FACTORS ASSOCIATED WITH CLINICAL MASTITIS INCIDENCE IN FRENCH DAIRY HERDS DURING LATE-GESTATION AND EARLY LACTATION

A prospective epidemiological survey was conducted in dairy herds in B rittany (France), concerning 139 herd-years. The data were divided int o ten 14 herd-year groups (deciles) and three of these were compared u sing discrimination by barycentric analysis to study herd late gestati on and early lactation variables associated with the annual incidence of herd clinical mastitis in the first 60 days of gestation (CMAI). Th e first decile included herd-years with low CMAI (0 to 4.6 %), the sec ond decile, herd-years with medium CMAI(11.6 to 14.3 %) and the last d ecile, herd-years with high CMAI (26.3 to 45.5 %). Herd data included diet components, milk yield and reproduction parameters, clinical dise ases, body condition score, body dirtiness score and circulating bioch emical and hematological markers. The high CMAI group had the followin g characteristics: 1) lower percentages of dried cows supplemented wit h vitamins 'ADE'; 2) higher levels of plasma ceruloplasmin and higher gamma glutamyl transferase activities (GGT) in the late gestation peri od; 3) higher percentages of winter calvings (December, January, Febru ary). Clinical mastitis risk could be controlled by supplementations w ith vitamins A, D and E in the late gestation period, because of the p otential relationship between oxidative stress and mastitis. Higher GG T activities would be associated with Fasciolasis via common climatic risk factors (rainfall, humidity) for both mastitis and liver flukes. Winter calving and clinical mastitis would be associated with unfavour able hygiene conditions and stress at calving related to high animal d ensity and bad weather conditions. Ceruloplasmin could be a specific p redictor for mastitis risk through nutritional, immune and genetic int errelated factors. (C) Inra/Elsevier, Paris.