ASSOCIATIONS BETWEEN OFF-LABEL FEED ADDITIVES AND FARM SIZE, VETERINARY CONSULTANT USE, AND ANIMAL AGE

Data from the United States National Swine Survey collected by the Nat ional Animal Health Monitoring System were used to describe the use of feed additives in swine feeds, Data were collected from 710 farms. Th e concentration of feed additives expressed in grams per ton of comple te feed was described by stage of production, and the use of feed addi tives above the labeled treatment levels (i.e. off-label) was identifi ed, Of the 3328 feeds, about 79% contained feed additives used in the labeled manner. For all classes of pigs, the prevalence of labeled fee d additive use was greater than 75%. Penicillin was used according to its label most often, followed by apramycin, bacitracin, tetracyclines , lincomycin, and tylosin. Carbadox had the highest prevalence of off- label use. Of the 699 feeds that included feed additives in an off-lab el manner, about 57% included additives at greater than the recommende d concentrations or were fed to an incorrect class of pig. About 56% o f the feeds had off-label combinations of additives. Small farms were more likely to use rations with no feed additives than intermediate or large farms (P < 0.001). Of those farms using feed additives, the odd s of a small farm using all feed additives in the labeled manner was 7 .7 times that of an intermediate or large farm (P < 0.0001). After con trolling for herd size, producers who used a veterinary consultant wer e 2.1 times more likely to use feeds with feed additives (P < 0.0001). (C) 1997 Elsevier Science B.V.