Studies in flock mating of sheep. 3. Effect of undernutrition of ewes during joining

Abstract

One hundred five-year-old Merino ewes in medium condition (44 kg) were fed at one-third of the maintenance level from the start of joining until 3-4 weeks post-coitum (P.C.). The mean decrease in liveweight in the 3-4 weeks was 1.5 kg/week. One hundred similar ewes were fed so as to maintain liveweight. A ram was joined with each group during daylight hours for 15 days, and the course of mating observed constantly. Ewes were killed either 1-2 days p.c. or 24-38 days p.c. There was no evidence of an effect of the under-nutrition on mating behaviour, number of spermatoza in the ewe genital tract, fertilization rate (89 per cent for both) or early embryo losses (7 per cent and 3 per cent). The relatively low embryonic loss appeared to be related to the low ovulation rate (1.16).