VARIATION IN REPRODUCTION AND PRODUCTION OF POLL DORSET EWES

Poll Dorset ewes were joined to Booroola Merino (n = 22) or Trangie Fe rtility Merino (n = 26) rams in single sire joinings during late summe r/autumn of 1978, 1979, 1980 and 1981. Rams were changed each year and there were 1678 individual ewe joinings. A maximum of 527 ewes were u sed in any one year, and they represented 14 studs and varied in age, reproductive history and liveweight. The traits, litter size, maternal lamb survival, lambs weaned per ewe lambing and weight of lamb weaned per ewe lambing (kg at 100 days) were analysed for the effect of year , stud, age, lambs born and ewe liveweight.