Portal de Periódicos da CAPES

Productivity of Arcott sheep and their crosses when lambs are raised with their dams

1992; Elsevier BV; Volume: 8; Issue: 4 Linguagem: Inglês

10.1016/0921-4488(92)90214-o

1879-0941

J.N.B. Shrestha, D. P. HEANEY,

Reproductive Physiology in Livestock

Abstract This study is based on analyses of genetic and non-genetic differences in survival and body weights of 2250 lambs, and ewe productivity based on 1151 ewe records. Lambs were derived from the Arcott breeds (Outaouais and Rideau; two synthetic dam strains developed at the Animal Research Centre, Ottawa, Canada), their two-breed crosses, the Finnish Landrace (unselected control), and specific three-breed crosses sired by the Canadian Arcott (a synthetic sire strain also developed at ARC) and the Suffolk breed. Year of birth, sex of lamb, age of dam or ewe, type of birth and rearing had important influences. Fertility, prolificacy, fecundity, gestation length and total lamb weights per ewe lambing were similar among the Outaouais and Rideau ewes, whereas Rideau ewes weighed more at breeding than the Outaouais ewes. The reproductive performance of Finnish Landrace ewes was similar to that of Outaouais and Rideau ewes. In contrast, Finnsheep lambs had significantly lower body weights at birth, 56 days and 91 days than those of Outaouais and Rideau lambs. Finnsheep ewes were lighter at breeding and produced less total lamb weight per ewe lambing. Crossbred ewes from inter-mating of the Outaouais and Rideau breeds were similar to their purebred contemporaries in prolificacy and total lamb weight per ewe lambing (at 56 and 91 d of age). Purebred ewes of the Rideau breed were more fertile than their crosses but did not differ in fecundity. There appeared to be an overall trend in favor of specific three-breed crosses compared to the Outaouais and Rideau breeds, and their crosses. Growth performance was similar in specific three-breed cross lambs derived from rams of the Canadian and Suffolk breeds mated to Outaouais and Rideau cross ewes. The results demonstrate improved productivity of the newly developed Arcott breeds and their crosses, in terms of outstanding reproductive ability and rapid growth.