Effects of estradiol treatments on PGF(2 alpha) release in beef heifers submitted to estrous resynchronization 14 days after timed-AI

Author(s)

Motta, I. G. ^[1] ; Rocha, C. C. ^{[1, 2]} ; Bisinotto, D. Z. ^[1] ; Melo, G. D. ^[3] ; Junior, G. A. . A. . ^[1] ; Nishimura, T. K. ^[1] ; Diaza, A. M. G. ^[2] ; Castro, T. ^[4] ; Ginther, O. J. ^[4] ; Pugliesi, G. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sch Vet Med & Anim Sci, Dept Anim Reprod, Pirassununga, SP - Brazil

^[2] Univ Florida, North Florida Res & Educ Ctr, Gainesville, FL 32611 - USA

^[3] Texas A&M Univ Texas, Dept Anim Sci, College Stn, TX - USA

^[4] Univ Wisconsin Madison, Sch Vet Med, Dept Pathobiol Sci, Madison, WI - USA

• Document type: Journal article
• Source: DOMESTIC ANIMAL ENDOCRINOLOGY; v. 76, JUL 2021.
• Web of Science Citations: 0

Abstract

The effects of 17 beta-estradiol (E2) or estradiol benzoate (EB) on PGF2 alpha release were studied in bred-non-pregnant and pregnant Nelore beef heifers. The day of timed artificial insemination (TAI) was designated day 0 (D0), and a single treatment was given on D14. All heifers also received an intravaginal P4 device on D14, and were randomly assigned to three groups: Control (C, P4 device only, n = 12); E2 (1 mg E2 + 9 mg P4, n = 10); or EB (1 mg, n = 10). Blood samples were collected hourly for 8 hours after treatment (Hours 0-8) to measure plasma concentrations (pg/mL) of a PGF2 alpha metabolite (PGFM). The P4 device was removed on D22 and pregnancy was diagnosed on D28. Pregnancy rate was not different among groups (C, n = 7/12; E2, n = 5/10; EB, n = 5/10). More (P < 0.05) heifers had a CV-identified prominent PGFM pulse (peak of > 100 pg/mL) in E2 group (6/10) than in EB (1/10) and C (0/12) groups. Hourly concentration of PGFM for Hours 0 to 8 showed significant effects of group and hour and an interaction of group by hour but did not show an interaction of group or hour with pregnancy status. In preliminary post-hoc analyses, PGFM concentrations during Hours 0 to 8 and pulse characteristics were analyzed within each pregnancy status. For the non-pregnant heifers, a group-by-hour interaction was detected tentatively indicating an increase (P < 0.005) in PGFM concentrations in E2 group from Hours 4 to 6 and in EB group at Hours 5 and 6. Maximum PGFM concentration during Hours 0 to 8 did not differ (P > 0.1) between E2 (124 +/- 23) and EB (110 +/- 30) groups, but was greater (P < 0.05) in each group than in C (32 +/- 3). Furthermore, PGFM concentrations of pulses at the peak, amplitude, and area under pulse curve (pg/mL/h) were greater (P < 0.05) in E2 group than in C group whereas the EB group did not differ (P > 0.1) from the other groups. For pregnant heifers, no effects of group, hour, or their interaction were detected in PGFM concentrations during the hourly sessions, except that maximum PGFM concentration was greater (P < 0.05) in E2 than in EB and C groups. In addition, the number of prominent pulses was greater in E2 group than in Control or EB groups. In conclusion, PGFM increased earlier and in greater concentration combined for bred-non-pregnant and pregnant heifers treated 14 days after TAI with 1 mg E2 plus 9 mg P4 than with 1 mg EB. Tentatively, a positive effect for each of E2 and EB on PGFM concentrations was attenuated in pregnant heifers. (C) 2021 Elsevier Inc. All rights reserved. (AU)

• FAPESP's process: 17/18613-0 - Effects of ressynchronization of estradiol on day 14 after timed-AI on morphofunctional characteristics of corpus lute and uterus in Nelore females
• Grantee: Igor Garcia Motta
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 15/10606-9 - Innovations in the early pregnancy diagnosis in cattle
• Grantee: Guilherme Pugliesi
• Support Opportunities: Research Grants - Young Investigators Grants