Vesely J A, Swierstra E E
Research Station, Lethbridge, Alberta, Canada.
J Anim Sci. 1987 Nov;65(5):1195-200. doi: 10.2527/jas1987.6551195x.
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 (greater than 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.
选用了八种遗传类型的杂交母羊羔羊（多塞特×3/4多塞特，DD；多塞特×3/4芬兰羊，DF；芬兰羊×3/4多塞特，FD；芬兰羊×3/4芬兰羊，FF；罗曼诺夫×3/4多塞特，RD；罗曼诺夫×3/4芬兰羊，RF；罗曼诺夫×西方品种，RW；西方品种×西方品种，WW）来确定受孕时的年龄和体重、受孕率、排卵率、产仔数和产前死亡率。每个杂交组合在冬季、春季、夏季和秋季出生的五批不同羔羊中都有体现。所有批次的母羊羔羊都获得了较高的受孕率（大于88%），即使是6月份出生且同年接触公羊的那些。只有6月份出生且在出生年份接触公羊的西方母羊羔羊受孕率较低（59%）。10月份出生且错过出生年份繁殖季节的母羊羔羊比同年早些时候出生并繁殖的母羊羔羊大100多天。各批羔羊的产前死亡率差异很大（8%至18%），管理被怀疑是一个因素。罗曼诺夫羊在排卵率和产仔数方面的加性遗传效应与芬兰羊相似。罗曼诺夫杂交组合（RF、RD、RW）受孕年龄最小（226、227、231天），表明罗曼诺夫是一个早熟品种。
