THE EFFECT OF PREMATING STRESS ON THE ONSET OF OESTRUS AND ON OVULATION RATE IN SCOTTISH BLACKFACE EWES

Abstract

In a previous experiment, Scottish Blackface ewes maintained in a stressful situation for the duration of a full oestrous cycle before mating had a lower ovulation rate than similar ewes maintained in a non-stressful environment to which they were accustomed (Griffiths, Gunn & Doney, 1970). The nonstressful environment was provided by group pens in a well ventilated but sheltered sheephouse and the stressful environment was created by similar pens on an exposed out-of-doors site with additional heavy rainfall simulated by an overhead spray system. The present experiment was carried out to investigate the effect on ovulation rate of shorter duration stress and of previous management. Experimental ewes were taken from two sources. Home-bred adult ewes, of the Scottish Blackface breed on the research station at Sourhope, Roxburghshire, were already accustomed to the additional handling, indoor housing, group feeding,