Milk microbiome as an indicator of subclinical mastitis in goats: risk of false diagnosis

To maintain the rhythm of raw milk production and to prevent the development of clinical mastitis, express tests (Kenotest, Mastitest, etc.) are used to determine the number of somatic cells in goat milk. Ignoring the peculiarities of the lactogenesis mechanism in goats by veterinary personnel leads to a false positive diagnosis of subclinical mastitis. We studied the correlation between the number of somatic cells, the cytological picture and the composition of the microbiota in goat milk. The subject of the study was milk samples from each lobe of the udder of dairy goats of the Nubian and Saanen breeds. We determined the approximate number of somatic cells using Kenotest, studied the cytological composition by microscopy of smears stained according to Romanovsky-Giemsa, identified microorganisms using the classical bacteriological method. We showed that coagulase-negative staphylococci, listeria, rhodococci can be found in small quantities in the healthy mammary gland of goats. No positive correlation was found between the number of somatic cells, inflammatory marker cells, and the species diversity of microorganisms in the milk of the animals studied. Thus, our study demonstrates that extrapolation of the express test assessment scale requires validity for goats, considering apocrine secretion of milk. The results of the study indicated the need to change the gradation of the express test results and demonstrated the prospect of reworking the existing and developing new test systems to expand the diagnostic capabilities of veterinary personnel at goat farms.