Autoria: ROSSETTI, R. C.; PERDIGÃO, A.; SÁ FILHO, M.; NOGUEIRA, G. P.; MACHADO, R.; MEMBRIVE, C. M. B.; BINELLI, M.

Resumo: The objective was to compare pharmacological strategies aiming to inhibit prostaglandin F2 alpha (PGF2) synthesis (flunixin meglumine; FM), stimulate growth of the conceptus (recombinant bovine somatotropin; bST) and progesterone (P4) synthesis (human chorionic gonadotropin; hCG), as well as their combinations, regarding their ability to improve pregnancy rates in beef cattle. Lactating Nelore cows (N 975), 35 to 70 days postpartum, were synchronized and inseminated by timed artificial insemination (TAI) on Day 0. On Day 7, cattle were allocated into eight groups and received one of the following treatments: saline (S) on Days 7 and 16 (Group Control); S on Day 7 and FM on Day 16 (Group FM); bST on Day 7 and S on Day 16 (Group bST); bST on Day 7 and FM on Day 16 (Group bST FM); hCG on Day 7 and S on Day 16 (Group hCG); hCG on Day 7 and FM on Day 16 (Group hCG FM); bST and hCG on Day 7 and S on Day 16 (Group bST hCG), or bST and hCG on Day 7 and FM on Day 16 (Group bST hCG FM). The aforementioned treatments were administered at the following doses: 2.2 mg/kg FM (Banamine®; Intervet Schering-Plough, Cotia, SP, Brazil), 500 mg bST (Boostin®; Intervet Schering-Plough), and 2500 IU hCG (Chorulon®; Intervet Schering-Plough). Pregnancy diagnosis was performed 40 days after TAI by transrectal ultrasonography. Pregnancy rates were not significantly different among treatments. However, there was a main effect of hCG treatment to increase pregnancy rates (63.0 vs. 55.4%; P 0.001). Concentrations of P4 did not differ significantly among groups on Day 7 or on Day 16. However, consistent with the higher pregnancy rates, hCG increased P4 concentrations on Day 16 (10.6 vs. 9.6 ng/mL, respectively; P 0.05). We concluded that hCG treatment 7 days after TAI improved pregnancy rates of lactating Nelore cows, possibly via a mechanism leading to induction of higher P4 concentrations, or by reducing the luteolytic stimulus during maternal recognition of pregnancy.

Ano de publicação: 2011

Tipo de publicação: Artigo de periódico

Unidade: Embrapa Pecuária Sudeste

Palavras-chave: Embryo development, Prostaglandin, conceptus, luteolysis, progesterone