Prevalence of subclinical mastitis and influence of breed, parity, stage of lactation and mammary bacteriological status on Coulter Counter Counts and California Mastitis Test in the milk of Saanen and autochthonous Greek goats

Abstract

Coulter Counter Counting (CCC), California Mastitis Test (CMT) and bacteriological examination were performed on milk samples from healthy primiparous Saanen, multiparous Saanen (SA) and multiparous autochthonous Greek (AG) goats, in six flocks in northern Greece. Mean CCC in bacteriologically negative milk samples were higher ( P < 0.05) in AG goats than in multiparous SA, and in multiparous than in primiparous SA, throughout the lactation period. No differences were noticed with regard to the mean CCC in bacteriologically negative milk samples of primiparous SA, multiparous SA and multiparous AG goats from Day 50 up to Day 110 after kidding. Mean CCC in the milk of multiparous goats increased ( P < 0.001) from Day 125 in AG goats and from Day 170 in SA goats up to Day 185 after kidding. Parity, breed and stage of lactation differences were not noticed with regard to the mean CMT scores. Prevalence of bacteria in the milk samples ranged between the flocks from 19.0% to 35.7% of the glands. The proportion of bacteriologically positive samples was higher ( P < 0.05) in multiparous than in primiparous SA goats whereas no differences were noticed between multiparous SA and AG goats. Prevalence of coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus spp. and other bacteria varied between the flocks. No breed or parity differences were observed with regard to the type of bacteria isolated. The presence of bacteria in caprine milk elevated both CCC and CMT scores in primiparous SA, multiparous SA and multiparous AG goats. This elevation was associated with the type of bacteria; S. aureus elevated CCC and CMT scores in milk more than coagulase-negative staphylococci did. The results of the present investigation lead to the conclusion that Coulter Counter and CMT could be appropriate only for the prediction of the presence of a major pathogen such as S. aureus in goat's milk, even if we try to restrict their application to only one breed, to one parity or to a specific stage of lactation.