title: Comparison of Finnish Landrace and Romanov as prolific breeds in a terminal-sire crossbreeding system.
abstract: Targhee ewes lambing to Romanov vs Finnish Landrace rams gave birth to .22 more lambs (P = .02) and had .15 more lambs alive at weaning (P = .11) but did not rear more lambs. Finnish Landrace x Targhee (FT) and Romanov x Targhee (RT) lambs were similar for preweaning survival and for all growth and carcass traits studied. Romanov x Targhee ewes were 14.2 +/- 6.2 d younger (P = .02) at their first estrus and 12.1 +/- 2.8 d younger (P < .01) at their first lambing than FT ewes. The ovulation rate of RT ewes exceeded that of FT ewes by .35 (P < .01). Romanov x Targhee ewes gave birth to .42 more (P < .01) lambs per ewe lambing, had .39 more (P < .01) lambs alive at weaning per ewe lambing, and reared .15 more (P = .03) lambs per ewe lambing than FT ewes. Embryonic survival, adjusted for ovulation rate, was greater (P < .01) for RT (88.3 +/- 3.3%) than for FT (80.0 +/- 3.7%) ewes. Lamb survival was similar for the two F1 crosses, with or without adjustment for number of lambs born. Overall survival (the proportion of ova that resulted in weaned lambs) was greater (P = .02) for RT ewes (77.6 +/- 4.2%) than for FT ewes (67.5 +/- 4.7%), at the same ovulation rate. When ewes were credited with all the lambs they gave birth to, RT ewes produced 4.6 +/- 1.8 kg more (P < .01) weight of lamb at weaning.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, ON, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Gallivan
authors.forename: R A
authors.initials: RA
authors.lastname: Kemp
authors.forename: Y M
authors.initials: YM
authors.lastname: Berger
authors.forename: L D
authors.initials: LD
authors.lastname: Young
mesh_terms: D000818:Animals; D000833:Animals, Suckling / Q000254:growth & development; D001947:Breeding; D003433:Crosses, Genetic; D005260:Female; D016018:Least-Squares Analysis; D016014:Linear Models; D008098:Litter Size / Q000235:genetics*; D008297:Male; D012756:Sheep / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D015996:Survival Rate; D014886:Weaning; D015430:Weight Gain