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Great Expectations

An epidemiological approach to treating stockers can balance realistic control and response rates against true cost, but it takes time and records.

This will make you pull your hair out. Based on the pull rates of several million head of stocker and feeder-weight cattle over the years, Dee Griffin says morbidity rates seem to always hover around 15%.

The perfect set of low-risk calves might run 12-15%, while the sorriest set of trade bait walking, which should run 100%, will on average only have 15-20% pulled for treatment, explains Griffin, a veterinarian recognized industry-wide for blending common sense with science in treating stocker and feeder cattle. He's also a professor of beef cattle production management at the University of Nebraska.

Griffin has a theory on why this is, which we'll get to, but the fact underscores vexing questions common among backgrounders and stocker operators. These include: How much sickness is too much? How much response rate is too little? And, how much money should you pour into treatment, and when, to know whether or not the strategy is both effective and cost effective?

At least part of the answer lies in the fact that although endemic challenges like bovine respiratory disease (BRD) occur at a variable rate, they have a predictable pattern. That's why you expect a percentage of each load of calves to break with BRD. The percentage will vary, but you know up front that the pathogens involved, and the stress on young cattle during the marketing and delivery process, means you'll see it.

This is epidemiology in a nutshell — understanding the cause and incidence of disease from the standpoint of entire populations.

Managing Source Is Key

“I suppose the non-epidemiological approach is where everybody starts,” Griffin says. “You have to start someplace, so you put together treatments that make sense based on historic problems, isolations of specific pathogens, the timing of them, and sensitivity of pathogens to certain products in the past.”

So, everybody starts with past experience, common sense, hope and, hopefully, an understanding of what Griffin terms the “three S's of disease” — source, source and source.

“You put together cattle, commingle them, that's a source issue. The stress associated with transportation and distance in delivering cattle is a source issue. The timing of when cattle are available that fit a particular breakeven pattern is a source issue, too,” Griffin says. Consequently, minimizing a challenge like BRD begins with managing these source issues.

Immunological preparation of cattle via preconditioning programs is one example. So is working to reduce the time stress of procurement and delivery.

“From an epidemiological standpoint, we know precisely what the pathogens are and what the sources are. All we don't know on a set of calves is how well-prepared their immune systems are,” Griffin explains. Consequently, he says the industry relies on receiving programs as the first line of defense.

“I don't think you can afford not to mass-medicate off the truck if they're put-together cattle, high-stress cattle or both,” he says.

Moreover, Griffin is adamant that what people believe to be animal health product failure is usually human failure.

“With the drugs available today — the best the industry has ever had — failure of response is not failure of the drug. It's our failure to give the drug a chance to work,” he says. “When drugs don't work, it's usually a matter of the immunological preparation of the cattle and/or the timing of therapy.”

In fact, time continues to be the primary disease weapon over which producers have some control.

Griffin points out that cattle — as prey animals — have a genetic heritage to hide illness. “The cattle have to get to know and trust us so they'll be less likely to hide disease symptoms from us for as long,” he says.

Beyond that, Griffin emphasizes: “The only other ace is to pull the trigger quick, and the best trigger you can pull is to intercept the pathogenesis with mass medication coming off the truck.”

Once infected, time of treatment is crucial. Since at least 10% of pulls won't respond to first treatment, Griffin suggests using long-acting antibiotics, and he never returns cattle to their home bunch the first day. He keeps them in the hospital. If they're improving on Day 3, he gives them a second round and sends them home. The industry has found this four-day approach increases response rate and reduces re-pulls, but the economics of this approach must be considered.

Value Of Deads And Records

Griffin says taking an epidemiological approach to fighting disease begins with finding out why cattle die and keeping records to build specific knowledge.

“You need to take a hard look at cattle that die. They might be the most valuable cattle you've got because they can help you evaluate timing effects, whether the treatment you've used is appropriate for the bugs isolated, and how that compares to what others are seeing,” he says.

He adds that necropsy and culture results obtained from diagnostic labs offer little or no help in treating existing groups of cattle. But the data helps make better decisions down the road.

Next, come the records. Real epidemiology requires loads of observations of cattle that exist in the same population. Think in terms of 4-weight Holstein steers from a particular part of the country and stockered during a particular season, rather than 4-weight cattle in general. Such data is invaluable, but acquiring it takes lots of years, even for the largest operations.

That said, Griffin believes there are records producers can use to their benefit along the way. In addition to traditional kinds of group records, such as source, supplier, in-weight, shrink, individual records for each head pulled and treated, etc., Griffin recommends keeping a daily weather log.

“Producers should record the daily high and low temperatures and a description of the weather conditions that day,” Griffin says. It helps put pulls and response rate in context.

Griffin also cautions: “The only objective hospital cattle data we can collect is their temperature, but that can also be our Achilles' heel.” Since time of day can affect cattle temperatures by 2° F, and cattle sickest the longest will typically have lower temperatures than those just breaking with a disease, Griffin suggests using temperature to gauge disease progress, not whether cattle should be treated if pulled to begin with.

He recommends pen riders use their eyes and experience to pull cattle, then score them on a 5-point scale, with 1 being “just in case,” and 5 being, “Lord, I doubt he'll make it to the hospital.”

“I believe you should score cattle independent of the thermometer because all too often people let the thermometer do their thinking for them,” Griffin says.

Response Rules Of Thumb

Even when everything is done just right, about 15% are going to end up sick. Griffin believes the logic-defying similarity in morbidity between low-risk calves and high-risk ones — based on closeouts — boils down to human nature. He contends pull rates for low-risk cattle are artificially high because folks will often pull and treat cattle out of habit, rather than actual need.

But, Griffin notes that more than half of high-risk cattle have lung lesions at the packing plant — an indication of respiratory pneumonia — compared to 20-30% for low-risk cattle.

“A thumb rule I've used for 20 years is that if 18 of 20 head pulled are getting better (90% response rate), then I'm doing a good job. Below 90%, I either have the wrong therapy or, more likely, I got a late start because of a source problem,” he says.

He adds that of the non-responders, he expects 10-20% mortality (equivalent to 1-2% respiratory death loss overall).

“Anytime I'm consistently experiencing death loss more than 2%, I most likely have a source problem. That's when epidemiology and the economics of its application to the correction kicks in to high gear,” Griffin says. “I think we know enough about disease, and have good enough animal health products, that we can accomplish that provided the source-related health problems don't dig the grave.

“Epidemiology can help clarify the value of money spent on cattle and their cattle health problems. Throwing dollars at processing and treatment won't fix source-related health problems but, on the other hand, a profit opportunity can be missed trying to starve, discount or penny-pinch cattle,” he adds.

Finally, Griffin figures spending 6-8% of the animal's purchase cost for treatment, excluding processing costs, is the outer limit.

“You've got to know when to let them go,” he says. “My regimen is to give them two rounds of therapy, then if they're improving, it's between them and God.”

Mass Med Math

As far as Dee Griffin is concerned, decades of research support the fact that metaphylactic treatment (mass medication) of feeder- and stocker-weight cattle upon arrival significantly reduces the number of pulls and subsequent re-pulls for bovine respiratory disease.

“There's no question mass medication works,” says Griffin, a veterinarian and University of Nebraska professor. The only question about metaphylaxis is whether the gains it offers will provide a net economic return in a particular situation. And, that boils down to simple math, including the cost of lost performance.

“If metaphylactic treatment costs $10 per head, and if you're planning to put 200 lbs. on cattle in the stocker pasture, then the treatment adds 5¢/lb. to the cost of gain,” he says.

But, say you figure that without such treatment you'll have 20% morbidity in a group of 100 head, $20/head treatment cost. That's the equivalent of $4/head or $2/cwt. of gain.

At first glance, doing nothing seems economically prudent. But, Griffin says, “You can also expect any calf that gets sick to lose 28 days' worth of gain. So, it's reasonable to expect a calf that got sick to weigh 30 lbs. less than one that didn't get sick.”

Thus, 30 lbs. at $90/cwt. for a seven-weight calf is $27. Across 20 calves that's $540, or about $2.80/cwt., added cost to the entire group. So, factor in the lost performance and doing nothing costs $4.80/cwt., vs. $5/cwt. for treating cattle on arrival.

Obviously, this is a simplistic scenario. Outcomes will vary by actual metaphylactic cost, morbidity rate, treatment costs and response rates, how many of the sicks turn out to be re-pulls and chronics and so on. The point is when figuring the cost of a preventive treatment like metaphylaxis, producers must also consider the price of lost performance — the opportunity cost — of ignoring preventive treatment.