HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vesely, J. A. Articles by Swierstra, E. E. Search for Related Content PubMed PubMed Citation Articles by Vesely, J. A. Articles by Swierstra, E. E.

Reproductive Traits of Ewe Lambs Representing Eight Genetic Types Born in Winter, Spring, Summer and Fall

Research Station, Lethbridge, Alberta, Canada, T1J 4B1

Abstract

Crossbred ewe lambs of eight genetic types (Dorset x 3/4 Dorset, DD; Dorset x 3/4 Finn, DF; Finn x 3/4 Dorset, FD; Finn x 3/4 Finn, FF; Romanov x 3/4 Dorset, RD; Romanov x 3/4 Finn, RF; Romanov x Western, RW; and Western x Western, WW) were used to determine age and weight at conception, conception rate, ovulation rate, litter size and prenatal mortality. Each cross was represented in five different lamb crops born in winter, spring, summer and fall. High conception rates (>88%) were obtained in all crops of ewe lambs, even in those born in June and exposed to rams the same year. Only Western ewe lambs born in June and exposed to rams in year of birth achieved low conception (59%). Ewe lambs born in October and missing the breeding season in the year of birth were more than 100 d older than ewe lambs born earlier in the calendar year and bred the same year. Prenatal mortalities varied widely (8 to 18%) among lamb crops, with management suspected to be a factor. Additive genetic effects in ovulation rate and litter size of the Romanov were similar to that of Finn. Romanov crosses (RF, RD, RW) conceived at the youngest age (226, 227, 231 d), demonstrating that Romanov is an early-maturing breed.