Comparative performance of Dorper and Rambouillet ewes on West Texas range

The objective of this experiment was to compare overall productivity between Dorper (n = 96) and Rambouillet (n = 100) ewes in West Texas commercial production conditions. Ewes originated from private flocks and were mated to produce terminal cross or purebred lambs, depending upon the year. These ewes generated 1,091 records of reproductive performance and lamb weights. Ewe traits included weight at the beginning of the fall breeding season, fertility (ewes that gave birth per ewe exposed), condition score, lambing interval, and stayability to 9 yr of age. Mixed linear models included flock of origin and ewe as random effects. Fixed effects included the age of the ewe nested within year of record (P < 0.001 all analyses). Ewe longevity assessed using survival analysis included the effect of birth year of the ewe. Analyses of lamb birth weight and weaning weight included the type of birth (litter size: singles, twins, triplets) and sex (P < 0.0001) as fixed effects. Lamb weaning weight included lamb age in d as a linear covariate (0.33 ± 0.013 kg; P < 0.0001). Fertility did not differ between ewe breeds (P > 0.05). Dorper ewes had higher condition score (3.02 ± 0.08), more lambs born per litter (1.6 ± 0.05) and shorter lambing intervals (386 ± 6.6 d) than Rambouillet ewes (2.69 ± 0.077, 1.4 ± 0.05, 403.3 ± 6.1 d, respectively). Dorper ewe weight (66.9 ± 1.3 kg) and stayability (0.69 ± 0.03) tende...
Source: Small Ruminant Research - Category: Zoology Source Type: research