ChileanJAR

An experiment, designed to show the response of lactating cows to treatments with intramamary antibiotics, to control subclinical mastitis (MSC), was performed at La Platina Research Station (INIA), Santiago, Chile, during 1983. Cows were selected under the following premises: lactation period shorter than 170 days and positive to CMT 2 or CMT 3 and to pathogen bacteria. Three groups, with 25 CMT 2 and 25 CMT 3 quarters each, were establjshed: I, control, without antibiotics; II treated with two intramamary antibiotic applications; and III treated with four applications, both applied in successive milkings. Stafilococcus aureus was the most frequent pathogen, present in 53% of the cases. Only a 38.5% of the quarters CMT 2 and CMT 3 were negative to pathogens presence. There were no significative differences between 2 and 4 antibiotics doses to the udder; both treatments had a significative effect. The proportion of pathogen positive quarters decreased significatively (P < 0.05) in treated cows.