The recalled products were produced Aug. 23, 24, 30, and 31 of 2011, and are marked with the establishment number “P-963.” A study from Ankara University used a conventional culture technique to isolate "salmonella" to determine the seasonal effects on incidence rates in ground turkey. In spring, summer, and autumn, "salmonella" rates are highest (48%, 55%, and 63% respectively). During the winter season the frequency of "salmonella" significantly lowers to 16%. Due to the complexity of food processing, "salmonella" found in processed turkey does not necessarily stem from the product itself. Before customers get the product, it goes through a series of phases including "flock, slaughterhouse, processing, distribution centers and retail marketing. The conditions of each of these environments influence whether or not the ground turkey becomes contaminated. Certain strains of "salmonella" in ground turkey resist antibiotics. Ankara University's study found "salmonella" in ground turkey resisted 25% of nalidixic acid, 17% of streptomycin, and 15% of tetracycline. Overall, approximately one out of ten of the samples had "salmonella" strains that were resistant to four or more antibiotics.