Abstract

In the sow, acute coliform mastitis is the major cause of dysgalactia at parturition, a period when normal milk production is paramount for the survival of newborn piglets. Polymorphonuclear leukocytes (PMN) that phagocytose and kill bacteria is the first line of defence by the immune system against E. coli infection in the mammary gland. The overall aim of this thesis was to elucidate this aspect of the sow immune system around parturition in order to gain a better background understanding of the disease. The course of events regarding the number and function of leukocytes in the blood circulation and locally in the mammary gland was described in healthy sows around parturition. At parturition, PMN reached a peak in both blood and mammary secretion. The phagocytic capacity per PMN showed no change, nor did opsonic activity in serum, while the opsonic activity in mammary secretion increased after parturition. The sum effect of the variations on mammary gland defence mechanisms is not clear. The concentrations of oestradiol-17 β and cortisol were determined, and variations were seen in blood and mammary secretion. Directed migration and phagocytosis of PMN in colostrum and milk were compared. Chemoattractant properties of the two types of secretion were similar, while the phagocytic capacity of PMN was lower in colostrum, which may make sows more susceptible to coliform mastitis during the early postparturient period. The concentrations of oestradiol-17 β and cortisol were greater in colostrum. In a study of experimentally induced mastitis, prepartum opsonic activity in serum and functional capacity of PMN in the blood circulation were compared between sows that remained clinically healthy and sows that developed coliform mastitis after intramammary E. coli inoculation at parturition. The pre-inoculation chemotaxis, phagocytosis and expression of CD18 adhesion molecules did not differ between the two groups of sows. In contrast, the pre-inoculation opsonisation of E. coli tended to be better in serum from non-affected sows. Thus specific opsonins likely contribute to local protection of the mammary gland. Possibly, prepartum opsonic activity in serum can be used to predict predisposition to develop clinical mastitis in the peripartal sow. To conclude, no clear-cut evidence for a markedly depressed function of PMN was found in the mammary gland at parturition. No impaired functional capacity of PMN in the circulation was found before parturition in sows that developed mastitis after inoculation. However, the same sows had less opsonic activity for E. coli in serum before inoculation than non-affected sows, which might contribute to a susceptibility to clinical coliform mastitis.

Keywords

sow; mammary gland; leukocyte; neutrophil; granulocyte functions; coliform mastitis; E.coli; parturition; oestradiol-17 β; cortisol; experimental mastitis

Published in

Acta Universitatis Agriculturae Sueciae. Veterinaria
2003, number: 146
ISBN: 91-576-6363-7
Publisher: Swedish University of Agricultural Sciences

SLU Authors

• Österlundh, Ingrid

  • Department of Obstetrics and Gynaecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Clinical Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/117367