Comparing breeds of sheep in the feedlot or on pasture and in the feedlot

Ali, Arshad
Major Professor
M. Peter Hoffman
Allen H. Trenkle
Committee Member
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Animal Science
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Animal Science

A terminal sire study was conducted to evaluate production and carcass traits of Texel sired offspring compared to Suffolk and Columbia offspring. Breeding and lambing occurred on pastures during a 2-yr study. The lambs were weaned at an average age of 70 and 94 d and allocated to one of two finishing programs. The finishing programs were (1) direct to feedlot (FP1) and (2) pasture followed by feedlot (FP2). Lambs were slaughtered at an average weight of 57.8 kg. Birth weights, weaning weights and pre-weaning daily gains of lambs sired by Texel rams were similar to lambs sired by Suffolk rams but greater (P < .05) than lambs sired by Columbia rams. However, survival to weaning for lambs sired by Texel, Suffolk or Columbia rams did not differ. In a pasture lambing system an estimated 19.21 per ewe per year was saved through feed costs alone, as compared to more intensive shed lambing systems. After weaning Suffolk sired lambs gained faster ( P < .01) than Columbia and Texel sired lambs. Post-weaning average daily gains were greater (P < .01) in FP1 than FP2 and led to an increase of 31 d to reach slaughter weight for lambs that initially grazed as compared to lambs placed directly in the feedlot. Texel crossbred lamb carcasses had larger (P < .01) loineye area (LEA) than Suffolk and Columbia lamb carcasses. Backfat (BF) was also higher ( P < .05) in Texel than Suffolk crossbred lambs. Body wall thickness (BWT) was less (P < .10) in Texel and Suffolk crossbred lamb carcasses than Columbia lamb carcasses. Dressing percentage and quality grades were similar across sire breeds. Lambs finished in FP2 had more LEA (P < .05), and less BF (P < .10) and BWT (P < .01) than lambs finished in FP1. It was concluded that Texel rams used in a forage-based lambing system might have some potential for increasing lean mass in their offspring. However, increase in lean mass of Texel crossbred lambs is counterbalanced by slower growth rate than Suffolk and Columbia crossbred lambs. Grazing lambs prior to finishing in drylot improved leanness in lambs in this study.