01823naa a2200313 a 450000100080000000500110000800800410001902400310006010000190009124500770011026000090018752009740019665000200117065000240119065000230121465000110123765000130124865000170126165000140127865000170129265000260130965000120133565000100134765000100135765000170136765300300138470000180141477300770143215197282023-11-29       1967    bl uuuu     u00u1 u    #d7 a10.1530/jrf.0.01400612DOI1 aPARSONS, S. D.  aEffect of the ram duration of oestrus in the ewe.h[electronic resource]  c1967  aAbstract: A series of experiments is reported in which the effect on the length of heat of varying degrees of association of the sexes was studied in Merino sheep. Length of heat in all ewes was determined by teasing with vasectomized rams at 4-hr intervals. When present throughout oestrus, mating behaviour of rams and also of stilboestrol-treated (`masculinized') ewes, reduced heat length in experimental ewes by some 30 to 50%. The sight, smell and sound of the rams were not sufficient to reduce the duration of oestrus. However, neither mounting nor intromission were necessary components of the male behaviour for the effect to be fully expressed. Oestrous periods synchronized by injections of progesterone were as effectively shortened by the continuous presence of the rams. The ewes were most sensitive to the effect of ram activity between 4 and 8 hr after the beginning of oestrus, but oxytocin treatment during this time did not reduce oestrous duration.  aAnimal behavior  aAnimal reproduction  aDiethylstilbestrol  aEstrus  aOxytocin  aPharmacology  aPregnancy  aProgesterone  aReproductive behavior  aSeasons  aSheep  aOvino  aReprodução  aComportamento reprodutivo1 aHUNTER, G. L.  tJournal of Reproduction and Fertilitygv. 14, n. 1, p. 61-70, Aug. 1967.