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Comparison of Finnish Landrace Crossbred Ewes with Columbia, Rambouillet and Targhee Ewes on Western Range^1,2,

Montanta State University, Bozeman 59717

⁴ To whom reprint requests should be addressed.

Abstract

The objective of this study was to compare reproductive efficiency and wool production of 1/4 Finn crossbred ewes with straightbred Columbia, Rambouillet and Targhee ewes. In Phase I, white-faces ewes (WF; Columbia, Rambouillet and Targhee) were bred to either rams of their own breed or Finnish Landrace x Rambouillet rams (F x R) to produce 821 lambs from 563 lambings. Ewes bred to F x R had similar average litter size and individual lamb weights at birth, 60 d and weaning as those bred to WF. Lambs sired by F x R had 7% higher (P < .01) survivability to 60 d than those sired by WF, resulting in 4.1 kg more (P < .01) lamb weaned per ewe lambing for ewes bred to F x R rams. For Phase II, approximately equal numbers of F x R-sired (1/4Fx) and WF-sired female lambs produced in Phase I each year were exposed to Suffolk rams at yearly intervals beginning at 7 mo of age. At 1 yr of age, 1/4Fx had higher fertility (P < .01) than WF (37.7% vs 1.3%), resulting in 14.0 kg more lamb weaned per ewe exposed to breeding. Mature (ages 2 to 6 yr) 1/4Fx ewes had similar fertility to mature WF ewes, but litter size, number of lambs at 60 d and weaning was .36, .24 and .22 lambs higher (P < .01), respectively, for mature 1/4Fx. Progeny of 1/4Fx were lighter at birth (P < .01), but not different (P > .05) at 60 d and weaning than those of WF. Survival to 60 d unadjusted and adjusted for birth weight was 4.6% (P < .05) and 7.6% (P < .01) higher, respectively, for 1/4Fx progeny than for WF progeny. Litter weights (per ewe exposed) at 60 d and weaning were 3.9 kg and 4.3 kg heavier, respectively, for 1/4Fx than for WF ewes (P < .01). Fleeces from 1/4Fx ewes, ages 1 to 6 yr, were lighter and coarser than those from WF ewes (P < .01), but they had similar staple lengths.

¹ Contribution No. 2061 from Montana Agric. Exp. Sta.

² This project was supported in part by a SR-CRSP grant from the Agency for International Development, Title XII, Grant No. DAN-1328-G-SS-4093-00.

³ Present address:Dept. of Anim. Sci., Oregon State Univ., Corvallis.