U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska
Date of this Version
2005
Abstract
Over a 2-year period, crossbred lambs resulting from the mating of Texel (T), Romanov (R), and St. Croix (S) rams with Polypay (P) and S ewes, were finished during the summer and late fall to determine feedlot performance and carcass characteristics. A total of 175 wether lambs of the five genotypes (R x P, R x S, S x S, T x P and T x S) were fed a high-energy diet for an average of 110 d (Experiment 1). Purebred St. Croix lambs weighed less (P < 0.05) at the beginning and end of the finishing period, had the lowest average daily gain (ADG) (P < 0.05), and the lowest Gain:Feed (P < 0.10) of the five genotypes evaluated. All five genotypes produced carcasses with a quality grade ≥ Choice. In a subsequent 2-year experiment (Experiment 2), 251 lambs sired by either Dorset or St. Croix rams from the ewes created in Exp.1 were used. Dorset-sired lambs were heavier (P < 0.10) at the end of the feeding period and had greater ADG (P < 0.10) than lambs sired by St. Croix rams. Wether lambs were heavier (P < 0.10), grew faster (P < 0.10) and ate more (P<0.05) feed than female lambs. Lambs from crossbred ewes were heavier (P <0.05) at the beginning and end of the finishing period and grew faster (P < 0.10) than lambs from purebred St. Croix ewes. When Dorset rams were used as the terminal sire, lamb feedlot performance was similar among the five ewe genotypes used in this study.
Comments
Published in Sheep & Goat Research Journal, Volume 20, 2005.