(December 2009) by Greg Palen Netherhall (polled, grazing)
Jerseys
Why Raise any Bull?
Artificial Insemination was first
organized in the USA during the 1940s, to accomplish several goals of dairy
cattlemen: (a) Make dairying safer (bulls can be dangerous, both to people
and cows); (b) Eradicate venereal diseases (bulls can
spread trouble, like brucellosis, vibriosis, and trichinosis, all causing
infectious abortion); (c) Improved herd management (have more exact dates for breeding, thus
dry off and due dates); (d) Put a
productive cow in the bull’s space (incremental income gain, lower net
reproductive expenses); (e) Provide genetic variety (avoid having
all your “eggs” in one “basket” of unknown genetic value).
After six decades of commercial AI
activity, however, many dairy farms continue to use herd bulls, or have
reverted to their use after trying AI and not always succeeding. Problems that lead to natural service
reproduction include: (a) No one on the dairy has good insemination
skills, (b) Commercial AI service is not available in
that area, (c) Personnel lack the skill for effective heat
detection, (d) Facility design does not acccomodate AI
easily, (e) Preferred breed of cattle is not available
within any AI system, (f) Selection traits of interest to herdowner are
not considered important by those in AI who are selecting which bulls enter AI
service, (g) Dairy suffers under a skilled labor
shortage, (h) Herdowner has a passion for genetic selection
and wishes to develop his own bloodline(s).
While many of these problems can
be solved, not all herdowners wish to invest the time and money, or have
elected to defer the introduction of AI to a later time, after more immediate
needs are met. It is also not uncommon
for many dairies to use AI in tandem with natural service, for example:
Seasonal calving windows under grazing management
In this scenario, where animals live in paddocks (rather
than barns) and calving is not desired all year long, progressive graziers will
focus AI on two to three cow cycles, first introducing the service bull to the
virgin heifers, and then moving him with the cows to “clean up” any still open
after 4-6 weeks’ AI.
This program focuses heat
detection on cows being milked twice daily and thus closely observed, and gets
heifers (under less observation) to calve in the same season as the cows.
High group – Low group feeding in confinement
In this scenario, the AI activity is focused on the
fresher cows, who are grouped in the same pens and thus are all “open”, most
are cycling, and will be more likely to exhibit detectable heats (known as the
“dormitory effect”) from a consequence of “gang” cycling activity.
Pregnant cows are moved from the
“fresh” group to a “bred” [low, ie, not as fresh] group, thus hardly any
cycling activity is going to be detected.
Putting a bull in such a group insures “someone” is still doing heat
detection, to catch cows that reabsorb, or who are moved there after repeated
AI attempts.
Gang bull breeding
Some very large herds will insert multiple bulls into
large cow groups to stimulate earlier repro.
Why not buy such bulls from a higher-profile
breeder?
In most cases, this is what we do,
and it comprises a steady source of added income to the purebred breeders in
dairy communities. As these are guys
investing a lot of time and money into the type classification and official
milk testing of their cows, maintaining accurate ancestral identity, perhaps
utilizing some added repro technology (embryo transfer, cloning, genomic
testing, etc) and focusing their semen purchases on the “elite” ranked sires of
their breed, we just assume their cattle have more transmitting ability
(capability of genetic improvement) than our own. After all, these are the herds producing
bulls for the various AI systems, who promote higher “genetic value” sires.
The dairyman not utilizing AI but
who believes the AI sires are clearly superior, is highly likely to do just
that—in fact many ET full brothers to AI sires end up as “jumper” bulls in
dairy herds. This is a natural economic
consequence of the propogative technologies (super ovulation and embryo
transfer) as well as the further level of screening AI systems now do from the
availability of Genomic testing (DNA mapping) which is reducing the number of
“full brothers” being sampled by AI studs.
While more pedigree (sire x dam) combinations are resulting from Genomic
screening, this also means more surplus sires are being propogated. [Studs expecting to sample 240 young sires
annually are writing 1200 sire contracts, but only taking one out of five bull
calves produced, based upon which one has the highest Genomic estimates of
“genetic value”.]
The addition of Genomic testing to
the sorting of ET sires may imply the bulls left for natural service do not
possess the desired DNA markers. This
should give us pause—do we wish to use a “reject”?
Reasons you may prefer to raise your own herd sire
First, there is the herd health issue. You do not have a “closed” herd (closed to
any possible disease exposure that could come from new animal contact) if you
keep bringing in bulls from other farms, in which the health status and disease
exposure is different from yours.
Raising your own herd sires is a way to more fully reach a “closed” herd
health status.
Next, there is the issue of “selection trait focus”. You may not agree with the trait selection
priorities of those breeders accessible to you and raising jumper bulls. This is an issue that is growing bigger
each year. For example:
Organic dairy production. Certified organic producers need “healthy”
(disease resistant) and self- reliant cattle. Some of the higher genetic value animals,
bred to more extreme performance levels, demand a higher level of feed
supplementation and daily labor care to maintain their productivity, or in more
cases, their reproductivity. In an
organic production model, where antibiotics and hormone therapies are not
allowed, such genetics may result in higher than desirable cull rates.
Polled heads. Dehorning as a dairy farm practice is
already an “animal rights” issue in Europe, thus an increasing veterinary
expense for EEC producers. Likewise,
in subtropical dairy areas, where no winter occurs to break parasite cycles,
polled heads avoid a lot of wound infections and growth rate setbacks. Graziers calving outside in tight seasonal
windows, raising spring calves in paddocks, find the dehorning job to be
onerous, and occurring in the “fly season”.
Thus, demand for polled cattle increases, while the supply of polled AI
sires grows very slowly (and is mostly heterozygous polled, ie, still producing
50% horned calves in horned herds).
Specialty milk production. One of the developing market niches is for
“A2A2 Beta Casein” milk, a genetically-determined milk quality claimed to have
health benefits to those recovering from cancer.
Likewise, a dairyman who has entered on-farm artisan
cheese production for retail marketing of his milk, may wish to select for “BB
Kappa Casein” milk, a genetically-determined milk quality that will raise
cheese yields 10% to 15% over conventional blend milk at the same levels of bf%
and pr%.
Why
are premium gene traits for milk composition mostly ignored by AI?
While most AI systems test for Beta Casein and Kappa
Casein genotypes as part of the screening tests for Genomic evaluation, the
data is neither routinely published nor does it have much impact on which sires
are chosen to enter AI service.
Likewise, sires rarely get the nod for AI due to being polled, as long
as some other bull has a higher ranking on some screening index. Commercial AI selection is driven on
“ranking indexes” rather than trait selection matrixes, virtually worldwide.
The justification for ignoring unique selection traits is
mostly driven by the commodity focus of milk cooperative marketing, where milk
from different (and unique) farms is “pooled” – first by the milk haulers, next
in the silos of the receiving plant--
any market demand for a specialty milk composition is only provided if
it can be accomplished at the balancing plant by separation and
reconstitution. As local AI systems
merged into regional and national entities, their interest in providing all
sires for all local tastes (breeds) (bloodlines) (trait mixes) has declined,
looking only at broad market statistics to make decisions as to future sire
selection preferences.
Most purebred breeders raising bulls are thinking about the AI market, not you
Purebred breeders using OvSynch, superovulation and
embryo transfer, Genomic testing their cows, are focused on the AI sire
paradigm. They wish to recover those
costs from premium bull sales to AI studs and premium embryo sales to other
breeders wishing to enter this “index” driven market.
Thus, buying a bull from them to breed your cows is like
using year from certified bank-run seed to plant a wheat crop. You did not get the “best” genetics but you
got a close approximation of those genetics.
Thus the question is as follows:
Do I want to breed cows just like the commercial AI cows for my
herd? If so, save time and buy
your purebred neighbor’s left over ET bulls.
If, on the other hand, you have more specific selection
goals, or a more unique focus in milk quality production, and your management
environment and/or milk marketing differs from the commercial, commodity
definition, you either have to raise your own herd sire or
seek breeders who already are focused on producing the sort of
genetic mix you wish to gain.
In saying this, I am firmly identifying myself as a dairy
industry contrarian, in that I do not have a blanket belief that AI sires are
automatically superior to what you could raise. I remain a firm believer in AI as a useful tool
that can help you become a better stockman, as well as a more profitable
businessman. When all the costs are
accounted, basic AI technology saves you money over average natural
service results. We sometimes
just have trouble recognizing what those costs are.
The large number of custom semen collection businesses
(and not just in areas driven by beef breed cattle breeders) suggests that many
today are utilizing AI, but from their “own” stable of sires.
You really have to have sound reasons for raising your
own herd sires, to bear the added costs.
In some cases, specific (unique) genetic goals justify the added
costs. In other cases, the opportunity
to develop a niche market for bulls from your farm can justify the added
costs. In either case, you may still
find that you still wish to have access to AI technology as well as sires you
can source via AI, to get all of your genetic “bases” covered.
Where
do I start to produce a useful herd sire?
Dairymen milk cows. 98% of all dairymen produce an income
stream based entirely on what cows produce (milk, replacement heifers,
deacon bull calves, and cull salvage).
Only 2% of all dairymen generate meaningful farm income from breeding
bulls, and only a fraction of that 2% are able to sell bulls into AI systems on
a regular basis.
A useful herd sire thus has to be produced from the
perspective of what is a useful cow.
(This should be the first point at which you start to question the
current market fixation over “sire index” rankings.)
What do you mean by a “useful” cow? Simply put, a cow is “useful” if she can
successfully do all the functions you ask of her each season. Can she calve a live calf? Does she get up and get going
as a milk producing cow after calving?
Will she rebreed at the time your calendar prefers? Does she avoid added costs that
reduce the profitability of her production (vet assisted births, milk fever,
metritis, ketosis, displacements, hoof trimming, chronic lameness, mastitis,
induced repro after failure of natural heat insemination, long dry periods,
fatty liver post-calving)? Are her
calves vigorous or prone to pneumonia, scours, finicky eating habits,
poor at making transitions? Does she
have the type to enhance your herd equity and make daily milking
easier? Does she have the physique
and behavior to adapt to seasonal or structural or nutritional changes
in her environment?
It should be evident from such a list, that our
traditional measures of cows—DHIA milk test records and Breed Society type
scoring—only scratch the surface of answering the “useful” question. But a good on-farm record keeping system
designed to observe and record “usefulness” will make a sound basis for the
selection of cows who can produce “useful” herd sires.
Analyze your “useful” cows from a “lifetime
performance” basis
The dairyman just starting out can have difficulty
determining whom his most “useful” cows are, as it takes more than a single
lactation to answer all those questions posed above. It is for this reason that many traditional
stock breeders preferred the oldest successful cows to be “bull mothers”. This flies in the face of the “newest
generation is best” fast turnover of pedigrees in commercial AI selection, a
market that routinely buys bull calves from first lactation cows. But bear with me on this.
Each year is different.
Different weather produces differences in forage qualities and
quantities, can impact on daily comfort of cows, can affect the prices we are
receiving for milk and produce years in which we tighten our belts and reduce
input uses to those we can produce internally. If you judge a cow on a single year of
performance, you will overlook factors of adaptability—was it a good year
to be a cow at your place, or a tough year? Basically, analyzing cows over an
accumulating lifetime of performance is a better guide to
answering all the questions posed regarding usefulness, even if you are
not convinced of the economic advantage many of us assume for cows with longevity.
If you find you are only saving bulls in years where
performance came easily, you will not be putting enough selection pressure on adaptive
and longevity characteristics.
Such bulls will produce milky heifers but may not possess the
genetic qualities to make them equally useful in difficult years. This is ultimately why we sometimes see most
of our mature cows culling out in a single year—we did not produce them from
selections (and matings) that took longevity and adaptability into
full account, and they could not survive all the challenges thrown at them in
that year. Lesson one: Save bull calves from “survivors” – not
just from pretty heifers.
Cow families develop around more useful cows.
For the dairyman who has had his herd awhile, has thought
about breeding quality and done some trait selection, a symptom of success will
be the existence of cow families in the herd. A “cow family” is an extended line of
maternal relationships. It can be a
multiple generation of cows descending from a single older cow; it can be a
group of cows all descendent from maternal siblings. The point that we need to see is this—a
cow who has successful fertility genes and normal herdife survival will produce
more heifers in her lifetime than a cow of mediocre fertility and average
herdlife. These heifers in turn, if
bred to the same or higher level of ability, will also produce more heifers. “Cow families” accumulate in soundly
managed dairy herds as a result of superior genetic fertility and longevity. In the experience of those breeders who were
concerned about this, it is consistent that these “maternal” traits would
follow cow lines directly, and thus sire lines indirectly (as cow fertility
genes are easier to verify from the maternal side of pedigrees).
Bull fertility is pretty simple compared to cow
fertility. All the bull has to
do is develop a healthy set of testicles, not be overconditioned when young to
avoid fatty tissue in the testes, learn to jump-mount and have enough libido to
either serve cows or collect semen. In
the case of AI, his ejaculate must have the volume of sperm cells, and those
sperm cells must have the vigor to survive the freezing and thawing process
under conventional (1/2 cc straw) packaging.
These are the relatively simple factors of bull fertility. AI studs feed high energy rations to bulls
on full collection schedules so as to keep a stable level of body condition as
a support to their libido, and restrict their collection to a two or three day
per week schedule determined by the volume of sperm production.
Cow fertility is more complex. Cows, on the other hand, have to
fit their reproduction around cycles of ovarian activity that are driven by
hormones produced in various glands.
Cows do not “produce” eggs like bulls produce sperm cells—they are born
with a lifetime supply in their ovaries, and instead their cycles are designed
to mature and then release an egg according to their body schedules. All of this has to occur around the
physiologic demands of milk production and the post-calving recovery of the
uterus. Periodic calving alters and
ultimately ages the cow’s body in ways that sperm production never could for
any bull. This is true for all
mammals, as the fetus is incubated within the body of the mother of the
species. (The father is just a passive
spectator by comparison).
Natural service bull fertility is different in execution
from AI service fertility. Over
decades of the advancing technology for semen collection and sperm
preservation, we have advanced from chilled, liquid semen (good for a few days)
to frozen semen (storable indefinitely)—we have advanced in the freezing
knowledge from fat ampules (that killed a majority of sperm cells) to thin
straws (that save a slim majority of sperm cells), with two consequences: (1) Straw
technology enhanced the conception rates of marginal sperm quality sires; (2)
Volume semen production created a preference for sires who will serve
the same animal repeatedly and deplete their semen reserves at collection
frequency.
In a natural service environment, the preferred bull
behavior would be to serve the cow in heat
once and then walk away, seeking the next cow in heat. This means the bull holds semen in reserve
for a potentially next cow in heat the same day, and does not expend his
systemic energy in those repeated mounts that, in a herd setting, lead to a
loss of body condition followed by a loss of libido.
AI is not fond of such sires, because they do not want
bulls that have to be collected daily to harvest all the semen they can
produce. This interferes with their
full schedule of collection and processing of a larger stable of bulls. Has this had negative fertility
consequences? To date, no one knows. But the documentable fact is that sire
conception rate (SCR= bull semen
fertility) and daughter pregnancy rate (DPR= cow fertility) are not very
highly correlated.
Are such bull behaviors
genetically linked? Yes, because to some extent all points of
deviation (measurable difference) among animals within a herd are definable as genetic
differences. But as these
differences were not important to AI success, they have never been summarized
and evaluated. Thus they remain within
the realm of observational knowledge—the sort of data scientists
distrust on the basis of limited sampling sizes (most people are not making
useful observations of their cattle, or at least fail to write them down for
future collation, or fail to submit them to an “official” summary).
The beef breeding industry
routinely tests bull behavior by summarizing the percentage of cows each bull
“covers” in a specific time period when turned out for range service. Generally, we know that beef breeds seem to
have more fertility than dairy cattle.
Part of the real reason would be that more attention is placed on fertility
as a desirable selection trait, and that a multiple of measures both
male and female are collated to estimate genetic fertility ability.
Successful fertility implies
a living calf. The beef guy
knows this, as his income is based on the size of his calf crop first, how it
grows after birth is a secondary level of income stimulation. Likewise it is true for the pig farmer
(litter size, livability of the piglets, sow acceptance of piglets for nursing)
and for the sheep farmer (live lambs, even when twinning, means more income
than dead lambs). But for some
perverse reason, an earlier generation of dairy geneticists (active in the
formative era of AI and the key promoters of composite index ranking) seemed to
have overlooked the link from reproduction to production—choosing to focus
purely on comparative lactation production.
This is where most of our issues with unsuccessful fertility in modern
dairy cows originated.
Thus ease of calving in an
indirect sense, as it correlates to both cow survival and calf survival, is
also linked to cow fertility.
You now have several points from which to decide how “useful” your cows
are in a genetic sense of potential transmitting ability. I would not save a bull from any cow who
has a history of difficulty in calving or of presenting stillborn calves. In all of animal agriculture, income
derives from reproduction, as the precursor to measured production. Keep that in your focus.
Successful fertility is
positively linked to production profitability. This is where the statistical data on
which sires have been ranked leads us astray. Think about your own dairy operation: is
it actual pounds per cow per day that determines your milk check income,
or is it predicted lactation pounds in 305 days? You might think the two are essentially
the same—but they are not.
I have a friend with purebred
Jerseys whose selection focus has consistently sought two things: higher
component %s (butterfat and protein) to drive his income, and annual calving
intervals over multiple lactations (cow lifetime totals) to drive his
profitability. We will analyze his
results:
He currently has a herd average
just shy of 17,000 pounds of milk with 5.6%bf and 4.0%pr—thus 950 pounds fat
and 680 pounds protein (on an ECM basis, this matches a 26,000# Holstein
herd). But the amazing thing is he
averages nearly a 12 month calving interval on sixty milking cows at this
level of nutrient energy conversion—a truly “elite” level of performance, as we
will demonstrate.
He has a neighbor milking 120
Jerseys, with a 20,000 pound DHIA herd average, whose annual milk shipments are
nearly exactly twice what Phil ships.
Why, if Phil’s cows are producing at the same level as a 20,000-pound
herd, is he only getting lactation credit for a 17,000-pound herd?
The difference is—his neighbor
accepts a 14 month calving interval as a consequence of a preference for
“high peak day” genetics over “persistency” genetics. He not only uses AI sires, he uses those
of the “high PTA milk” persuasion—those who daughters are predicted at higher
lactation pounds in 305 measured days, but whose reproduction is delayed (thus
total lactation is 365 days).
17,000 pounds of milk in 305 days
equals 55.74 pounds of milk actual per day.
20,000 pounds of milk in 365 days
equals 54.79 pounds of milk actual per day.
For three decades we have been
taught the rolling herd average was your measure of success in
dairy.
RHA is calculated as average test
day pounds times a 365 day year. But
we kept on calculating bull evaluations on a 305 day lactation value –
and in Mature Equivalent, not actual pounds.
This created a selection
preference for a higher peak lactation curve (in which that peak could extend
as a consequence of slow or defective fertility) over a flatter, more
persistent lactation curve (which is ultimately the most profitable, ie, persistency
of production meant fewer below-cost stale days at the end of the lactation,
thus a controlled-length dry period).
Earlier feeding approaches
also expressed a preference for delayed fertility. In the 1970s and into the 1980s (a
very important transition period in genetic evaluation concepts) the standard
nutritionist’s approach to feeding cows
was to “challenge feed” fresh cows—an added pound of grain for each three
pounds of milk, and see how high she will “peak”, on the assumption that a
higher peak will then carry her steadily declining daily yield further into the
end of the lactation, when actual production did not always cover total feed
costs. We were taught that a “good”
cow makes half her total lactation in the first 130 days, and that pregnancy
would make her yields drop, eventually into a “loss” column, at which point you
dry them up (no matter how many days until the next calving).
This was a strategy designed to
sell more grain (and grain was cheap and plentiful in those days, so why
not? The grain ration could make up for
a deficient forage base). The sort of
cow that makes milk out of grain, of course, had to be sorted from the cow that
gains weight from added grain. Thus in
genetic selection, we redesigned type standards to prefer the more “angular”
cow over the easier conditioning cow—and along with that, accepted a longer
period of “negative energy deficit” in the early months of lactation, thus
delaying the reproductive response.
These changes in cow structure and performance began slowly (usually
masked over by a steep decline in bf% tests, not considered important in that
time period as “fluid” milk was preferred over “manufactured” milk products in
a society obsessed by “low fat” —the loss in bf% a consequence of internal
energy rationing by cows).
On the genetic side, while thinking
in PD pounds, we were actually selecting genes that regulate the conversion of
energy intake into four bodily uses: production,
reproduction and health maintenance.
The genetic anchor to fertility
was lost when the high-indexing young heifer replaced the long-lifetime
production cow as the “bull mother” of choice. Long lifetimes were not possible without
fertility – but a “hot” first lactation is more easily made in the absence of
reproduction. Thus, if reproduction is
no longer a drag on energy intake, then we could select for higher levels of
protein %, and still have an increasing volume yield plane. As long as we introduced OvSynch, we could
continue to get at least some cows rebred, and stay focused on pushing the
envelope for individual cow yield volume.
The purebred sector focused on
producing AI sires uniformly adopted “induced” fertility—ie, super ovulation
and embryo transfer. The natural
fertility of these “hot” young first lactation cows was never tested, because
“induced” fertility could produce more than a lifetime of calves within two
years of embryo marketability. (No
one ever considered this may not be the fertility preference of typical
dairymen—as usual with newer technologies, we assumed they rendered traditional
ways “obsolete”.)
For too long, the genetic
community patted itself on the back for increasing the “base change” for milk
yield in every breed (every five years, as adjusted by USDA) – until it was
clear that dairymen were not always happy with the higher costs of
reproduction, slower success of reproduction, producing a faster herd turnover,
and in many cases a shortage of replacements.
Some tried crossbreeding as the “solution” to restoring “vigor”—others
just quit AI and reverted to natural service.
Neither of these have to date altered the overall cost of production,
thus milk production profitability remains marginal.
Genes truly lost can never
be replaced. One of the
consequences of the “index” era has been a rapid destruction of bloodlines,
followed by a decline in sireline variety.
All AI sires today are related to each other on a passive level, but the
“linebreeding” of any sire line to develop a more homozygous pattern in trait
transmission is avoided due to phobias over “inbreeding”. Thus it is more difficult to create
heterozygous variation within a purebred population, otherwise known as “hybrid
vigor”—and it is more difficult to sustain “hybrid vigor” within a crossbreeding
scheme, due to the lack of patterns of homozygosity unrelated to other breeds
(able to produce heterozygous variation) when crossed.
Basically, “genes” are either
present or absent in the DNA. Genes
do not “dilute”. If the cow lines
most superior for fertility or health maintenance have been culled from the
population (on the basis of being “noncompetitive” under prior single-trait
index rankings, as bull mothers) (on the basis of plain old “old age” culling
them form the breeding herds) – their genes are lost. Thus the blithely stated assumptions that
“all you need are plus DPR and plus PL sires to restore prior levels of
fertility” both overstates the genetic ability of current AI sire lines and
understates the time and culling rates needed to recapture prior levels of
performance in these traits.
But the lesson of my friend Phil’s
Jersey herd—in which homebred sires comprise half of the ongoing sire
selection and their selection is based upon rigorous adherence to desired
trait levels—proves that it can be done…
IF you stay focused.
