Productivity and biological characters of Romanov sheep and their crosses with Swedish Fur Sheep rams

摘要

Three groups each of 25 Romanov ewes and 1 group of 25 Swedish Fur Sheep (SFS) X Romanov (F1) ewes were mated respectively with Romanov, SFS, F1 and Romanov ewes. In the 4 groups, the number of lambs produced was 61, 45, 51 and 59. Twinning percentage ranged among groups from 42.6 (group 1) to 62.2 (group 2), and triplet percentage from 25.4 (group 4) to 39.4 (group 1). The 8-month body weight of male progeny from the 4 breeding groups averaged 37.7, 44.7, 37.9 and 42.0 kg respectively. The percentages of meat + fat in the carcasses of 8-month-old lambs averaged 74.6, 79.7, 76.4 and 79.5, and loin-eye area 11.8, 13.7, 12.0 and 13.1 cm2. Progeny survival rate to 100 days of age was 88.5, 90.7, 92.2 and 91.5% in the 4 groups. The pelts of lambs of group 2 had a slightly larger area and a slightly greater thickness than those of the other groups.