SEQUENTIAL CHANGES IN PLASMA PROGESTERONE IN THE COW DURING THE ESTROUS CYCLE, PREGNANCY, AT PARTURITION, AND POST-PARTUM

• DOI: 10.4141/cjas72-076
• Publication Date: 2010-03-15T16:33:13Z
• Authors: H. A. ROBERTSON
• Keywords: Post partum; Basal (medicine)

The progesterone concentration in peripheral plasma has been measured sequentially individual cows during the estrous cycle, gestation, at parturition, and post-partum. During cycle was lowest just before, during, after estrus when level (0.1–0.4 ng/ml) similar to that found three ovariectomized cows. commenced rise on 4th–6th day (day of = 1st day), reached a peak 3–6 ng/ml 11th–13th day, dropped rapidly over 24–48-hr period basal value 24–72 hr before next estrus. In early pregnancy, maximum levels luteal phase cycle. Between 90 150 days there an indication decline relatively low followed by variable rise. Prior gradual 35–70 reaching <2.0 parturition. Following remained <0.5 until first sign resumption cyclic activity. time for this occur very (20–>60 days). Although not conclusive, evidence favors view behavior occur, must be preceded discharge mucus can without previous