“…The observations were made over a two-year period , the sheep and pastures comprising part of an experiment at the CSIRO, Pastoral Research Laboratory, Armidale, described in more detail by George (1969). One hundred and thirty-five Merino and 135 Dorset Horn ewes of mixed ages were divided into three groups which were joined for either a winter (June-July ), spring (September-October) or summer (November-December) lambing.…”