First in a roundtable series.
The health of feedlot cattle, especially those that are newly-arrived to the operation, is influenced by many things. Before cattle even step on the truck, their immune status can determine how they are going to respond to this next phase of production.
Today’s calves are often bigger but younger on arrival than in years past, and many believe their immune systems are also more immature. Some believe feedlot calves today are different than in years past as far as immunocompetence. Tom Portillo, DVM, Amarillo, Texas, says, “We’re dealing with a different animal and it’s being treated differently in the feedyard. A seven-weight now is not the same animal that used to hit a feed yard 20, or even 10 years ago. They don’t have the immunocompetence that they used to have. We have a more immature animal, thus we’re dealing with a much more immature immune system. They used to be a lot more hardy on arrival.”
Portillo believes people chase heavier weaning weights and wean a more immature calf, and sometimes the immune system of the calves gets lost in the wake. Nate McDonald, DVM, Cattle Health Management Network, Meade, Kan., agrees and says as weaning weights have increased, ages have come down and a lot of 14-month-old cattle are now slaughtered.
Dan Goehl, DVM, Canton Veterinary Clinic, LLC, Can ton, Mo., says even in small groups of well-immunized calves, stress and commingling can “undo” immune status. Goehl was involved with a marketing alliance in Missouri where they were commingling weaned, double-vaccinated cattle. “The morbidity was higher than I would have ever thought it would be,” he says, “because we took multiple groups of five or 10 head from multiple producers and put them together. It was just too much challenge for the immune system.”
Portillo believes sometimes too much weight is given to the role antibiotics play, to their credit or discredit. “Antibiotics are only a part of the situation,” he says. “We can rely on them too much. Basically, all they do is clear – or kill or stop – bacterial proliferation. The immune system still has to go in there and clear up the mess.”
Obviously, we do have a lot of immunocompetent animals or the production system wouldn’t work. “The majority of them are or we wouldn’t be in business, we wouldn’t be profitable,” Portillo states. He adds that all cattle reaching finish weight and shipping are immunocompetent for the most part.