P-155: Pattern of Serum Adiponectin Concentrations in Normal Estrous Cycles of Postpartum High-Producing Dairy Cows

Background: There are accumulating evidences showing the role of adiponectin, a newly discovered adipocytokine secreted from adipose tissue, in the regulation of the ovarian function in dairy cows. The objective of the present study was to evaluate the pattern of serum adiponectin concentration during a normal estrous cycle in the postpartum dairy cows. Materials and Methods: Coccygeal vein blood samples were collected from 71 high producing dairy cows, with a history of being clinically healthy, twice weekly (three days apart) from the 1st to 7th week postpartum. Serum progesterone (P4) concentrations were determined twice weekly using a validated commercial radioimmunoassay kit (Immunotech kit, France). Based on the progesterone profile, a subset of cows (n=6) with a pattern of normal luteal activity was randomly selected. Serum adiponectin was determined twice weekly using a validated commercial ELISA kit. Changes in mean serum adiponectin concentrations were analyzed using paired sample t test (SPSS 11.5, p<0.05). Results: Serum adiponectin concentration gradually decreased (p<0.05) while the serum progesterone concentration increased after ovulation by day 17 of cycle. During the periovulatory period, adiponectin concentration were in maximum levels, when the P4 was in minimum concentration; but when the level of P4 reached to the highest level during the estrous cycle, serum adiponectin concentration was in its nadir. Conclusion: During a normal estrous cycle in highproducing dairy cows with normal luteal activity, the fall in serum adiponectin concentrations was accompanied by a marked increase in progesterone concentrations. Inspection of the adiponectin profile suggests that this increase was initiated a few days before next ovulation.