EFFICACY OF POSTMILKING DISINFECTION WITH BENZYL ALCOHOL VERSUS IODOPHOR IN THE PREVENTION OF NEW INTRAMAMMARY INFECTIONS IN LACTATING COWS

Five Michigan dairy herds participated in a split-herd study to compar e the efficacy of two postmilking teat dips in the prevention of new i ntramammary infections (IMI) in lactating cows. Three hundred seventy cows were assigned to 4% benzyl alcohol, and 387 cows were assigned to 1% iodophor germicidal teat dip. The teat dips were applied by direct ly immersing the teats immediately after milking. Once a group was ass igned to a teat dip, cows in that group maintained on that same teat d ip throughout the trial. Total new IMI numbered 254 and 201 for cows t reated with benzyl alcohol and iodophor germicidal teat dip, respectiv ely. Staphylococcus spp. (52.0%), Staphylococcus aureus (20.1%), and C orynebacterium bovis (12.2%) were the predominant pathogens that cause d new IMI in cows treated with benzyl alcohol. Staphylococcus spp., St aph. aureus, and C. bovis, respectively, were the pathogens responsibl e for 69.7, 12.4, and 4.5% of the new IMI in cows treated with iodopho r. The incidences of new IMI caused by Staph. aureus (0.66 new IMI/100 milking quarters per mo), C. bovis (0.38 new IMI/100 milking quarters per mo), and all pathogens (3.15 new IMI/100 milking quarters per mo) were higher in cows treated with benzyl alcohol than in cows treated with iodophor (0.29, 0.11, and 2.35 new IMI/100 milking quarters per m o, respectively). Incidence of new IMI did not differ between groups f or other pathogens. One percent iodophor prevented new IMI caused by c ontagious pathogens more effectively than did benzyl alcohol.