02041naa a2200325 a 450000100080000000500110000800800410001902400280006010000190008824501140010726000090022152010800023065000190131065000170132965000100134665000170135665000250137365000200139865000280141865000100144665000240145665000270148065300210150765300210152865300300154970000210157970000170160070000200161777300780163720548382016-10-20       1982    bl uuuu     u00u1 u    #d7 a10.4141/cjas82-1302DOI1 aHACKETT, A. J.  aReproductive performance of hormonally treated sheep maintained year-round in a controlled-light environment.  c1982  aSix experiments were conducted on hormonally treated ewes maintained year-round in a controlled-light environment in a breeding program designed to produce three lamb crops in 2  yr. Various combinations of fluorogestone acetate (FGA), prostaglandin F2  (PGF2 ) and pregnant mares' serum gonadotrophin (PMSG) were used to synchronize estrus in the ewes. There were no significant differences (P &gt 0.05) in fertility between FGA- and PGF2 -treated ewes when the ewes were having cyclic ovarian activity (cycling) at the time of treatment, i.e. in January and May in our system. Among ewes in the constant day-length lighting regime, fertility was lower in September than in January or May. Prolificacy ranged from 1.7 to 2.0 in the six experiments. Fecundity, a measure of the overall productivity, followed a similar pattern to fertility and was not significantly (P &gt 0.05) affected by the various treatments. These findings demonstrated the feasibility of maintaining a controlled 8-mo breeding program for sheep maintained year-round in a controlled-light environment.  aAnimal ecology  aReproduction  aSheep  aCiclo estral  aComportamento animal  aEcologia animal  aEficiência reprodutiva  aOvino  aReprodução animal  aSincronização do cio  aAnimal behaviour  aControlled light  aHormone treatment effects1 aROBERTSON, H. A.1 aDWYER, R. J.1 aWOLYNETZ, M. S.  tCanadian Journal of Animal Sciencegv. 62, n. 2, p. 1109-1117, Dec. 1982.