Supplementation with long-acting progesterone in early diestrus in beef cattle: II. Relationships between follicle growth dynamics and luteolysis

Autor(es)

Martins, T. ^[1] ; Pugliesi, G. ^[1] ; Sponchiado, M. ^[1] ; Cardoso, B. O. ^[1] ; da Silva, K. R. ^[1] ; Celeghini, E. C. C. ^[1] ; Binelli, M. ^[2]

Afiliação do(s) autor(es)

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

^[2] Univ Florida, Dept Anim Sci, Gainesville, FL 32611 - USA

• Tipo de documento: Artigo Científico
• Fonte: DOMESTIC ANIMAL ENDOCRINOLOGY; v. 68, p. 1-10, JUL 2019.
• Citações Web of Science: 0

Resumo

The aims were to characterize follicular dynamics in response to supplemental progesterone (P4) and to investigate the relationships between follicular growth and onset of luteolysis in P4-treated cows, submitted or not to artificial insemination (AI). Nonsuckled beef cows detected in estrus were assigned to receive AI or to remain non-AI. Three days after ovulation (ie, D3), AI cows were injected with 150 mg of long-acting P4 (AI + injectable P4 formulation {[}iP4]; n = 22), and the non-AI cows were assigned to receive 150 mg iP4 (n = 19) or saline (control, n = 19). Between D3 and D21, growth dynamics of the dominant follicles (DFs) was monitored by ultrasonography. Plasma P4 concentrations were measured every other day from D9 to D19. Pregnancy status (ie, P: pregnant and NP: nonpregnant) was examined by ultrasound on D28 to D32. Injectable P4 formulation supplementation decreased average maximum diameter of first-wave DF (DF1). Neither day of emergence of DF2 or DF3 nor the proportion of two- or three-wave cycles were altered by supplemental P4. Daily mean diameter of DF2 and DF3 was also similar between control and iP4 groups. Consistently, daily mean diameter of DF1 in iP4-treated cows was smaller for cows that underwent luteolysis by D15 compared to a later onset. Progesterone concentrations between D9 and D19 decreased earliest in the iP4 group, latest in the control group and was intermediate for the NP-AI + iP4 group. In addition, three-wave cycles presented a delayed decrease on plasma P4 concentrations than two-wave cycles. Further analysis revealed that on two-wave cycles, P4 concentrations on D15 were lowest in the iP4 and NP-AI + iP4 animals compared to the control and P-AI + iP4 groups. Conversely, for three-wave cycles, on D15, P-AI + iP4, NP-AI + iP4, and controls had greater P4 concentrations than the iP4 group. In summary, our data indicate that impairment of first follicular growth was associated with P4-induced shortened luteal life-span (D14-D15) and that three-wave cycles after AI can be more supportive for pregnancy maintenance in P4-treated cows. We speculate that such conditions play a critical role in the embryonic ability to inhibit iP4-induced early luteolysis reported in part I of this series. (C) 2018 Elsevier Inc. All rights reserved. (AU)

• Processo FAPESP: 11/03226-4 - Assinaturas da receptividade
• Beneficiário: Mario Binelli
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 15/26215-9 - Efeito do embrião sobre o processo luteolítico antecipado em vacas de corte suplementadas com P4
• Beneficiário: Thiago Martins
• Modalidade de apoio: Bolsas no Brasil - Doutorado