The numbers released quietly by the federal government this year were alarming. A ferocious germ resistant to many types of antibiotics had increased tenfold on chicken breasts, the most commonly eaten meat on the nation’s dinner tables.

But instead of a learning from a broad national inquiry into a troubling trend, scientists said they were stymied by a lack of the most basic element of research: solid data.

Eighty percent of the antibiotics sold in the United States goes to chicken, pigs, cows and other animals that people eat, yet producers of meat and poultry are not required to report how they use the drugs — which ones, on what types of animal, and in what quantities. This dearth of information makes it difficult to document the precise relationship between routine antibiotic use in animals and antibiotic-resistant infections in people, scientists say.

Advocates contend that there is already overwhelming epidemiological evidence linking the two, something that even the Food and Drug Administration has acknowledged, and that further study, while useful for science, is not essential for decision making. “At some point the available science can be used in making policy decisions,” said Gail Hansen, an epidemiologist who works for Pew Charitable Trusts, which advocates against overuse of antibiotics.