Administration of PGF2α at the moment of timed-AI using sex-sorted or conventional semen in suckled nelore cows with different intensity of estrus behavior

• Published in: Theriogenology 2021-10, Vol.174, p.169-175
• Main Authors: Diniz, Juliana Horta Wilke, Peres, Rogério Fonseca Guimarães, Teixeira, Ana Carolina Bahia, Riveros, José Andres Nivia, Noronha, Isabella Marconato, Martins, Cícero Fleury Guedes, Oliveira, Clara Slade, Pohler, Ky Garrett, Pugliesi, Guilherme, Oliveira, Leticia Zoccolaro
• Format: Article
• Language: English
• Subjects: Bovine; Dinoprost; Estrus behavior; ProstaglandinF2alpha; Sexed semen; Timed-AI
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2021.08.023

The aim of this work was to evaluate pregnancy rates (PR) and ovulatory characteristics of Nelore cows receiving PGF2α at the time of AI (artificial insemination) in a progesterone(P4)/estradiol-based timed-AI protocol. We also compared the effects of PGF2α treatment at AI in cows inseminated with conventional or sex-sorted semen, with the absence or expression of estrus. In experiment 1, a total of 701 suckled, multiparous Nelore cows from two commercial beef farms were submitted to the same protocol. All cows received a 12.5 mg (IM) injection of dinoprost tromethamine (Dinoprost; Lutalyse®; PGF treatment) at days 7 and 9 of a timed-AI protocol. Following P4 device removal (day 11; D11), AI was performed 48 h later with conventional or sex-sorted semen from two different sires. At AI, cows received an additional dose of 12.5 mg (IM) of Dinoprost (PGF treatment) or 2.5 mL (IM) of sterile saline (Control). Estrus behavior was determined at D11 by activation of an estrus detection device (Estrotect®). The overall PR was 32.8% (n = 348) at Farm 1 and 42.3% (n = 353) at Farm 2 (P = 0.01). Despite PR differences between farms, the same factors affected PR at Farms 1 and 2. Body condition score (P = 0.02), estrus behavior (P = 0.01), and type of semen (P