Levels of Luteinizing Hormone in Sera of Ewes near the Time of Estrus as Determined by Radioimmunoassay1
- 1 January 1972
- journal article
- Published by Oxford University Press (OUP) in Journal of Animal Science
- Vol. 34 (1) , 88-92
- https://doi.org/10.2527/jas1972.34188x
Abstract
Serum LH levels were measured by radioimmunoassay in ewes treated with progesterone-dimethylpolysiloxane implants. During the early anestrous season (March) the LH surge occurred 42 hr. to more than 68 hr. after removal of the implant. Behavioral estrus was detected 2 to 12 hr. before the LH peak. The typical peak commenced 48 to 50 hr. after implant removal or 8 hr. after onset of estrus. LH rose within a 2-hr, period to levels in excess of 100 ng/ml of serum where they remained for 2 to A hours. Within 8 hr. after the start of the peak, levels of LH in serum had returned to base line. During the estrous season the LH peak began 34 hr. after removal of the implants and estrus was detected 8 hr. after the LH peak. PMS treatment did not significantly affect the time of the LH peak. Increasing the progesterone dosage appeared to increase the interval from removal of the implants to detection of the LH peak. PMS injection at implant removal in ewes with the higher progesterone dosage may have shortened the interval from removal of the implant to the LH peak. The LH peak was not detected in ewes treated with three implants and injected with 500 IU HCG 32 hr. after implant removal. Copyright © 1972. American Society of Animal Science. Copyright 1972 by American Society of Animal ScienceKeywords
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