Opsonic activity in mammary secretion and serum of gilts during the lactation period

Abstract

Opsonic activity was studied in mammary secretion and serum during lactation in four healthy gilts. The opsonic activity was determined as peak chemiluminescence and time to peak chemiluminescence in a luminol enhanced chemiluminescence assay. The peak chemiluminescence was significantly (p < 0.05) higher in mammary secretion around parturition than later in lactation. No changes in the opsonic activity were seen in serum during lactation. Overall, the peak chemiluminescence and time to peak chemiluminescence were significantly higher (p < 0.001) and shorter (p < 0.05) respectively, in serum than in mammary secretion. The present study indicates that the opsonic activity is highest in mammary secretion around parturition but decreases later in lactation, and that this change is confined to the mammary gland.