Nonantibiotic approach in control of bovine mastitis during dry period.

Twenty cows were used to determine effectiveness of a nonantibiotic method for control of intramammary infection during the dry period. Right mammary quarters of cows were infused with colchicine, endotoxin, or both at 1 day prior to or at the end of lactation. Left quarters were uninfused controls within group. Samples (n = 1105) of foremilk were obtained aseptically from quarters for bacteriological analysis. Quarters were sampled during the last week of lactation, early nonlactating period, prepartum, at parturition, and 1 and 2 wk postpartum. Primary pathogens isolated were esculin + streptococci, coagulase + staphylococci, and coliform bacteria. Isolation of primary pathogens was reduced 50% in right infused quarters during the 1st wk of involution as compared to left uninfused quarters. Thirteen of 80 quarters were infected at the end of lactation (6 right and 7 left), and 20 of 80 quarters (9 right and 11 left) were infected at calving. Sixteen of the 20 infections at calving were new during the dry period. Treatment reduced infection during early involution but failed to prevent new infection during the remainder of the dry period.