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CATTLE TODAY

HUNTIN' DAYLIGHT -- BATTLING THE UNKNOWABLE IN STOCKER CATTLE

by: Wes Ishmael

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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