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RIDING THE GAP
Battling the Unknowable in
Stocker Cattle |
By Wes Ishmael |
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 You
can’t vaccinate for it or treat it effectively if you have it.
Consequently, the most effective management practice when it
comes to mycoplasma is simply avoiding it, though that’s not
possible either.
That’s the frustration faced by stocker operators and others who
end up dealing with mycoplasma—unresponsive pneumonia and
arthritis.
Mycoplasma has been around since at least the mid 1970’s,
according to researchers, though you didn’t hear much about it
until about 25 years later when it seemed like everyone was
having problems with it. There’s been less chatter about it for
the last couple of years, but there’s no way of knowing if
that’s because the incidence is any less, or if folks
experiencing it are more informed about what it is and what to
expect.
Either way, with the fall run of calves in full swing, it’s
worth remembering what is known and unknown about the disease.
How Mycoplasma Looks
Part of the frustration with mycoplasma is that it’s difficult
to distinguish from other maladies stemming from Bovine
Respiratory Disease. As researchers at Kansas State University (KSU)
described it for a mycoplasma survey: “About two weeks after
arrival, calves pulled for treatment of pneumonia don’t respond
to treatment (no improvement after trying two different
antibiotics). Calves are often eating well but those being
pulled are depressed, have clear nasal discharge and often seek
shade. About three weeks after arrival, arthritic calves are
being pulled. Lameness may not always appear in a group, but if
it does, the calves exhibited lameness and joint swelling in the
knee, elbow, hip or fetlock joints and several joints may have
been involved at one time. The conditions are progressive with
affected calves ending up thin, dehydrated and depressed. Most
death losses are occurring between three and six weeks after
arrival. By about six to seven weeks after arrival, the outbreak
stops with little additional sickness and death loss.”
Most researchers feel that the organism is an opportunist that
leaves the nose and throat of calves during periods of stress,
nutritional deficiency and/or while an animal has a suppressed
immune system caused by an infection of another organism. One
reason mycoplasma is so difficult to treat, say the researchers,
is that the organism has no cell wall; many antibiotics today
attack the cell wall of organisms. That’s also why it’s been
tough to come up with a vaccine against it. “As mycoplasma
appears to be an opportunist occurring most frequently during
times of stress or when a calf’s immune system is weakened,
management programs should focus on those procedures that can
get calves started out in the right direction,” explain the KSU
researchers. That’s one reason KSU (Spire, Blasi, Sargeant,
Rosenbusch) conducted a survey of stocker operators a few years
back, trying to get a handle on how widespread the disease was
and what procurement and management practices might be related
to it.
Key Survey Findings and Recommendations
• The syndrome was reported across all sizes of operations, but
as operations get bigger, they were more likely to have a
problem. With that in mind, the folks at KSU suggest buying only
as many cattle as you can effectively handle. “It takes a pretty
good workday for one or two people to feed, check pens for sick
calves and pull and treat those calves. Add into the mix days
when you process a load or two, and it’s not hard to see why
everything begins to stack up.”
Furthermore these researchers say, “Cattle should be fed and
observed for sickness first thing in the morning. Watching how
calves rise and come to the bunk goes a long way in picking up
sick animals. Waiting until later in the day is a problem,
particularly if there is a wide difference in temperature from
morning to afternoon since most calves will have increased
respiratory rates that can mask signs of early
pneumonia…Additionally, cattle appear to better handle the
stress of handling for treatment and processing earlier in the
day than later in the afternoon or evening (Breazile, 1988).”
• The syndrome occurred in all weight classes of cattle, but is
more likely in lighter
weight cattle. Steers and heifers were affected about the same.
• As the number of loads received during the winter increased,
the more likely an outbreak was to occur.
Are you going to buy large numbers of cattle and find cattle
free of mycoplasma?
Probably not. "The organism is too wide spread,” say the KSU
folks. “As a simple recommendation, know your order buyer.
Cattle represented as cheap and too good to be true probably
aren’t in the long run. Buying stale, stressed calves increases
the likelihood of having cattle that respond poorly to
treatment. A significant finding from the survey was that cattle
buying practices do increase the risk of having cattle with
non-responsive pneumonia and arthritis. “Minimizing the number
of states you buy cattle from or at least sourcing cattle from a
single order buying facility, regardless of the state or region
of origin appears to help in reducing loads of affected cattle.
This appears particularly important for cattle brought in during
winter months."
• The likelihood of having a problem increased as cattle were
received from an increasing number of states.
“If an operator buys cattle from a single source regardless of
the region of the country (southeast, southwest, northeast) they
are less likely to have reported a problem than if they buy from
multiple sources across several states,” say the KSU
researchers. The syndrome was reported in loads of cattle from
all regions of the country, but loads from the western region of
the U.S. (Wyoming, Colorado, Utah, Nevada and California) seemed
less likely to be affected. Home-raised calves or those procured
in Kansas were less likely to have a problem.
• Minimize contact between arriving cattle and sick pen cattle.
According to KSU researchers, large numbers of mycoplasma
organisms are shed from nasal secretions of sick calves.
Consequently, they say exposing new cattle to the unnecessary
risk of contact with the organism should be avoided; utilize
separate sick pens and receiving or holding pens; clean and
disinfect hospital pen waterers daily. Researchers point out
disinfectant solutions of peracetic acid and iodophores have
been shown to be effective against mycoplasma.
• Get control of a respiratory disease early.
Though it may run counter to expectations, affected herds in the
survey were more than twice as likely to use metaphylaxis (mass
treatment of cattle before clinical signs appear). The type of
antibiotic used in either the metaphylaxis or treatment program
did not appear to be a reason for having the syndrome.
Researchers note, “The survey indicated a significant difference
in the frequency of use (metaphylaxis) on affected operations as
compared to operations not receiving affected loads. The
question begs to be asked, ‘Did it cause the problem?’ or ‘Did
they use metaphylaxis in an effort to prevent affected loads
because they’d had affected loads before?’ We were not able to
answer either of those questions. In the final analysis,
metaphylaxis did not appear to play a significant role, as data
suggests that within operations using metaphylaxis there didn’t
appear to be any relationship between affected loads and
unaffected loads receiving the procedure. Metaphylaxis is a
proven management practice to help reduce sickness, chronics and
death loss rates in high-risk cattle. Its usefulness has been
shown over many research trials, and it remains as a practical
management tool for targeted loads of cattle.”
• The use of modified live viral vaccines did not appear to be
the reason for a problem occurring. Since mycoplasma appears to
be an opportunist that attacks when calves are already stressed,
KSU researchers recommend doing all you can to minimize common
respiratory viruses such as Infectious Bovine Rhinotracheitis (IBR),
BVD, Parainfluenza –3 (PI3) and Bovine Respiratory Syncytial
Virus (BRSV).
“As clinical cases of BVD have been associated with increased
risk to mycoplasma infection, a BVD vaccine component should be
used in the receiving program,” say the researchers. “Based on
survey results, whether a modified live or killed BVD vaccine
was used, no particular vaccine program appeared to have an
advantage over another.”
• Increasing stress by castrating or dehorning may increase the
likelihood of having a problem regardless of whether the
procedures were done on arrival or delayed.
“If you can’t buy steers and clean-headed cattle, the KSU
researchers recommend delaying these procedures for about 30
days post-arrival,” say the researchers.
You can find other recommendations and the complete survey at
www.beefstockerusa.org |
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