Aureomycin Content, Bacterial Development, Starter Activity, and Cheese Quality of Milk From Cows Fed an Aureomycin Supplement

It has been reported by Haq et al. (3) and Rusoff and Haq (6) that the milk from cows fed aureomycin in amounts of 130 rag. daily showed normal bacterial development during holding for 12 hours at 35 C. All such milk developed lactic acid and produced a normal acid curd. Presumably, the antibiotics either were not passed into the milk or were present in too low concentrations to affect bacterial development. Similar observations were made by Loosli and Warner (4), who found no aureomycin in milk of cows fed 700 rag. of the antibiotic daily for 10 days. Also, they found that feeding 500 rag. per day for 6 days did not affect cheese starter activity in the milk. Bradfield et al. ( Olson et al. ( Some types of bacteria were suppressed but were compensated for by the growth of other types. A study on the feeding of aureomycin to dairy cows (1) provided an opportunity to investigate further the possible elimination of the antibiotic into the milk. Examinations were made to determine if the milk had an inhibitory effect on bacterial development or if it affected cheese manufacture and quality. Also, the milk was assayed for aureomycin content.