Willett LB, Smith KL, Schanbacher FL. Hormone induced lactation in the bovine III. Dynamics of injected and endogenous hormones.
J Dairy Sci 1976;
59:504-14. [PMID:
1262570 DOI:
10.3168/jds.s0022-0302(76)84232-4]
[Citation(s) in RCA: 21] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Three lactations were induced in two cows in two trials by twice daily subcutaneous injections for seven days. Each injection contained .05 mg/kg body weight of estradiol-17beta and .125 mg/kg body weight of progesterone. Included with the hormones in trial 1 was a combination of 233 muCi of [6,7-hydrogen-3] estradiol-17beta and 12 muCi of [4-carbon-14] progesterone. During trial 2,2050 muCi of [2,4,6,7 hydrogen-3] estradiol-17beta were incorporated with the hormones for one cow and 2344 muCi of [1,2,6,7 hydrogen-3] progesterone for the other. Radioactivity from hydrogen-3 and carbon-14 was detected in urine and feces but not in mammary secretion during trial 1. Isotope recovery from [hydrogen-3] estradiol-17beta was too low to quantify. By day 17, 90% of the carbon-14 from progesterone was accumulated in feces and 8.0% in urine. For trial 2, recoveries of radioactivity by day 28 from urine, feces, and mammary secretions were, respectively, 32.4, 56.2, and less than .002% from [hydrogen-3] estradiol-17beta and 6.0, 87.7, and .25% from [hydrogen-3] progesterone. Estrogen and progesterone in plasma averaged 1.83 and 2.61 ng/ml during days 2 to 7. Estrogen decreased more rapidly than progesterone post-treatment, but both had decreased by days 16 to 19 when average prolactin of plasma increased. Quantitative measures of estradiol 17-beta and progesterone absorption, whether in plasma or excreta, were correlated.
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