02803naa a2200313 a 450000100080000000500110000800800410001902200140006002400430007410000240011724501530014126000090029450001540030352017640045765000150222165000100223665000110224665000140225765300080227165300140227965300400229365300090233365300190234265300180236170000120237970000170239170000150240877300660242310538962019-10-31       2013    bl uuuu     u00u1 u    #d  a0378-43207 a10.1016/j.anireprosci.2013.02.0132DOI1 aOLIVERA-MUZANTE, J.  aReproductive outcome with GnRH inclusion at 24 or 36h following a prostaglandin F2&#945;-based protocol for timed AI in ewes.h[electronic resource]  c2013  aArticle history: Received 2 October 2012 / Received in revised form 19 February 2013 / Accepted 21 February 2013 / Available online 28 February 2013.  aABSTRACT.  The objective of this experiment was to study the reproductive performance obtained after a short-interval prostaglandin (PG) F2&#945;-based protocol for timed artificial insemination (TAI) in sheep (Synchrovine®: two injections of PG 7 d apart), including a GnRH analogue at 24 or 36h after the second PG injection. The experiment involved 296 Corriedale ewes (206 multiparous and 90 nulliparous) grazing natural pastures during the breeding season (March-April; UTU " La Carolina" , Flores Uruguay, 33° S-57° W). Ewes were assigned to three treatment groups: a) Synchrovine® (Control, n=101): two injections of D-Cloprostenol 75&#956;g, 7 d apart, b) Synchrovine®+GnRH24 (n=98): Synchrovine® plus GnRH (busereline acetate 8.4&#956;g) 24h after the second PG injection, and c) Synchrovine®+GnRH36 (n=97): Synchrovine® plus GnRH 36h after the second PG injection. All ewes were subjected to cervical TAI (Day 0), 44 to 47h after second PG injection, with fresh extended semen pool from six rams. Reproductive performance of ewes having ovulations and ovulation rate on Day 10, estrous cycle length in ewes that returned to estrus and non-return rate to estrus up to Day 22, fertility, prolificacy and fecundity on Day 70 were analyzed. Ewes having ovulations, ovulation rate, estrous cycle length and prolificacy did not differ between groups (P>0.05). However, non-return to estrus, fertility and fecundity was decreased in Synchrovine®+GnRH24 (P<0.05) and similar between Synchrovine® and Synchrovine®+GnRH36 (P>0.05). It was concluded that the reproductive performance obtained by Synchovine® TAI protocol was impaired by GnRH at 24h and not improved by GnRH administered at 36h after the second PG injection.   © 2013 Elsevier B.V.  aFERTILIDAD  aOVEJA  aOVINOS  aOVULACION  aEwe  aFertility  aFixed timed artificial insemination  aGnRH  aOvulation rate  aProstaglandin1 aGIL, J.1 aVIÑOLES, C.1 aFIERRO, S.  tAnimal Reproduction Science, 2013gv.138, no.3-4, p. 175-179.