03248naa a2200289 a 450000100080000000500110000800800410001902400620006010000270012224501230014926000090027252023530028165000280263465000280266265000180269065000290270865000240273765300110276165300170277270000190278970000170280870000280282570000200285370000230287370000180289677300440291421333242021-08-10       2021    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1016/j.theriogenology.2021.03.0092DOI1 aFERNANDES, C. A. de C.  aTiming of early resynchronization protocols affects subsequent pregnancy outcome in dairy cows.h[electronic resource]  c2021  aThe aim of this study was to evaluate the outcomes of an early resynchronization protocol (Resynch)initiated at different timepoints after timed artificial insemination (TAI) and with unknown pregnancystatus. Holstein cows (n¼164) were submitted to the following TAI protocol: D0, insertion of anintravaginal progesterone (P4) device and 2 mg im estradiol benzoate (EB); D8, removal of P4 device andtreatment with 0.5 mg im sodium cloprostenol (PGF); D9, 0.1 mg im Lecirelin (LEC); and D10, TAI1. Cowswere then randomly assigned to Resynch protocols starting either on day 20 (Resynch20D,n¼82) or 25after TAI1 (Resynch25D,n¼82) with the insertion of a new P4 device and EB treatment. In both groups,P4 device was removed on day 8 after the beginning of Resynch, the same day of pregnancy diagnosis byultrasonography. In pregnant cows there was no further action. Non-pregnant cows were treated with0.5 mg im PGF, had a blood sample collected for serum P4 analysis and we measured and recorded thesize of the largest follicle and the presence or absence of a corpus luteum (CL). One day later, cows weretreated with 0.1 mg im LEC and TAI2 occurred 12e14 h later. The diameter of the largest follicle andserum P4 were compared between groups by ANOVA for the main effects of treatment, presence of a CL,and their interaction, whereas pregnancy per artificial insemination (P/AI) and the percentage of cowswith a CL on the day of ultrasonography were analyzed using the Chi-square test. Follicle diameter on day8 of Resynch was greater for cows in the Resynch20D group compared with Resynch25D (15.9±3.9 vs12.2±2.5 mm, respectively; P¼0.046). The Resynch25D group had a greater percentage of cows with aCL (51.9 vs 18.9%, respectively; P¼0.0008) and higher serum P4 (2.8±1.1 vs 1.7±0.8 ng/mL; P¼0.041)at the end of the protocol compared with Resynch20D. P/AI at TAI1 was 35.4 and 36.6% (P&gt0.10) forcows enrolled in Resynch20D and Resynch25D groups, respectively. P/AI to TAI2, after Resynch protocols,was greater in Resynch25D than Resynch20D (44.2 vs 22.6%, respectively; P&lt0.05). In conclusion,starting an early resynchronization protocol 25 days after TAI increases P/AI compared with starting 20days after TAI, and this was associated with a presumed greater proportion of cows with a functional CLat the moment of P4 device removal.  aArtificial insemination  aReproductive efficiency  aGado Leiteiro  aInseminação Artificial  aReprodução Animal  aBovine  aTAI protocol1 aPEREIRA, J. R.1 aSOUZA, V. O.1 aFIGUEIREDO, A. C. S. de1 aVIANA, J. H. M.1 aSIQUEIRA, L. G. B.1 aPALHAO, M. P.  tTheriogenologygv. 167, p. 61-66, 2021.