Selective treatment: Improving the safety and milk quality on dairy goat farms

This study aimed to evaluate the selective antibiotic therapy at dry-off to reduce the prevalence of IMI in dairy goats. Two dairy goat farms (farm 1 from Ohio with 178 does and farm 2 from South Dakota with 80 does) were enrolled in this study. Both farms use automatic milking and apply similar procedures for udder preparation (pre-dipping, wipe dry with a single-service paper towel, and post-dipping). Following cleaning, the teats were disinfected with 70% ethanol and dried with disposable paper towels. Udder-half milk samples were taken for bac- terial culturing and SCC after first squirts were discarded, and 3 to 4 mL samples were collected into sterile tubes. Phase 0 was the baseline time before the trial started, and farmers used dry-off blanket therapy. The prevalence of bacterial isolation from the milk was determined in the subsequent lactation at dry-off (phase 1), where the bacteriological status of all quarters at dry-off was determined to assess the effective- ness of the practice later. Phase 1 prevalence of IMI was 23% (55/241) for farm 1 and 28% (28/101) for farm 2. The decision to use selective antimicrobial treatment at dry-off was based on culture – only culture- positive does receive treatment. Non-Staphylococcus aureus were the most common isolates for both farms. In the subsequent dry-off period (phase 2), based on bacteriological culture, the prevalence reduced to 16% (40/256) for farm 1 and 17% (13/75) for farm 2. The cost of treatment, calculated by farmers, was estimated to be on phase 0 equal to US$1,070, phase 1 equal to US$260, and phase 2 equal to US$166 without considering labor costs related to the antimicrobial usage. Milk quality also improved as the absolute difference between average SCC values from phase 1 to the average SCC values in phase 2 decrease in 893x103 cells/mL for farm 1 and around 1,582x103 cells/mL for farm 2. This preliminary report indicates that bacteriological culture could be a good strategy to reduce the cost and use of antibiotics while enhancing mammary health in dairy goats’ farms