02707naa a2200265 a 450000100080000000500110000800800410001902400460006010000150010624501500012126000090027150001500028052017850043065000100221565000110222565300080223665300140224465300280225865300190228665300170230565300330232270000170235570000240237277300450239610564042017-01-02       2017    bl uuuu     u00u1 u    #d7 a10.1016/j.theriogenology.2016.11.0312DOI1 aFIERRO, S.  aLong term prostaglandin based-protocols improve the reproductive performance after timed artificial insemination in sheep.h[electronic resource]  c2017  aArticle history: Received 25 April 2016; Received in revised form; 28 September 2016; Accepted 30 November 2016; Available online 2 December 2016  aABSTRACT.  The aim of the experiment was to evaluate the reproductive performance of ewes synchronized with two doses of prostaglandin F2a (PG) at different intervals and inseminated at a fixed time. During the breeding season (April to June), 370 multiparous Corriedale ewes were assigned to five groups according to body condition score and body weight, and synchronized with two doses of PG administered 7, 10, 12, 14 or 16 days apart (groups PG7, PG10, PG12, PG14 or PG16; n ¼ 73, 76, 74, 72, 75; respectively). Cervical timed artificial insemination (Day 0) was performed at 48 ± 1.0 h (group PG7) or 56 ± 1.0 h (groups PG10, PG12, PG14 and PG16) after the second PG injection, with diluted fresh semen pooled from six adult rams. The percentage of ovulating ewes after the second PG injection and the ovulation rate (number of corpus luteum/ovulating ewes) were assessed on Day 10 by trans-rectal ultrasonography. The rate of non return to service (ewes not returning to service/inseminated ewes  100; NRR-21) was evaluated using painted vasectomized rams. Pregnancy rate (pregnant ewes/inseminated ewes  100) and prolificacy (foetuses/pregnant ewes) were determined on Day 60 by trans-abdominal ultrasonography. Higher NRR-21 and pregnancy rates was observed in groups PG12 (46.0%, 46.0%), PG14 (59.7%, 56.9%) and PG16 (58.7%, 56.0%) compared to PG7 (30.1%, 28.8%) and PG10 (30.3%, 30.3%; respectively P < 0.05). No significant differences were observed in the percentage of ovulating ewes, ovulation rate and prolificacy among groups (P > 0.05). Under the condition of this trial, 12, 14 or 16 days interval between PG injections enhances the pregnancy rate of ewes at cervical timed artificial insemination with fresh semen.  © 2016 Elsevier Inc. All rights reserved.  aOVEJA  aOVINOS  aEWE  aFERTILITY  aOESTRUS SYNCHRONIZATION  aOVULATION RATE  aPROTAGLANDIN  aTIMED ARTIFICAL INSEMINATION1 aVIÑOLES, C.1 aOLIVERA-MUZANTE, J.  tTheriogenology, 2017gv. 90, p. 109-113.