Ketosis is a major disease related with negative energy balance and immune suppression in dairy cows. The objective of this study was to examine the differences in β-hydroxybutyrate (BHBA), L-selectin, glucose, tumor necrosis factor-α (TNF-α), non-esterified fatty acids (NEFA), and sialic acid (SA) concentrations in serum in healthy dairy cows and those with subclinical ketosis during the early lactation period. The blood from 20 healthy cows and 20 subclinically affected cows were sampled. All the cows were within the first 2 months of lactation. Serum concentrations of the various aforementioned factors were measured using a number of different methods. The results demonstrated that in cows affected by subclinical ketosis, NEFA concentrations were significantly higher, and glucose and L-selectin concentrations were significantly lower than healthy cows. There was no significant difference in serum SA and TNF-α of dairy cows with subclinical ketosis compared to the control cows. The decrease in concentration of serum L-selectin may be related to immune suppression.

Key words: Immune suppression, L-selectin, Subclinical ketosis, Sialic acid, TNF-a