Antimicrobial Treatment of Fresh Cows with Subclinical Gram Positive Mastitis

Abstract

Subclinical mastitis is a major contributor to the bulk tank somatic cell count (SCC). Dairies with a moderate to high bulk tank SCC and a low clinical mastitis rate can expect to have a number of cows with subclinical mastitis. Using Dairy Herd Improvement (DHI) SCC results on a regular basis, subclinical mastitis can be identified as the high SCC cows. Identifying the high SCC cows is relatively easy on herds that utilize DHI testing on a regular basis. However, not all high SCC cows need treatment nor is it cost effective to treat all high SCC cows. Antimicrobial treatment should be reserved for those cows that treatment is likely to cure. It is generally regarded that these cows are relatively early in lactation with gram-positive, environmental mastitis (Staphylococcus spp and Streptococcus spp) and have not had chronic episodes of clinical mastitis. This study compared the cure rates of fresh cows with subclinical gram-positive mastitis with and without intramammary antimicrobial treatment.