The objective of the present study was to investigate the microbiological content of cows’ milk in Latvia’s organic farms with a purpose to detect potential microbiological threats in milk. Samples were collected in December 2011 at 12 biological dairy farms of Latvia. Raw milk samples (N=155) obtained from cow composite milk were studied. The total mesophilic aerobic and facultative anaerobic microorganisms (MAFAM), the presence of coliforms and coagulase-positive staphylococci, count of yeasts and moulds were analysed using standard methods. Of the sampled cows 50% had a low somatic cell count (SCC) (LESS THAN 200,000 cells mLE-1), 23% - high, but 27% had a very high SCC (greater than 500,000 cells mLE-1). The mean value of MAFAM in the samples with low, high and very high SCC was 4.7, 5.0 and 5.0 log10 colony forming units (cfu) mLE-1, respectively. The yeasts were present in 57% of milk samples with the mean concentration of 3.1 log10 cfu mLE-1. Moulds were found in 27% of all milk samples; their mean concentration was 4.4 log10 cfu mLE-1. Identified mould strains belonged to genera Absidia, Aspergillus, Geotrichum, Mucor and Penicillium. In cases of subclinical mastitis and latent mammary infection the most distributed mastitis pathogens were Staphylococcus aureus, Micrococcus kristinae, Bacillus cereus and coagulase negative staphylococci.

Milk quality analyses were carried out at the Department of Veterinary Medicine of the LUA Research Centre "Sigra". The total amount of investigated samples was 140, of which 81.4% proved to be appropriate for extra and first class milk, but 18.6% were unqualitative. The total number of microorganisms ranged from 8000 to 20,000,000, but the number of somatic cells from 1000 to 4,068,000 in 1 ml of milk. Coagulase - positive Staphylococcus aureus were isolated in 8 cases or 5.7%. Coagulase - negative Staphylococcus were isolated in 31 cases or 22.1%. Using the BBL Crystal Indentification System for Gram-Positive microorganisms, four species of microorganisms Staphylococcus aureus, Staphylococcus intermedius, Micrococcus sedentarius and Micrococcus luteus were identified which are building various colonies on Baird-Parker Agar.

Udder secretion samples from mastitic and healthy udders were examined at the Department of Veterinary Medicine of the LUA Research Centre "Sigra". In total, 117 samples from 117 cows were investigated. Somatic cell count was recorded for cows with clinical and subclinical infections, and uninfected cows. The mean somatic cell counts for cows with clinical and subclinical mastitis were 1 825 250+-417 697 cells ml*[-1) and 967 866+-75 796 cells ml*[-1), respectively. For healthy cows the mean somatic cell count was 87 666+-15 384 cells ml*[-1). Gram-positive microorganisms from the genera Micrococcus, Staphylococcus, Streptococcus, and Corynebacterium, and gram-negative microorganisms from the genera Enterobacter, Klebsiella, Salmonella, Escheria and Pseudomonas were isolated from samples from mastitic quarters.