|Sato, Shigeru - NOSAI MIYAGO, JAPAN|
Submitted to: International Animal Agriculture and Food Science Conference
Publication Type: Abstract Only
Publication Acceptance Date: July 26, 2001
Publication Date: N/A
Technical Abstract: We reported that neutrophil function (chemotaxis and myeloperoxidase activity) of cows that would develop retained placenta (RP) was significantly decreased compared to neutrophil function of cows that expelled the placenta normally (No RP) using 142 cows (20 RP, 122 No RP). Why neutrophil function of cows with RP is impaired remains unknown. We hypothesized that the metabolic state of the cow prior to calving influences neutrophil function. Using plasma obtained during the same study, we examined the relationship between energy or calcium status during the periparturient period and the development of RP. An ELISA for interleukin-8 (IL-8), a cytokine critical to neutrophil chemotaxis and activation, was performed on a subset of 8 RP and 8 No RP cows. Plasma calcium and phosphorus concentration decreased at calving in both RP and No RP cows. Energy status at parturition, as assessed by plasma NEFA and beta-hydroxybutyrate concentrations were also essentially the same in both RP and No RP cows. IL-8 concentration at calving in plasma of No RP cows was significantly higher than in RP cows. Fetal cotyledons were collected within 4 h of calving in a subset of 3 RP cows and 15 No RP cows for histologic evaluation. Binucleate giant cells, thought to produce placental lactogen, are reported to be present in "retained" placenta and absent in placenta that are expelled normally. Binucleate giant cells comprised 14.7% of the total epithelial cells in retained placenta and 14% of epithelial cells in placenta expelled normally. We are unable to confirm previous reports suggesting that retention of binucleate giant cells is a cause of RP. We also could not show an association between plasma calcium or energy status at calving and retained placenta.