A well-functioning immune system is the basis for protection against infectious and metabolic diseases, and a smooth return to homeostasis. The periparturient period is considered critical because major changes in the endocrine, behavioural, digestive, and immune systems dysregulate immune function, leading to immunosuppression. With age, the immune system could become dysregulated. The purpose of the present investigation was to compare changes in plasma concentrations of acute phase proteins, cortisol, and haematological parameters in the peripheral blood of two age-related groups of healthy ewes to get a better understanding of changes around lambing. Two groups of ewes were enrolled in the study: 3-year-old (young; n = 9) and 7-year-old ewes (old; n = 9). All females were synchronised and inseminated. In blood plasma, serum amyloid A (SAA) and cortisol concentrations were measured using ELISA tests, a spectrophotometric method to determine haptoglobin (Hp), and a thrombin clottable estimation to determine the fibrinogen (Fb) concentration. The blood parameters were examined using an automated haematological analyser. In clinically healthy ewes, no significant effect of age was observed in SAA, Hp, Fb and cortisol concentration in most of analysed terms. SAA, Hp, Fb, and cortisol fluctuations typical for the periparturient period were observed. There were no age-associated differences in red or white blood cell parameters.
Keywords: acute phase proteins; age; cortisol; ewes; haematological parameters.