Flow cytometric analysis of somatic cells and oxidant/antioxidant profile in dairy cows with subclinical mastitis

Abstract

Flow cytometric analysis of somatic cells count (SCC) and oxidant/antioxidant status of cows with subclinical mastitis (SCM) were investigated in 75 lactating Holstein-Friesian cows (20 controls; 55 SCM cows). Milk from active quarters (n=280) and blood samples (n=75) were aseptically collected. Milk samples were subjected to California Mastitis Test (CMT), microbiologic examination and flow cytometric analysis. Blood and milk samples were analysed for malondialdehyde (MDA) concentra-tions and total antioxidant capacity (TAC). Microbiological examination revealed 3 major pathogens in a single or mixed infection: Streptococcus species (26.9%), Staphylococcus species (57.7%) and Escherichia coli (49.23%). Flow cytometric analysis showed significant increase (P<0.05) in inflam-matory cells in milk of cows with SCM compared to control cows. Differential SCC was characte¬rised by significant increase (P<0.05) in polymorphonuclear leukocyte (PMNL) counts compared to normal milk. Additionally, Staphylococcus infection alone or mixed with other lactopathogens re-sulted in dramatic increase in PMNL. There was a significant decrease (P<0.01) of TAC in plasma and milk (0.49 ± 0.04, 0.27 ± 0.03 mM/L, respectively) and significantly increased (P<0.01) serum and milk MDA concentrations (13.72 ± 0.3, 7.72 ± 0.17 nmol/mL, respectively) in SCM cows. In conclusion, differential SCC is a reliable index for early detection of SCM. Milk PMNL population can be used as a useful indicator for evaluation of udder infection. Additionally, a combination of MDA and TAC can provide complementary information about the health status of udder in dairy farms.

Keywords

• antioxidant
• flow cytometery
• mastitis
• somatic cell