Antibiotic dry-off therapy for intramammary infections in dairy sheep and goats

Abstract Text: Mammary glands are susceptible to new infections especially at the end of lactation and prior to parturition and control of subclinical udder infections is still an issue in small ruminants. Intramammary infections (IMI) during the dry period are likely to remain from the previous lactation to the next or develop during this period which can lead to reducing milk production in the ensuing lactation. Ninety-four lactating dairy ewes (Manchega, 47; Lacaune, 47) and 20 Murciano-Granadina dairy goats were used to evaluate the effectiveness in reducing the prevalence of IMI with a dry-off antibiotic therapy (1 syringe/gland of Mamyzin® containing 100 mg of penethamate hydriodide, 280 mg of benethamine penicillin and 100 mg of framycetin sulphate; Boehringer-Ingelheim, Sant Cugat del Vallès, Spain). At drying-off animals were classified into 3 groups according to the gland bacteria status: 1) N0 (non-infected animals without treatment), T0 (non-infected animals with dry-off therapy) and T1 (infected animals with dry-off therapy). The goat herd was classified into T0 and T1 groups due to the number of available animals. Prevalence of bacterial isolation from milk was determined at the following lactation (15, 40 and 60 DIM in sheep; 20 and 60 DIM in goats). Coagulase negative staphylococci were the most common isolates at dry-off. Incidence of new IMI was determined taking udder halves, previous infection information and results from all samplings after parturition. Rate of new infection was 20 and 18% for N0 and T0 sheep group, respectively. Mammary gland healthy status did not differ between N0 and T0 groups, showing that in this study, dry-off therapy did not protect against new infections in early lactation. Cure rate for the ewes infected and treated at dry-off was 84% after parturition. For goats, the used of antibiotic cured 67% of T1 group while there was no infection found in T0 does. The use of Mamyzin® at dry-off showed to be effective to treat infected glands of sheep and goats, reducing IMI prevalence in the subsequent lactation.

Keywords: dry-off therapy, intramammary infection, dairy ruminants