CHICAGO (Reuters) - Sales of medically important antibiotics in the United States for use in livestock jumped by 20 percent between 2009 and 2013, federal regulators said on Friday, although recent statements by producers suggest those figures could be dropping.

A woman waits at a meat counter in the Broadway Market in Buffalo, New York April 10, 2011. REUTERS/Eric Thayer

Between 2012 and 2013, the U.S. Food and Drug Administration said its annual report, domestic sales and distribution of antibiotics approved for use in food animals increased 3 percent.

Companies such as Tyson Foods Inc and Perdue Farms have said in the past year, however, they have either reduced or eliminated the use in chicken barns and poultry hatcheries of antibiotics used on humans.

“A lot of these announcements came in either late 2013 or in 2014, so we don’t really expect to see that reflected in the data we’re looking at right now,” said Gail Hansen, a senior officer for Pew Charitable Trusts’ antibiotic resistance project. “At some point, though, we should be seeing a decrease.”

What specific antibiotics are being fed to which animals, and in what volume and for what reasons, is not clear.

Trade group North American Meat Institute told Reuters it supports the voluntary guidelines FDA released in 2013 for drug makers and agricultural companies to phase out antibiotic use as a growth enhancer in livestock.

However, “it is hard to glean much information about what the (FDA) report means as far as the key issue of antibiotic resistance is concerned,” said Betsy Booren, the group’s vice president of scientific affairs.

Public health advocates, along with some lawmakers and scientists, have criticized the long-standing practice of using antibiotics in livestock, saying it is fueling the rise of antibiotic-resistant bacteria. Agribusinesses defend the practice, saying animal drugs are needed to help keep cattle, pigs and chickens healthy, and increase production of meat for U.S. consumers.

Though the FDA sales data is not current, Hansen said it will help federal regulators create a baseline for their current research efforts.

The U.S. Department of Agriculture plans to begin collecting more detailed data on antibiotics used on farms in a potential precursor to reducing use of such drugs in livestock. The agency is awaiting funding approval for the research. The White House recently issued a sweeping plan to slow antibiotic resistance over the next five years.

(This story corrects first paragraph to specify type of antibiotics)