Seasonal variations in serum protein fractions of dairy cows during different physiological phases

The seasonal variations of the level of serum total proteins and their electrophoretic fractions in dairy cows, living in the Mediterranean area, were investigated. During different physiological phases, ten dairy cows were housed in a sheltered pen in Sicily (Italy). Throughout the experimental period, ambient temperature and relative humidity were continuously recorded with a data logger and temperature humidity index values were determined. Blood samples were collected every 30 days for 1 year (12 months). Total proteins were assessed by means of a spectrophotometer and electrophoresis was performed using a semiautomated AGE system. One-way repeated-measures analysis of variance ANOVA was applied to determine the effect of time (physiological phase) during the 12 months of monitoring and P values < 0.05 were considered as statistically significant. Using Cosinor rhythmometry, three rhythmic parameters were determined: mesor (mean level) with the confidence interval (CI) at the 95%, amplitude (half the range of oscillation) and acrophase (Φ, time of peak) with the confidence interval (CI) at 95%. After the application of the Cosinor rhythmometry, α₁-, β- and γ- globulins showed a seasonal rhythmicity. In conclusion, these results shed light on the composition of serum proteins of cows during a 1-year study and allowed us to delineate a serum pattern during physiological conditions.