inheritance rate.
Another misconception that has infiltrated cattle production is the notion that
“good” cows are what count. The bull has been reduced to merely the
impregnator. Cows will always get the credit for producing
nice calves. How can one evaluate reproductive traits in the cow and leave the bull completely out of the equation? You can’t. Last time I checked, the bull was
responsible for half of his offspring’s genetic make-up. You cannot increase or
improve reproduction in cows without the use of a very fertile bull.
Most seed stock producers, including those that line breed, look to the cow
for all reproductive performance traits. They give her full responsibility for the quality of her daughters and sons. Breeders use a bull because he is out of a
particular cow or cow line that they like. In many cases these cows are the matriarch of the farm. So often there is no regard for a sire’s
ruggedness, masculinity, testicle size and shape, or quality of semen at puberty. A bull (son) from one of these QUEENS OF
SHEBA mothers possesses more maternal characteristics than paternal.
Bull Selection
The result of using this type of bull selection for breeding is that one
will have a pasture full of decent females, but the bulls will be frail, fragile,
and far from masculine. Most breeders shy away from using a real masculine bull for misunderstood reasons like they will cause
calving difficulties.
America’s
cattle herds are made up of female-dominated gene pools. These gene pools effectively create daughters that are clones of their mothers. Unfortunately the male calves are clones of their frail, fragile fathers. This type of breeding may be
alright for the feedlot-grain industry, but it will not work for grass
fed cattle.
Cattle Breeding Rules
The basic ground rules of any
cattle breeding operation start with having cows that drop a live,
healthy calf every year on time. Females have the
innate ability to recreate themselves in their daughters through a
genetic process know as cytoplasmic inheritance. This process has the dynamic ability to override and in effect mask inferior traits passed on by the sire. I
call it an act of God’s grace that saves us from our continued breeding
follies, but it is a double edged sword that has caused the epidemic of
inferior bulls. Cytoplasmic inheritance
is terrific when all of the mother cows already possess all the desired
traits necessary for high performance on grass. Does that describe your herd?
My point is that in order to make improvements (growth, carcass, grass utilization, reproduction) in your females or males, it requires using a very fertile, masculine bull. It is widely taught that crossbreeding and outcrossing will improve reproduction in the cow. Don’t be fooled by the higher reproduction
and growth performance that occurs in the first year’s offspring. The generations following will be even more mongrelized and you will loose control of the traits you were selecting for in the first place. Your holy grail will
crumble.
Reproductive traits are as visible
as horns and they start to become obvious within months after birth. The stifle muscle becomes more pronounced with the onset of estrogen production.
Early maturing female calves will show this by 3-4 months. Late maturing females do not have this stifle muscle development before 4 months. Early maturing females should be actively cycling by 5-7 months of age which triggers udder development.
A yearling heifer that has developed a nice little maiden udder with four well formed nipples pointing towards the ground is a visual indicator of her reproductive abilities.
We know for reproductive performance a yearling heifer’s rump is to be 2.5 inches wider than it is long. A reproductively sound female will naturally
carry a ¼ inch of back fat by 12 months of age.
This is her energy reserve that will foster her ability to start
cycling again soon after calving.
A side note about females that naturally carry a layer of back fat:
Most often these types of cows need to stay working. In other words they need have that nursing calf at their side until it reaches about 10 months of age in order to
maintain a condition conducive for easy conception.
When we wean the calf from this type of female at the 205 day
period, she may become fat and difficult to get pregnant. All
too often these cows get sent to market because they are jaded as unbreedable when in reality it was ignorance and mismanagement that was the problem.
Another accurate method for selecting for reproductive performance is to physically palpate the uterine bodies and ovaries of yearling females. This will show exactly where they are in their reproductive tract development.
Early Maturing Animals
It is critical to have early maturing animals for high reproductive performance and efficiency. If a yearling female’s internal reproductive
tract is small and her udder (external) is also small, she is still in
a juvenile stage and will mature late. If her ovaries are developed enough to cycle yet her uterus is still small, she is still late maturing. Either way
longevity is not in her favor.
A young heifer should reach full puberty by 12 months of age, but I do
not recommend breeding any heifer before she is 20 months old and I believe
24 months is even better. Although she is receptive and able to conceive, a female is not mature physically before 24 months. To limit the amount of nutrition
available for a heifer’s growth in exchange for a developing fetus will
only compromise her longevity. Pregnancy at this stage will retard her physical development and maybe even stunt her for life.
The cows that do get pregnant, maintain that pregnancy, raise a healthy calf, and breed back easily year after year are the ones that have been allowed to mature before their first
conception. The wild animal kingdom is proof of this. These early cycling, early
maturing females will pass their reproductive traits onto their daughters and
when managed properly will sustain your grass-based operation.
So where does the bull fit into this reproduction performance equation? He is
half of the genetic make-up of all his offspring. You may say, “Well of course”, but yet so many breeders put their emphasis on the cows and fail to realize the
harm they’re doing by using a mediocre or even worse - inferior bull on
those cows.
I repeat: Selecting for optimum reproductive traits is no different then selecting for polled or horns. The testicles are the factory for the male
genetic material that is to be passed on. A small or defective factory produces a limited amount and/or defective sperm. There are several levels of semen
quality. What kind of factory is responsible for producing your next calf crop?
To assess the ability of the factory is to evaluate the confirmation of the testicles as well as the sperm that comes from them. Testicle size and
shape, placement of the epidydimis, testicle texture, scrotal skin and
crease, scrotal neck, and amount of primary and secondary abnormal sperm are
all physical features that indicate level of reproductive performance.
Early maturing, amount of muscle development
(masculinity), and libido (sexual prowess) are visual indicators of a
bull’s reproductive traits. Any defects in these various traits will be passed on to the sons and daughters. The goal is to select against any defects.
A bull will have the genetic
ability to reach a certain quality and level of semen production.
If that genetic level is high because his
parents were selected and bred for that level, then he too will pass
those desired reproductive traits on his progeny, both sons and daughters.
If he is a bull that has a 60-75% live semen
count (forward moving) and any higher than 8-10% abnormalities, he is
low in reproductive performance traits and will not improve reproductive
traits in his offspring. Just like other inherited
traits, reproductive traits are part of the genetic material located on
the DNA in the nucleus of the sperm and egg. The
Rotokawa bloodline Red Devon Bulls that the Bakewell Reproductive Center
promote test above 80% live semen with less than 5% abnormalities
(primary and secondary).
Dr. Richard Sacky found that when a group of bulls were put in the same pasture with a herd of cows that 75% of the calves were sired by just one bull. Many
if not all of the other bulls had inseminated the cows, but it was the
bull that possessed the highest level of masculinity and libido, the bull
with the highest level of testosterone and thus semen quality that had actually
fathered the calves. In his research he also discovered
that the ovum had the ability to select which sperm cell could
penetrate its outer membrane and enter for conception.
In his studies the cows’ ova were selecting the strong semen
from the virile bulls for fertilization.
In order to make genetic progress involving the reproductive traits, the sire must posses a high level of masculinity and the dam must posses a high level of femininity, both by
12 months of age. Only then will you begin to produce uniform offspring with predictable results. I have mentioned several physical, visual, palpable characteristics in both the bull and cow that indicate level of reproductive performance. To select for
these traits and leave the bull out of the equation leaves the entire
burden upon the female. God did not create either sex to work alone, not when it comes to creating and strengthening the next generation.
You will not put reproductive
performance back into your herd without using a bull that exhibits all
the required reproductive traits discussed. Without a very fertile, virile bull the inheritability rate of reproductive traits stays low just like the industry research and EPDs
lead us to believe.
Remember you cannot put horns on a bovine without using a horned sire and you cannot remove horns without using a polled sire. The next time you hear how
reproductive traits have a low inheritance rate, tell them you know different. Pay attention to the bulls you use. Start with anything less, you end up with less.
|
