Use-History of Antibiotics as Related to Their Efficacy in Promoting Growth of Turkeys

A NUMBER of investigators have shown that various antibiotics in the ration of young chicks and/or turkey poults result in improved growth (Almquist and Merritt, 1951; Atkinson and Couch, 1950; Branion and Hill, 1951; Dixon and Thayer, 1951; Heuser and Norris, 1952; Lillie and Bird, 1952; McGinnis et al., 1950, 1951; Runnels et al., 1951; Williams and Hill, 1952). Attempts to improve significantly growth of chicks kept in a “new” environment, not previously occupied by chicks, by the addition of various antibiotics have been unsuccessful (Coates el al., 1951; Gordon, 1952). Bird et al. (1952) showed a chick growth response to aureomycin only after three to four weeks of age in a new environment while the response to the same antibiotic was evident after one week in an old environment, Libby and Schaible (1955) and Waibel et al. (1954) suggested that the continuous use of antibiotics over a long period . . .