Mastite subclínica em vacas com diferentes proporções genotípicas Holandês-Gir

Abstract

Mastitis is the pathological alteration that most causes economic losses in milk production in country and world, besides causing risks to public health. Identification of the main etiological agents, which caus mastitis and their association with somatic cell counts (SCC) are essential tools to prevent and control disease in herds. The objective of the present study was to evaluate the occurrence of subclinical mastitis and association between isolated microorganisms and SCC in crossbreed dairy cattle. Information monthly of California Mastitis Test (CMT), bacteriological tests and the SCC from two dairy herds were obtained (herd A: genotype of cows was predominance 1/2 H 1/2 Gyr; herd B: genotype of cows was predominance 3/4 H 1/4 Gyr and 5/8 H 3/8 Gyr), located in the semi-arid region of the State of Alagoas, Brazil. Herd A was the most affected by subclinical mastitis. The main etiologic agents isolated were Staphylococcus sp. (37%), Streptococcus sp. (25%), Enterobacteriaceae (16%) and Corynebacterium sp. (11%). SCC was significantly higher for cows presenting the four quarters infected and for cows with two or more than two microorganisms isolated from healthy ones. Higher SCC values (> 1.000.000) were found in the presence of mixed infection (associations) by Staphylococcus sp., with one or more microorganisms of Micrococcus sp., Enterobacteriaceae, Streptococcus sp. and Corynebacterium sp . genera; in mixed infection with Streptococcus sp. and Corynebacterium sp. and by Enterobacteriaceae and Bacillus sp