03711naa a2200361 a 450000100080000000500110000800800410001902400620006010000200012224501870014226000090032952026150033865000110295365000290296465000120299365000240300565000090302965300140303865300200305265300250307265300160309765300130311370000200312670000230314670000220316970000190319170000220321070000200323270000180325270000170327070000200328777300420330721357112021-10-29       2021    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1016/j.theriogenology.2021.08.0232DOI1 aDINIZ, J. H. W.  aAdministration of PGF2 alpha at the moment of timed-AI using sex-sortedor conventional semen in suckled nelore cows with different intensityof estrus behavior.h[electronic resource]  c2021  aThe aim of this work was to evaluate pregnancy rates (PR) and ovulatory characteristics of Nelore cows receiving PGF2a at the time of AI (artificial insemination) in a progesterone(P4)/estradiol-based timed-AI protocol. We also compared the effects of PGF2a 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 ¼ 348) at Farm 1 and 42.3% (n ¼ 353) at Farm 2 (P ¼ 0.01). Despite PR differences between farms, the same factors affected PR at Farms 1 and 2. Body condition score (P ¼ 0.02), estrus behavior (P ¼ 0.01), and type of semen (P &lt 0.001) were factors affecting PR. Conventional semen had a 2.73x greater chance of successful pregnancy than sex-sorted semen. Cows displaying estrus had a 2.5x greater chance of successful pregnancy than cows that did not display estrus. No treatment effect (P ¼ 0.67) was detected in cows receiving conventional or sex-sorted semen. However, there was a tendency (P ¼ 0.08) for an interaction between treatment (PGF or control) and estrus behavior (estrus or no estrus). PGF2a at the time of AI tended to increase PR of cows that did not display estrus (P &lt 0.10). In experiment 2, 29 suckled, multiparous Nelore cows were compared using B-mode and Doppler ultrasongraphy to assess the ovulatory characteristics of cows receiving the 12.5 mg (IM) injection of Dinoprost (PGF treatment) or saline solution (control) at D11. No significant effects of PGF2a treatment at D11 were observed in follicular characteristics and/or ovulation performance. It was concluded that fertility of sex-sorted semen was lower than conventional semen, regardless of the PGF2a treatment. The 12.5 mg treatment of Dinoprost at AI did not accelerate the occurrence of ovulation; however, it was interesting to note that PGF2a treatment at timed-AI appeared to increase the fertility of cows that did not display estrus, independent of semen type.  aBovino  aInseminação Artificial  aPrenhez  aReprodução Animal  aVaca  aDinoprost  aEstrus behavior  aProstaglandinF2alpha  aSexed semen  aTimed-AI1 aPERES, R. F. G.1 aTEIXEIRA, A. C. B.1 aRIVEROS, J. A. N.1 aNORONHA, I. M.1 aMARTINS, C. F. G.1 aOLIVEIRA, C. S.1 aPOHLER, K. G.1 aPUGLIESI, G.1 aOLIVEIRA, L. Z.  tTheriogenologygv. 74, 169e175, 2021.