Lamb Production of Targhee and Suffolk-Targhee Range Ewes

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Abstract
This study was conducted under primarily range conditions in southwestern Utah during an 8 year period from 1967 to 1974. The total sample size was 3,355 lambs and 2,255 ewes. Three breeding groups were included. Targhee ewes bred to Targhee rams (Tt), Targhee ewes bred to Suffolk rams (Ts), and Suffolk × Targhee crossbred ewes bred to Suffolk rams (STs). All ages from 2 through 9 years were studied for each breeding group. Ewes were bred on pastures each year in single sire groups beginning the second week of November, wintered on salt-desert-type range, shed lambed, held on spring pastures until early June and then placed on fenced mountain range during the summer. Analyses of pounds (kilograms) of lambs born and weaned per ewe bred were made using general least squares analysis. Significant main effects of breed, age and year were found for both pounds (kilograms) of lamb born and lambs weaned. The STs breeding group had higher lamb production than the Tt or Ts breeding groups at birth, 17.6 vs 14.4 and 14.9 lb (8.00 vs 6.54 and 6.77 kg), at weaning 127.2 vs 100.6 and 106.8 (57.69 vs 45.63 and 48.43), and greater proportion of twins (58.9 vs 45.6 and 41.8%). Differences in lamb production between Tt and Ts breeding groups were not statistically significant. The crossbreeding of the ewes had a greater influence on pounds (kilograms) of lamb born than crossbreeding of the lamb when measured at both birth and weaning. Lamb production was highest in ewes 4 to 7 years of age with the STs ewes being highest at each age and approaching the highest level at an earlier age. Overall lifetime lamb production for the STs ewes 215.4 lb (97.70 kg) more than the T1 ewes and 172.3 lb (78.14 kg) more than Ts ewes. Lambing rates followed closely and contributed to lamb production in terms of both breeding group and age. Average age of loss from the herd (6.09, 6.29 and 6.10 years for Tt, Ts and STS, respectively) and time of loss was similar for the three breeding groups. Results show that Suffolk × Targhee crossbred ewes are superior to straightbred Targhee or Targhee ewes carrying Suffolk-cross lambs under the range conditions studied. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science

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