Serum cholesterol and triglycerides in postpartum beef cows and their relationship to the resumption of ovulation

The variations in lipid metabolism according to the physiological stage and their relationship to the resumption of postpartum ovarian cyclicity were assessed in Limousine beef cows fed a grass diet over 3 yr. Weekly blood sa mples were collected from 59 cows beginning 10 wk before to 20 wk after cal ving to evaluate serum cholesterol and triglyceride concentrations and elec trophoretic lipoprotein fractions. After parturition, progesterone concentr ations were also measured at weekly intervals to determine time of resumpti on of ovulation. Cows were categorized by resumption of postpartum ovarian cyclicity into 3 groups: early (4 to 6 wk post partum, n=36); mid (7 to 10 wk post partum, n=46) and late (after 11 wk post partum, n=38). Higher seru m triglyceride values (P<0.05) were observed during the last 10 wk of pregn ancy (0.36 +/- 0.15 g/L) than during the first 20 wk of suckling (0.29 +/- 0.09 g/L). Cholesterol values decreased significantly (P<0.05) at the end o f pregnancy, were minimal (1.01 +/- 0.03 gn) at parturition, and increased again up to 9 wk post calving. Increased cholesterolemia and low serum trig lyceride values after calving could be linked to the increased bovine a-lip oprotein fraction and decreased beta fraction. Serum triglyceride concentra tions were not related to the resumption of postpartum ovarian cyclicity. H igher serum cholesterol values were observed from 2 wk before to 4 wk after calving in cows with early rather than mid and late resumption of ovarian cyclicity. Therefore, modifications in lipid metabolism during the puerperi um seem to be related to resumption of cyclicity during the early postpartu m period. (C) 1999 by Elsevier Science Inc.