Cattle Today

Cattle Today



Parasites may be little, but they can cause big problems for beef producers. Gary Sides, nutritionist for Pfizer Animal Health, said the pests cut profits in many cattle operations.

“When you look at parasites from a nutritionist's standpoint, they do two things that are really detrimental: depress feed intake and depress digestibility of the feed cattle do consume,” he said. Sides spoke at a seminar cosponsored by Certified Angus Beef LLC (CAB) last fall.

“When an animal has decreased intake and/or digestibility, one of the first places it shows up is in marbling score,” he said. Sides explained that as energy intake drops, so does marbling potential. Even suckling calves that are creep fed or early weaned have a potential for improved marbling at slaughter versus their herd mates that are weaned in the traditional manner.

“The calf on a lower plane of nutrition has enough energy for maintenance and for moderate lean muscle growth,” he said. “The next step in energy deposition would be marbling.”

It's important not to let energy level drop too low. “There's no compensatory marbling,” Sides said. It makes sense to prevent parasites from sapping energy meant for growth and marbling.

Although feedyards may deworm calves, he said the process should start on the ranch.

An Oklahoma State University study compared calves never dewormed to those dewormed upon arrival at the feedyard. A third group included calves dewormed both at the ranch and at the feedyard.

“Those that were dewormed picked up 48 pounds of gain on grass,” he said. “In the feedyard, more than 80 percent of all the pulls came from cattle not dewormed on grass.”

In the end, those calves never dewormed showed a 26 percent reduction in percent Choice, and gave up 96 pounds of gain compared to calves dewormed at both the ranch and the feedlot.

“That's a huge effect,” Sides said.

Producers trying to stretch the recommended dosage may also give up carcass quality. Private research by feedlot veterinary consultants took calves that were all dewormed (with an avermectin pour-on) during the backgrounding period, and then assigned to one of three treatments during the finishing phase: no dewormer, a half dose Dectomax injectable or a full dose of Dectomax injectable.

The control group with no dewormer at the feedyard graded 36 percent Choice, while those treated with a half dose picked up just two percentage points. The full dosed cattle graded 52 percent Choice and picked up an additional 22 lb. in carcass weight over both the control and half-dose treatments.

“Even minimal parasite infections can have a huge effect on the animal,” Sides said. One decision that might appear insignificant is whether to use pour-on or injectable dewormer. Results can be noticeably different.

“If I want to kill internal parasites, which is our number one economic loss from cattle parasites, then I prefer an injectable dewormer,” he said. “In the south [injectables are] pretty common. Up north, a lot of pour-ons are used and I think they give up some performance because of it.”

The bottom line, Sides said, is that producers need to worry about the little things— lice, worms and grubs to be exact. But the biggest economic loss from these comes from abomasal worms.

For information on this topic, or to see others related to quality beef production, see the Feeding Quality Forum proceedings available at


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