The feeding of antibiotics in small doses to entire herds or flocks to promote rapid weight gain poses a serious threat to human health. The constant dosing promotes the emergence of germs that are resistant to veterinary drugs and to the very similar drugs used in humans. That raises the risk that when humans are infected by the germs, the medicines they rely on will be less effective. Earlier this month, a federal magistrate judge in New York told the Food and Drug Administration to quit dillydallying on its three-decade effort to curb indiscriminate use of antibiotics in farm animals to spur their growth. He set a timetable for the agency to follow in withdrawing two important drugs - penicillin and two forms of tetracycline - from widespread use in animals. The trouble is, that timetable will give the F.D.A. five more years to complete the process.