Reproductive steroids in the bovine. VI. Changes and interrelationships from 0 to 260 days of pregnancy.

Abstract

Summary Urine and blood samples were collected from nine pregnant dairy cows on days 0, 7, 14, 19, 28, 35, 42, 65, 95, 125, 155, 185, 200, 215, 230, 245 and 260 days after breeding. The cows subsequently delivered heathy single offspring. The objectives were to evaluate in- terrelationships between rates of excretion of estrogens in urine and concentrations of pro- gesterone, luteinizing hormone (LH), corti- costerone and cortisol in jugular blood plasma. The first significant change in rate of ex- cretion of urinary estrogens was an increase in estradiol-17a on day 42 as compared to day 35 and day 65. After day 65 rates of excretion of estradiol-17~ (P<.01) and estrone (P< .05) accelerated and were 20-fold and 6-fold higher, respectively, by day 230. Differences in rate of excretion of estradiol-17fl between days were significant (P<.05) and generally but not consistently higher after midpreg- nancy. Levels of plasma LH decreased (P<.01) and progesterone increased (P<.05) from day 0 to day 7. Levels of plasma LH did not change after day 7 and the corticoids did not increase significantly (P<.25) from 0 to 260 days of pregnancy. Plasma progester- one increased (P<.01) from day 7 (9 ng/ml) to day 42 (20 ng/ml), decreased from day 42 to day 125 (10 ng/ml; P<.01) and then gen- erally increased to the maximum average level (26 ng/ml) on day 245 (P<.01) before de- creasing to 14 ng/ml on day 260 (P<.01). Partial regressions, derived by multiple re- gression analysis including the hormones and days as independent variables were used to define hormone interrelationships. Plasma pro- gesterone was positively related (P<.05) to urinary estradiol-17p from 7 to 42 days and was negatively related (P<.10) to LH from 42 to 260 days. The partial regressions for estradiol-17~ (positive) and estrone (nega- tive) were significant (P<.01) during 7 to 260 days of gestation when plasma cortisol was the dependent variable. Literature Cited Amoroso, E. C. I952. Placentation. In A. S. Parkes (Ed.). Marshall's Physiology of Reproduction. Vol. II. Longman, Green, London. Biomedical Computer Programs. 1964. W. J. Dixon (Ed.). Health Sciences Computing Facility, De- partment of Preventive Medicine and Public Health, School of Medicine, University of Cali- fornia, Los Angeles. Bowerman, A. M., L. L. Anderson and R. M. Mel- ampy. 1964. Urinary estrogens in cycling, pregnant, ovariectomized and hysterectomized gilts. Iowa State J. Sci. 38:437. Edgerton, L. A. and R. E. Erb. 1971a. Metabolites of orogesterone and estrogen in domestic sow urine. I. Effect of pregnancy. J. Anita. Sci. 32:515. Edgerton, L. A. and R. E. Erb. 1971b. Metabolites of progesterone and estrogen in domestic sow urine. II. Changes pre- and postpartum and effect of feeding 6 methyl-17-acetoxy-progesterone. J. Anim. Sci. 32:930. Erb, R. E., V. L. Estergreen, Jr., W. R. Gomes, E. D. Plotka and O. L. Frost. 1968a. Progestin levels in corpora htea and progesterone in ovarian venous Downloaded from jas.fass.org