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Effects of Substituting Finnsheep and Dorset Breeding for Rambouillet Breeding. I. Productivity of Young, Spring-Lambing Ewes¹

Oklahoma Agricultural Experiment Station, Stillwater 74074

Abstract

The main effects of increasing Dorset and Finnsheep breeding by at the expense of Rambouillet breeding on ewe productivity traits when lambing at 1, 2 and 3 years of age in late winter-early spring were estimated. One-hundred-ninety-eight crossbred ewes representing four combinations of Finnsheep (F), Dorset (D) and Rambouillet (R) breeding (R, D R, FDR and FDR) started the study. The comparison of the Dorset ewes with the Dorset ewes estimated the main effect of increasing Dorset breeding by at the expense of Rambouillet breeding ( Dorset effect) and the comparison of the Finnsheep ewes with the 0 Finnsheep ewes estimated the main effect of increasing Finnsheep breeding by at the expense of Rambouillet breeding ( Finnsheep effect).

The Finnsheep effect resulted in little change (P>.05) in ewe breeding weights at all three ages, a decrease (P<.01) in grease fleece weights of 1- and 2-year-old ewes and a decrease (P<.01) in quality grades of 1974 fleeces. The Dorset effect resulted in decreased (P<.01) ewe breeding and grease fleece weights at all three ages and in decreased (P<.01) quality grades of 1974 fleeces.

When lambing at 1 year of age, the Finnsheep effect resulted in an increase (P<.10) of 3.5 kg in weight of lamb weaned per ewe exposed due primarily to a greater (P<.01) proportion of the Finnsheep ewes lambing than the 0 Finnsheep ewes (+24%). When lambing at approximately 2 and 3 years of age, the Finnsheep effect resulted in little change in weight of lamb weaned per ewe exposed. At all ages, the Dorset effect resulted in little change in weight of lamb weaned per ewe exposed.

¹ Journal Article 3206 of the Agricultural Experiment Station, Oklahoma State University, Stillwater. Research was conducted by the Department of Animal Science (Project 1519) in cooperation with the USDA, Agricultural Research Service, Southern Region. Project 1519 is a contributing project to North Central Regional Project 111-Increased Efficiency of Lamb Production.

² Present address: Department of Animal Science, Oregon State University, Corvallis 97331.