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Drought-Stressed Calves Present More Health Challenges Than Usual

Drought-Stressed Calves Present More Health Challenges Than Usual
Calves arriving at stocker operations and feedlots this fall could present more health challenges than usual.

“This year is not the normal routine,” says Shaun Sweiger, DVM, a feedlot and stocker consulting veterinarian in Oklahoma, who has a part-time teaching appointment in beef production medicine at Iowa State University. “Producers in drought areas tried to hold on as long as possible. A lot of plans that would have been put in place weren’t.”

The result is that more calves moved at lighter weights and younger ages than normal, both of which are invitations to added morbidity.

But, even without cattle moving due to the drought, these are not routine times. Feedlot placements continue heavy as a result of dwindling calf supplies spawned by the nation’s contracting cowherd. Here again, younger, lighter cattle are moving to feedlots sooner.

If you’ve ever stockered or fed cattle, you know there’s an inverse relationship between calf weight and health; the lighter they are, the higher the morbidity and mortality.

In one extensive feedlot survey from a couple of years ago, Larry Hollis, DVM, says, based on the in-weight of cattle, the mortality rate was: 3.25% at 400 lbs.; 2.5% at 500 lbs.; 1.75% at 600 lbs.; 1.0% at 700 lbs.; 0.8% at 800 lbs. Hollis is a Kansas State University professor and extension beef veterinarian specializing in feedlot and stocker cattle.

Between the younger mix of cattle, the drought and this summer’s excessive heat, Nate McDonald, DVM, says he was already seeing more health challenges than usual by the second week of September. He’s a feedlot and stocker veterinarian with Kansas-based Cattle Health Management Network.

If calves moving from drought areas are in good shape, Hollis says they shouldn’t present more than typical health risk. If they were under nutritional stress when they left, though, it could be a different story.

“Protein drives the immune system. If they were in poor shape, they’ll have more health problems because they didn’t have the nutrition necessary to drive the immune system,” Hollis explains.
Likewise, Sweiger says, “If calves (in the drought area) went to a good home and had some gain put on them – backgrounded, if you will – and resurface in the fall market, the health challenges should be minimal.”

More important than vaccines

In the best of times, Hollis would rather have cattle that can eat and drink when they arrive, rather than with any sort of vaccinations in them.

“It’s hard to get newly moved cattle to eat and drink. If you can offer them something highly palatable on arrival, that’s the best thing you can do. That part of preconditioning – teaching them how to eat and drink – is more important than the vaccines they receive,” Hollis says. “Calves will be exposed to some of the pathogens they’re vaccinated for, but all calves need to be able to eat from a bunk and drink when they leave the farm or ranch.”

If cattle are nutritionally stressed, McDonald says, “Don’t step up the rations too fast. Give them time to acclimate and build some rumen capacity.” This fall, he’s also adding chloratetracycline to rations for five days to help get a jump on health problems.

Hollis adds, “One thing many people overlook is that if those cattle haven’t eaten anything green in a long time, they’ll be deficient in Vitamin A, unless they’ve received it in a supplement.”

Nonetheless, depending on the supplement, cattle could still be deficient in Vitamin A. Hollis uses the example of Vitamin A-fortified range cubes. If those cubes were held too long in too much heat, Hollis says the Vitamin A denatures.

Among other things, Hollis explains, “Vitamin A affects the lining of the intestines and lungs. That makes young cattle deficient in Vitamin A more susceptible to scours, and cattle of all ages more susceptible to lung-related infections.”

Incidentally, Hollis says Vitamin A also affects the uterine lining, making it more difficult for heifers and cows deficient in the mineral to breed back.

Hollis emphasizes, “Vitamin A is dirt cheap and often overlooked when it should be one of the first things considered for cattle coming out of drought areas.”

Watch trace minerals

Similarly, McDonald says trace minerals can be deficient in nutritionally-stressed cattle. He explains copper is often deficient in stressed forages. Copper access can be inhibited by other trace minerals like molybdenum, too. Trace minerals necessary to immune function also include zinc and selenium. McDonald advises providing a balanced trace mineral supplement.

Of course, drought-forced early shipment altered more than available nutrition. The drought disrupted normal ranch health programs, too. Some calves that would normally be vaccinated at weaning and/or ahead of shipment, undoubtedly missed that opportunity. That increases the opportunity for health stress or risk.

“Anytime we increase cattle stress and negatively affect the immune system, that allows bugs to rifle through them,” Sweiger says.

“If there was ever a time to consider metaphylaxis on arriving cattle, this fall is it,” McDonald adds.

The same goes for other intervention opportunities.

For high-risk calves, McDonald often finds benefit in having an intranasal vaccine administered prior to shipment, in order to stimulate interferon production. For lightweight calves, he’ll also administer metaphylaxis pre-shipment, as well as an autogenous vaccine.

“It gives me more latitude for processing between shipment and arrival,” McDonald says.

McDonald wants cattle fully hydrated prior to processing. Along with reducing stress and other health implications, he explains, “The injection site in a dehydrated animal remains open longer, allowing more product loss. Plus, hydration allows the vaccines to be processed by the immune system more efficiently; the cattle we manage this way pre-shipment perform better for us.”

If cattle can be put together in a day or two, Hollis wants them shipped. If it takes longer than that, he’ll consider pre-shipment an intranasal vaccine or metaphylaxis.

Consider cattle history

“What you do on the front end depends on the cattle you’re dealing with and how long it will take to put them together,” Hollis says. “It all depends on the history of the cattle and what they’re going through at the time.”

Even when pre-shipment strategies make sense, Sweiger says that “unless you have a strong relationship with the supplier, you’re leery of whether or not it was done. If it was done, you’re wondering whether or not it was done appropriately.”

Hollis cautions that it’s a matter of trust between the customer and the order buyer assembling the cattle. He works with one stocker operator who’s dealt with the same order buyer for more than a decade. They discuss every set of cattle. If the stocker producer wants to utilize pre-shipment health protocols, he knows they’ll be administered correctly.

But, if the buyer represents a new or short-lived relationship, Hollis says, “I don’t know if they’ll give the full dose. I don’t know if they know how to handle a modified-live vaccine without killing it. Once I have a chance to visit the facility, meet the people and watch them work, I have more trust.”

Thoughts on PI testing

Testing cattle for the persistent infection (PI) of bovine viral diarrhea virus (BVDV) is another matter. All three veterinarians say testing pays dividends. McDonald says PI-testing after arrival is good, testing prior to shipment is better, and testing them before they ever get into the market is best.

“I would sure do it with a new source of cattle. You don’t have to find many PI calves to make the cost of it pay,” Hollis says. “It’s cheap enough on a per-head basis. Especially with the value of calves today, you can’t afford to leave a PI calf in the pen.”

TAGS: Nutrition