IgG and IgM levels in dairy cows during the periparturient period.

In dairy cows, the incidence of infectious diseases during the periparturient period is high. The most common diseases ante partum (a.p.) and post partum (p.p.) are mastitis and puerperal toxicaemia, puerperal septicaemia, and chronic endometritis, respectively. Studies suggest that this is related to an immunosuppressed status during this period. Therefore, the aim of this study was to determine the periparturient immune status characterized by concentrations of IgG and IgM in peripheral blood and colostrum samples of dairy cows and to assess in detail whether variations in immunoglobulin levels may be related to age and status of productivity. In addition, a possible correlation between the course of immunoglobulin levels and lymphocyte concentrations was assessed. Eighteen clinically healthy German Holstein and Red Holstein dams were selected for this study and sampled regularly between the 8(th) week a.p. and the 4(th) week p.p. IgG and IgM levels were determined using two novel competitive ELISAs. Results demonstrated a dramatic decrease of serum IgG and IgM levels beginning at the 8(th) week and 4(th) week a.p., respectively, both reaching trough at parturition. The IgG level recovered by the 4(th) week p.p., while IgM concentrations remained low. The extent of IgG reduction seemed to be dependent on the initial IgG concentration when the cow was dried-off (8(th) week a.p.). In contrast to IgM, the degree of IgG reduction correlated significantly with the IgG concentrations in the colostrum. Furthermore, a cross-correlation between the IgG levels and the lymphocyte counts was detectable (P < 0.01). In conclusion, the antepartal decline of blood IgG and IgM levels as well as the low periparturient IgG levels could reflect a "physiological phenomenon" of dairy cattle. If the phenomenon is associated with an unstable immune system, it must be assessed in future studies. Nonetheless, a sensitive immune system could explain the high incidence for infectious diseases during this period.