HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Baker, L. N. Articles by Casida, L. E. Search for Related Content PubMed Articles by Baker, L. N. Articles by Casida, L. E.

Inhibition of Heat by Progesterone and Its Effect on Subsequent Fertility in Gilts^{1, 2}

University of Wisconsin

Abstract

Ninety-five gilts of mixed breeding were used in three trials to test their response to injections of crystalline progesterone (levels of 25 and 100 mg. daily started on day-10 or -15 of the estrous cycle and continued through day-28) with the objectives being (1) to develop a treatment which would inhibit heat and ovulation and would be followed by a fertile heat, and (2) to observe the effects of incomplete ovulation on fertility.

Heat was inhibited by progesterone on both dosages and at both times of onset of injections. However, the fertility of the heats following these injections was nil in those gilts on the 25 mg. dose and low for those on the 100 mg. level with injections begun on day-15.

The latter showed the following results: Heat was inhibited in all gilts during treatment. The heat period subsequent to treatment (shown by 34 of 36 gilts) was shortened by an average of 0.3 days. The average number of cysts in the 18, 3-day gilts, observed following treatment, was increased by 6.5 over the controls. Four of these 18 gilts had only cysts. The average number of fertilized ova was decreased by 5.5 ova (reflecting ovulation decrease, ova loss and fertilization failure). Embryonic death was not materially altered by the progesterone treatment.

Those control and experimental gilts which had ovulated were divided into cystic and non-cystic subgroups. It was then found that progesterone increased the ovulation rate over all experimentals by 3.2 ova. There was a much greater increase in number of lost ova in the cystic gilts over the non-cystics, both receiving progesterone, than in similarly classed gilts not receiving progesterone. Fertilization failure was significantly increased over all progesterone groups but was not affected by the cystic condition.

¹ Paper from the Department of Genetics (No.543) and Department of Animal Husbandry.Published with the approval of the Director of the Agricultural Experiment Station.

² The authors wish to acknowledge the assistance of W. G. Black in the conduct of trial I, and of L. P. Brunker and B. P. Haasl for their assistance throughout the experiment.

³ Present address:—Department of Animal Husbandry, Mississippi State College, State College, Mississippi.