S. Twelve cows were experimentally infected in two quarters with 1i10% cfu Escherichia coli per quarter and six cows were infused with 500 µg endotoxin into two quarters. Six cows infected intramammarily with Esch. coli were treated intravenously with a bactericidal antibiotic 10 h after infection and subcutaneously 20 h later. Blood and milk samples were collected from all cows at regular time intervals. Milk production decreased more rapidly, but was less pronounced, after endotoxin infusion than during Esch. coli mastitis. The milk production losses in the noninflamed quarters were negligible in endotoxin mastitis, but were substantial during Esch. coli mastitis, probably due to more pronounced systemic effects. Reticulorumen motility was inhibited only during Esch. coli mastitis. Changes in plasma haptoglobin were more pronounced during Esch. coli mastitis, although they occurred sooner during endotoxin mastitis. No changes in plasma activities of enzymes such as lactate dehydrogenase, glutamic-oxaloacetic transaminase and γglutamyl transpeptidase were observed. Concentrations of tumour necrosis factor-α increased in both types of mastitis. Absorption of these cytokines into the circulation was highest during Esch. coli mastitis, especially in the untreated control group. We found only minor differences between the treated and untreated Esch. coli groups, but there were larger differences between the Esch. coli groups and the endotoxin group. These differences were probably due to differences in kinetics, composition and amounts of different cytokines released in the mammary gland and subsequently absorption into the circulation. Endotoxin is probably not directly responsible for the systemic changes during coliform mastitis.

No abstract

S. The respiratory burst activity of polymorphonuclear leucocytes (PMN) was evaluated in eight Holstein cows from 8 weeks before until 6 weeks after calving by chemiluminescence (CL). The CL response started to decrease 1 week before parturition, reaching a minimum during the first 2 weeks after calving. From week 3 of lactation, CL increased again and returned to original levels by week 6 of lactation. Plasma concentrations of 3-hydroxybutyric acid, total bilirubin and bovine pregnancy-associated glycoprotein started to increase before parturition to reach a maximum during the first or second week of lactation. The concentrations of glutamic-oxaloacetic transaminase, lactate dehydrogenase, non-esterified fatty acids and bilirubin increased after calving, reaching a maximum during the second week. A small decrease in plasma cholesterol during the week before and after calving was followed by an increase. The CL response of the PMN showed significant temporal relationships with the plasma concentrations of 3-hydroxybutyric acid, bovine pregnancy-associated glycoprotein, bilirubin, glutamic-oxaloacetic transaminase, non-esterified fatty acids ; that with cholesterol was nearly significant. This means that the change in the CL response with time coincided with the changes in plasma concentrations of these substances with time and that these changes were significantly related with each other. The results of this study show that the decreased respiratory burst activity of bovine PMN around parturition may be related to the extent of the metabolic and hormonal changes. Although the causative relationships are not proven, these results support earlier results suggesting that 3-hydroxybutyric acid and bovine pregnancy-associated glycoprotein may directly affect neutrophil function, whereas non-esterified fatty acids, cholesterol, bilirubin,