Analysis of records of a Perendale flock III. Estimates of environmental effects on productive traits of mature ewes

Environmental effects on several production traits were estimated from data on 1724 2-year-old, 1160 3-year-old, 726 4-year-old, and 449 5-year-old Perendale ewes. This formed part of an analysis designed to calculate genetic parameters. Between-year differences were important sources of variation for greasy fleece weight, staple length, fibre diameter, quality number, and fleece character. Sheep reared as twins had fleeces that were lighter at all ages and were slightly coarser in fibre diameter at 2 and 3 years. Offspring of 2-year-old dams also had lighter fleeces at 2 and 3 years. The fleeces of single- and twinrearing ewes were about 0.1 and 0.2 kg respectively lighter than those of ewes that did not rear a lamb.