Benchmarking maternal genetics in the lamb industry.

The design and early results from the national central progeny test for maternal sires in the lamb industry are presented. Sires are mated to Merino ewes at 3 linked sites (Cowra, Hamilton and Struan/ Rutherglen) to produce >25 1stX ewe progeny. IstX wethers are slaughtered at heavy carcass weights and 1 stX ewes are mated to terminal sires over 3 years. Sire EBVs for 1 stX meat traits from the first 21 sires tested in 1997 showed large variation for weight (+4.1 to -7.5 kg), fat (-6.9 to +6.0 mm GR) and muscle (+I .8 to -1.0 cm2 eye muscle area). 1stX daughters of the 12 sires tested at Cowra in 1997 were mated to Poll Dorset rams at 7 months of age. The sire mean daughter performance varied from 4.6*3.2 to 32.9+3.7 kg for total weight of lamb weaned per ewe joined (P<O.Ol). Sires varied and rankings changed for the components, ewes lambing, litter size, lamb survival and weaning weight. These preliminary results show the large impact of maternal sire selection on lamb productivity.