The heads of two Iowa egg farms, linked to that massive salmonella outbreak this summer, testified before a House committee on Capitol Hill Wednesday.

Austin "Jack" DeCoster, the owner of Wright Country Egg, said he was "horrified" to learn his eggs may have caused as many as 1,600 people to become sick.

He also said the outbreak might not be the company's fault, suggesting an outside supplier may be to blame.

An FDA investigation found towers of manure and bug and rodent infestations at the farms.

Another investigation found one of the companies had received hundreds of positive results for salmonella in the two years before the outbreak.

Rep. Bart Stupak, D-Mich., the House committee chairman, said the outbreak shows "a very disturbing picture of egg production in America."

One of the victims who contracted salmonella was 30-year-old Sarah Lewis.

She testified that she had a fever and diarrhea after eating a custard tart at her sister's graduation. Lewis' sister also became sick from salmonella poisoning.

"Knowing how sick we were scares the heck out of us now," Lewis said.

Wright Country Egg and Hillandale Farms together recalled more than half a billion eggs.

The federal Centers for Disease Control and Prevention said this summer's salmonella outbreak was the largest of its kind since the agency began keeping records in the late 1970s.

No one has reported any deaths due to the salmonella outbreak.

The FDA is still investigating the specific cause.