Submission Number: JAM-4-27-3

Abstract Number: 211

OVIDUCTAL PROTEIN AND OVARIAN STEROID HORMONE CONCENTRATIONS DURING THE PUBERTAL TRANSITION IN EWES.

James Berardinelli* and Ron Adair

Department of Animal and Range Sciences, Montana State University, Bozeman, MT, USA. ¹

Abstract:
The purpose of this study was to evaluate changes in oviductal protein and ovarian steroid hormone concentrations in ewe lambs during the first five days of the pubertal estrous cycle (FE), third estrous cycle (TE), or an estrous cycle of mature ewes (ME). At puberty (first estrus), ewe lambs were assigned to be bi-laterally salpingectomized during their first or third estrous cycle on either Days 0 (estrus), 1, 2, 3, or 4. ME ewes were assigned at estrus to day of surgery. Jugular blood samples were taken from each ewe on each surgery day. Samples were assayed for estradiol (E2) and progesterone (P4). Ampullae (AMP) and isthmi (IST) of each oviduct were weighed and flushed twice with 3 and 1.5 ml Delbecco's PBS, respectively. AMP and IST flushing were assayed for protein using BCA assay kits (Pierce, Rockford, IL). AMP and IST weights were heavier (P < .01) in ME ewes than in FE and TE ewe lambs. AMP protein concentration patterns differed (P = .06) among FE, TE and ME ewes during the first five days of the estrous cycle, due to high concentrations on Day 0 for FE and TE ewes compared to that in ME ewes and by high concentrations in FE ewes on Days 3 and 4. IST protein concentrations did not differ (P > .10) among FE, TE, and ME ewes. P4 concentrations did not differ (P > .10) among FE, TE, and ME ewes, and increased (P < .01) between Days 1 and 4. E2 concentrations did not differ (P > .10) among FE, TE, and ME ewes; however, they were higher (P < .01) on Days 0 and 3 than on Days 1, 2, or 4. There was an interaction (P = .07) between day of cycle and reproductive status for P4 to E2 ratios among FE, TE, and ME ewes. This ratio increased between Days 2 and 3 and decreased between Days 3 and 4 in TE and ME ewes, whereas, there was no change between Days 1 and 3 in FE ewes. Developmental changes in ovarian steroid and oviductal protein secretion patterns occur during the first five days of the pubertal estrous cycle in ewe lambs. These changes may play a role in reduced fertility associated with breeding at puberty. .

Keywords: Puberty, Estradiol, Progesterone, Oviduct, Ewe lamb

This abstract is being presented at: 8:00 AM in session:
Puberty