Concentrations of progesterone, estrogen, and prolactin in plasma were compared among lactations induced in 29 cows by daily subcutaneous injections of .25 mg progesterone and .1 mg estradiol-17beta per kg body weight for 7 days. Superior, median, and inferior lactations were identified by ranking both weightage adjusted maximum milk yields in 7 consecutive days (average 144 +/- 9 kg) and days for milk yield to increase from 5 to 10 kg/day (15 +/- 3 days). Superior and inferior of the former averaged 189 and 101 kg, and their latter averaged 2 and 42 days. Plasma hormones were measured on day 0 before first treatment (day 1), and on days 7, 14, 17, 21, 24, 28, and 35. Superior lactations were associated with below-average progesterone and estrogen in plasma on day 0, rapid decreases in progesterone after day 7 and in estrogen after day 14, and increased prolactin after 7. In comparison, median lactations were associated with elevated progesterone and estrogen after day 17, but prolactin was similar to that of superior lactations. Inferior lactations were associated with decreased prolactin in plasma from days 21 to 35. We hypothesized that (a) first treatment should start 3 to 8 days after estrus, (b) daily doses of estradiol-17beta should be decreased with progesterone unchanged for the 7 days, and (c) estradiol-17beta alone should be continued for 7 days to improve hormonally induced lactations.

Animals↗

PubMed1975

Equine granulosa cell tumors.

Unilateral ovariectomy was performed on 3 mares affected with granulosa cell tumors. Tumor fluid in each mare was found to contain estrogen, testosterone, and progesterone. In 2 mares, preoperative blood plasma concentrations of these hormones were comparable to those of a series of clinically normal mares. The other mare, which had a history of aggressive, masculine behavior, had higher testosterone content in the tumor fluid and in the preoperative blood sample. After surgical removal of the tumors, each mare developed follicles and ovulated with the remaining ovary. Each was eventually bred and 2 conceived. The probability of metastasis of these tumors in mares appears uncertain. Data from other species suggests a guarded long-term prognosis may be justified.

Animals↗

PubMed1975

Induction of parturition in dairy cattle with dexamethasone and estradiol benzoate.

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Adrenal Cortex Hormones↗

PubMed1975

Relationships between immunoreactive estrone and estradiol in milk, blood, and urine of dairy cows.

Quantities of immunoreactive estrone and estradiol in blood plasma, urine, and milk were measured during the estrous cycle and pregnancy of cows. The objectives were to develop a radioimmunoassay procedure for quantifying estrogen in milk and urine and to compare changes in milk estrogen with those in blood plasma and urine. Concentrations of estrone and estradiol in milk varied during the estrous cycle. Relative concentrations of estradiol in blood plasma and milk were not different, but average estrone concentrations in milk were four times greater than those in blood plasma. Concentration of total estrogen (estradiol plus estrone) exceeded 1 ng/ml in colostrum and milk from cows milked prepartum, and was correlated with total estrogen in blood plasma and urine before and after calving. Blood plasma estrone was correlated only with milk estrone whereas blood plasma estradiol was correlated with urinary estradiol, milk estrone, and milk estradiol during the estrous cycle. These results raise possibilities that mammary gland of the lactating cow may concentrate preferentially estrone or convert estradiol to estrone. However, estimated excretion of estrogen through the milk represents no more than a fraction of 1% of the total excreted during the estrous cycle, and the proportion becomes less as gestation progresses up to at least 7 mo.

Animals↗

PubMed1975

Characterization of metabolites in domestic sow urine after intravenous administration of radioactive estrogen and corticosteroids.

We measured distribution of radioactivity among urinary metabolites excreted in nonpregnant and ovariectomized sows after intravenous injection of radionuclides (14carbon) labeled estrone, estradiol-17beta, cortisol, and corticosterone. Treatment with an enzyme preparation (Glusulase) containing both beta-glucuronidase and sulfatase activity, rendered extractable over 95% of the radioactivity recovered from urine with diethyl ether (estrogens) and ethyl acetate (corticoids). Only an additional 1 to 4% of the radioactivity was extracted following solvolysis of the aqueous residue remaining after enzyme hydrolysis and extraction. Radioactivity in nonpregnant sow urine was predominantly in the estrone fraction following injection of either estrone or estradiol-17beta. Moreover, the principal metabolite was estrone monoglucuronide. Only traces of estradiol-17beta and an estriol-like compound were detected. Two other isolates contained radioactivity. One compound probably was 2-methoxyestrone, but structure of the other compound (X1) could not be established. The principal urinary metabolites from injection of cortisol corresponded to chromatographic properties of tetrahydrocortisol and tetrahydrocortisone. Both metabolites were low in urine following injection of corticosterone. The major urinary metabolites from corticosterone injection corresponded to chromatographic properties of tetrahydrocorticosterone and corticosterone. Considerable radioactivity from injection of both corticoids was isolated in the cortol, cortolone, and 11-ketoetiocholanolone - 11beta-hydroxyetiocholanolone areas of chromatograms. The data for corticoids agree with similar data for the human being and cow.

11-Hydroxycorticosteroids↗

PubMed1975

Environmental and lactational variables affecting prolactin concentrations in bovine milk.

Relationships were examined between prolactin concentrations in bovine milk and various environmental and lactational variables. Prolactin was quantified by radioimmunoassay in 1.316 milk samples from two experiments. Environmental temperatures preceding milking, stage of lactation, daily miik yield, and dominance rank of the cow were correlated significantly with milk prolactin concentration. Stepwise multiple regression analysis was used to determine, in order of importance, the variables having significant independent effects on milk prolactin. Ambient temperature extremes, high and low, exerted the greatest effects and were each associated with elevated concentrations of prolactin. In Experiment I,conducted throughout the year, the variable representing maximum temperature preceding milking accounted for 14.3% of the variation in milk prolactin. In Experiment II, conducted during late fall and early winter, the minimum temperature preceding milking accounted for 21.1% of the variation. Although earlier stages of lactation and larger daily milk yields were associated with higher prolactin concentrations, inclusion of lactation stage in the stepwise regression model tended to eliminate almost all the variance of prolactinpreviously associated with daily yield. Dominance measurements indicated that more submissive cows had higher milk prolactin. Individual cows tended to have characteristic prolactin, but this tendency was eliminated by statistical adjustment of the data for environmental and lactational variables.

Animals↗

PubMed1974