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Performance of Finnish Landrace Crossbred Ewes under Accelerated Lambing. I. Fertility, Prolificacy and Ewe Productivity

Virginia Polytechnic Institute and State University^,2, Blacksburg 24061

Abstract

Seventy-one -Finnish Landrace, -Rambouillet (-Finn) ewes; 92 -Finnish Landrace, -Rambouillet (-Finn) ewes, and 20 -Suffolk, -Rambouillet (SR) ewes were compared over a 5-year period while lambing three times every 2 year. Ewes were bred in August, November and April, and they lambed in January, April and September. Litters were reduced to two lambs at birth (with some selection against smaller, weaker lambs) and lambs were weaned at 43 ± 10 days of age. Conception rates in August (90%), November (79%) and April (53%) differed (P<.005). Breed groups did not differ significantly in conception rate in August or November. In April, conception rates for -Finns (60%) were higher (P<.05) than those for -Finn (45%) or SR ewes (38%). In August and November, conception rate was 5% lower (P<.40) among ewes that lambed 2 to 4 months before breeding than among ewes that lambed at least 7 months before breeding. In April, ewes that lambed 2 to 4 months before breeding had a 23% higher (P<.001) conception rate than ewes that lambed at least 7 months before breeding. Litter size in January (2.21), April (2.46) and September (1.84) differed (P<.001). The -Finns averaged .48 more lambs per litter than did -Finns (P<.001) and .50 more lambs per litter than SR ewes (P<.001). Among ewes that entered the study, -Finns gave birth to 42% more lambs (P<.01) and weaned 24% more kilograms of lamb (P<.05) than did -Finns. The -Finns gave birth to 52% more lambs (P<.01) and weaned 38% more kilograms of lamb (P<.025) than did SR ewes. Among ewes that completed the study, the advantage of the -Finn in total number born and in total weight weaned decreased to 30% (P<.001) and 12% (P<.05), respectively, over the -Finn and to 41% (P<.001) and 17% (P<.10) over the SR.

¹ The contribution of Dr. R. C. Carter (deceased) in the design of this study is acknowledged.

² Dept. of Anim. Sci.