SELECTIONS - Spring/Summer 2001
Where Does A Circle Begin?
By Mel DeJarnette, reproductive specialist
Where does a circle begin? We all know that round or
spherical objects don’t really have a beginning or an
end. We may often try to assign a beginning and end, but
these designations tell us more about our orientation to
the object than they do about the object itself.
The same is true for cycles. Cycles are a series of events
that repeat themselves over time. A couple of cycles that are
of particular importance to beef and dairy producers are estrous
cycles and reproductive cycles.
Estrous cycles are the result of a repetitive series of hormonal
communications between the ovary, the brain and the uterus that
ultimately cause the cow to show estrus every 21 days. Because
standing estrus is the only outward visible evidence that estrous
"cycles" are occurring, we have arbitrarily assigned the day of
estrus as both the beginning and the end of the estrous cycle.
The estrous cycle is but one component of a much larger cycle
called the reproductive cycle. The reproductive cycle is the
series of events that result in animals repeatedly conceiving
and producing a live calf, hopefully, on a 12- to 13-month
interval. The reproductive cycle not only includes the period
of estrous cycles, but also gestation, lactation, the dry period,
calving and the period of postpartum anestrus.
Flat Tires And Reproductive Management Programs
Sometimes round objects get flat spots that cause them to not
function properly. I saw this often in one of my summer jobs as
a youth, changing tires in a filling station. The funny thing
about flat tires is no matter where the leak, they always go flat
on the bottom. Reproductive management programs are very similar.
The "leak" could be anywhere in the management program but it always
goes "flat" at pregnancy check.
When you find yourself with a nail-induced flat on your pickup,
you immediately begin to speculate as to where you picked it up.
Usually the last place you went will take the brunt of the blame.
"Must have been when I went over to Farmer John’s yesterday; that
place is always a dump." However, reality is, that nail probably has
been there for quite a while, but only recently leaked enough air to
cause the tire to go flat.
The same is true with reproductive management programs. When pregnancy
checks aren’t so good, we often immediately lay blame to recent events
(the heat detector, the inseminator, the synchronization system, the
semen, etc.). However, in reality, we probably picked up the nail
long before that. Let’s discuss the primary hazards on the reproductive
highway and how to avoid "flats" in your management program.
Fresh Cow Problems
The "fresh cow" segment of the reproductive highway is a pothole-filled
stretch of road. Cows with postpartum metabolic disorders, such as milk
fever, ketosis and displaced abomasums, are much less likely to settle
early in the breeding period than "normal" cows. Other abnormalities,
such as retained placenta, difficult calving, metritis, cystic ovaries
or poor body condition, are also associated with reduced reproductive efficiency.
Early identification and early treatment of fresh-cow problems are critical
to minimizing economic losses associated with these disorders. This
requires intense observation of fresh cows to identify potential problems
while they are still minor, and a standard set of procedures to treat the
problem cow once identified. Otherwise, minor problems become major ones
before they are identified, and major problems can become outright
catastrophies before they are treated.
This is a key concept in the reproductive management platform developed
by Pharmacia Animal Health called "The 100-Day Contract." The system
prescribes an intense protocol of fresh-cow observation, temperature
monitoring for 10 days post calving, and a standard operating procedure
for therapeutic treatment of problem cows to nip problems in the bud
before they fester into huge economic parasites.
The Dry Period
The dry period is such a serene, quiet and apparently uneventful
stretch of road that it’s hard to believe there could be any problems
nearby. The dry cow is often set on cruise control and forgotten.
However, the road through the dry period has several forks. If you get
too relaxed and miss your turn, you may find yourself on a very
dangerous stretch of road.
As mentioned earlier, cows that develop health problems in the
postpartum period are more difficult to get rebred. Table 1 suggests
that cows that develop milk fever, which is a disease associated
with inadequate dry-cow nutrition and management, are more likely
to develop one or more of several other postpartum disorders. Therefore,
a poor dry-cow program may send you through the fresh-cow period on a
road covered with nails and broken glass as well as potholes.
Watch for Road Signs
The alert driver will watch for road signs. One of the most obvious
road signs the dairyman can follow is body condition. We know cows
will lose weight and body condition after calving, and there is nothing
we can do to prevent it. Therefore, it’s extremely important that cows
are in optimum body condition when they calve so they’ll have energy
reserves to pull from when needed.
We also know we don’t want to make any significant changes in body
condition (up or down) during the dry period. Therefore, we must dry
off cows in adequate body condition (3.25 to 3.75) and maintain that
level until calving. This problem is complicated by the fact that cows
will decrease dry matter intake by 20 to 30 percent in the weeks prior
to calving while energy demands from the growing fetus increase
exponentially. This means the energy density of the ration must be
increased during the two- to three-week period prior to calving.
Also, it’s important that every cow be in the acceptable range of
body condition at dry off (3.25 to 3.75), and not just the herd
average. If the herd average is 3.25, about half your cows will be
below 3.25, and many will be below 3.0.
And finally, since body condition at dry off is so critical to
dry-cow nutrition and postpartum health, the single most important
time for you to evaluate body condition is 60 to 90 days prior to
dry off. This gives you time to alter the late-lactation nutrition
program, if necessary, to keep the reproductive management program
on a smooth road.
Road Side Assistance
Whether it’s a flat tire or a missed turn, sooner or later we all
find ourselves in need of a little assistance. On the highway, you
can always count on AAA. On the reproductive highway, count on
double S — that’s Select Sires. Our professional, experienced
staff is eagerly waiting with products, services and technical
expertise to get you back on the road. Give your local Select Sires
representative or member cooperative a call anytime we can be of assistance.
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