Many industrial feedlots see routine use of antibiotics as essential. Some cattlemen disagree, calling them “performance enhancing drugs.”

Ben Holland holds a Mason jar, tilting it slightly to show the powdery 90 milligrams of the antibiotic tylosin inside.

“It’s about the amount that one animal gets in a day,” he explains, in a small factory that produces feed for 48,000-odd cattle packed in pens in Tulia, Tex., south of Amarillo. Nearby, rumbling steam towers turn corn kernels into flakes.

Dr. Holland is the director of research at Cactus Feeders, a feedlot giant. During a recent visit, I found myself surrounded by men with Ph.D.s and cowboy hats like Dr. Holland.  Several wore jackets bearing drug company logos that were sure to smell of steamed corn and flatulent cattle by day’s end.

Behind Dr. Holland, antibiotics were stacked in large bags rising to his shoulders. Every day, cattle here, whether sick or healthy, are given antibiotics in their feed.

But it’s an increasingly debated practice on industrial farms.