Relationship between mastitis causative pathogens and somatic cell counts in dairy cows

Abstract

Milk somatic cell count is a key component of national and international regulation for milk quality and an indicator of udder health and of the prevalence of clinical and subclinical mastitis in dairy herds. The objective of this study was to evaluate the presence of mastitis pathogens in milk samples differed by somatic cell count (SCC) in microbiologically positive samples. Also frequency of distribution of samples differed by SCC were studied in non infected samples as well. The milk samples were collected from individual quarters from the dairy farms located in Nitra region with problematic udder health of herd for SCC and bacteriological analysis. Totally, 390 milk samples were examined, and 288 (73.85%) positive milk samples were detected. Four SCC groups of samples (<100, <100<SCC<200, <200<SCC<400 and >400×103/ml) were used to identify presence of microorganisms in positive samples. The most frequently isolated pathogens in samples with high SCC >400×103/ml according to year were Coagulase-negative Staphylococci (29.11 %) in 2012, followed by Staphylococcus aureus (28.0%) in 2010, yeasts (24.05%) in 2012, Escherichia coli (22.78%) in 2012, Bacillus sp. (20%) in 2010 and Pseudomonas aerugenosa (11.88%) in 2011. Coagulase-negative Staphylococci (66.67%) were the predominantly identified in the samples with low SCC <100×103 cells/ml, followed by Bacillus spp (50%), Entrococcus spp. (33.33%) and Staphylococcus aureus (16.67%) and E. coli (16.67%). The results of this study indicated that the SCC of individual milk samples corresponded with the health status of the udder of dairy cows represented by presence of mastitis microorganisms in milk. However, the contamination of milk samples could be also connected with low SCC. On the ohter side the samples with high SCC were found out without presence of microorganism. The further study is needed to identify the reason of high SCC in milk from negative samples.