Estudo da mastite subclinica em ovelhas da raça Santa Inês e sua influência sobre as características físico-químicas do leite

Abstract

The aim of this work was to accomplish a study of subclinical mastitis in ewes of Santa Inês breed and the influence over the physical-chemical characteristics. It was analyzed 31 flocks totalizing 135 primiparous and multiparous ewes in different lactation stages. It was examined 244 mammary glands before the milking samples was collected to realization of Califórnia Mastitis Testis (CMT), somatic cell direct count (SCC), bacteriological analysis and physicalchemical milk compounds (Dornic acidity, chloride concentration, density, fat and pH ). The main epidemiological characteristics of the herds was marked as well as the genotypic characterization of the 18 S.aureus isolates by the PFGE (pulsed-field gel electhrophoresis). Of the 244 analysed samples by CMT, 172 were negative and 72 positive. It was observed in the CMT positive samples, bacterial growth in 73,61%, whislt in the negative 27,32 with association between CMT and bacterial growth (P<0,05). The SCC mean values related to negative CMT was 1,57 x 105 cells/mL, and the positive samples 1+, 2+ and 3+, respectely, 1,01 x 106 cells/mL, 3,23 x 106 cells/mL and 8,41 x 106 cells/mL. With strong dependency between SCC in relation to the intensity of CMT reaction. The microorganisms isolated were Staphyloccus coagulase negative (65,09%), Staphylococcus aureus (13,21%), Staphylococus hyicus (1,88%), Streptococcus spp.(7,55%), Bacillus spp.(2,83%), Citrobacter freundi (0,94%)i, Pantoea agglomerans (0,94%), Enterobacter cloacae (1,88%), Escherichia coli (0,94%), Burkholderia cepacia (1,88%), Pseudomonas putida (0,94%), Pseudomonas stutzeri (0,94%) e Stenotrophomonas maltophilia (0,94%). In a general manner all isolates were sensitive to the antimicrobians tested. The CMT showed to be a good indicator of subclinical mastitis in this species. With recommendations to collect and to do bacterial isolation of the results 1+ and over. It was verified that the chances of infected glands dettection are higher in SCC results over 1 x 106 cells/mL. In consideration of the different bacterial agents isolated the intramammary infections by coagulase positive Staphylococci and Gram negative bacterias cause more intense alterations in the physical-chemical constituents. It was observed alterations (P<0,05) of the values of the Dornic acidity, chloride concentration, pH and density. Of the 31 analysed flocks 25 (80,65%) had reactive animals to the CMT. 61,97% of the cases were multiparous ewes, 56,34% in females with one lamb and 66,07% had one mammary gland compromised. In the genotypic characterization of the S. aureus strains, three lineages was observed of which LA and LC were the most prevalent ones with 38,9and 50,0%, respectively, with distribution in the flocks where this agent was isolated.