Antibiotics in Dairy Cattle Nutrition. III. Effects of Different Levels of Aureomycin Intake upon the Growth and Well-Being of Dairy Calves, and the Association of Differences with Changes in Environment

Between November 1950 and May 1952 several workers (1) reported that the feeding of aureomycin to young calves exerts a favorable influence on their growth and well-being.Later reports also have indicated that aureomycin feeding favorably influences calf growth (2, 5, 6, 8, 9, .11,12, 13, 14, 16, 18) and reduces the incidence of scours (12).In an earlier experiment conducted at the Kansas Station (1) the calves were raised in a barn used for this purpose for 18 years and in which the incidence of scours and colds and associated death losses had been considered extremely high.Under these unfavorable conditions, aureomycin feeding to 12 weeks of age resulted in a 43% gain in weight and markedly reduced the incidence of scours and colds.The experiment reported herein was initiated to determine what beneficial effect, if any, aureomycin would have on calves raised under more favorable conditions.Also, in order to obtain more information on the importance of the amount of aureomycin fed, two levels were compared in this study. EXPERIMENTAL PROCEDUREThirty Holstein and Jersey calves were divided randomly by breed and sex into three groups.Every group contained three females and two males of each breed.Calves in one group (controls) received a basal ration only.Calves in the second group received, in addition to the basal ration, Lederle's Aurofac in amounts calculated to supply 15 mg. of aureomycin daily for each 10'0 lb. of calf weight.Calves in the third group were fed like those in the second group except that the level of aureomycin was increased to 45 mg.Aurofac was ingested once daily by capsule for the first 16 weeks and thereafter added once daily to the grain ration.The calves were started on experiment when 4 days old and were kept on experiment until 25 weeks of age.The majority of calves was from the Kansas State College dairy herd.A few were borrowed from a breeder of purebred Jerseys.These calves were brought to the College after they had been with their dams for 3 days.