Diseases are serious constraints affecting dairy cattle production and these diseases affect livestock production in various ways, such as reduced growth rate, milk production, fertility and value of hides and mortality, thus cause considerable economic losses to livestock keepers. In dairy practice, disorders of the udder are among the most frequent clinical conditions encountered. Hence, this study was planned to estimate the incidence of clinical mastitis among dairy cows in the Cuddalore District of Tamil Nadu. Multistage random sampling technique was used to select the dairy farmers and dairy animals. The selected district comprised 13 blocks of which, four blocks, viz., Parangipettai, Bhuvanagiri, Kammapuram and Virudhachalam were randomly selected. In the next stage, two villages from each selected block were chosen randomly. In total, 1000 farmers having dairy herd size of 2 to 8 were chosen again randomly from the selected blocks, 500 from each block. The study was taken up during the months of April and May, 2009 and the data collected from the sample units related to the year 2008-2009. Clinical mastitis incidence in the study area was found to be ranged from 17.8 per cent in Bhuvanagiri block to 18.4 per cent in Virudhachalam block with overall incidence rate of 18.1 per cent. Chi- square analysis revealed that the incidence of mastitis was independent of block where the dairy animal belonged to.
