Effects of flunixin meglumine, recombinant bovine somatotropin and/or human chorionic gonadotropin on pregnancy rates in Nelore cows

• Published in: Theriogenology 2011-09, Vol.76 (4), p.751-758
• Main Authors: Rossetti, R.C, Perdigão, A, Mesquita, F.S, Sá Filho, M, Nogueira, G.P, Machado, R, Membrive, C.M.B, Binelli, M
• Format: Article
• Language: English
• Subjects: Animals; artificial insemination; beef cattle; Cattle - blood; Cattle - physiology; Chorionic Gonadotropin - pharmacology; Clonixin - analogs & derivatives; Clonixin - pharmacology; Conceptus; cows; Dinoprost - antagonists & inhibitors; Dinoprost - biosynthesis; Embryo development; Female; flunixin; Growth Hormone - pharmacology; human chorionic gonadotropin; Insemination, Artificial - veterinary; lactation; Luteolysis; Male; Nellore; Pregnancy; pregnancy diagnosis; Progesterone; Progesterone - blood; Prostaglandin; prostaglandins; somatotropin; ultrasonography
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2011.04.008

The objective was to compare pharmacological strategies aiming to inhibit prostaglandin F2 alpha (PGF₂α) 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.