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Genetic evaluation of ewe performance in Outaouais Arcott and Suffolk sheep and their crosses

1996; Canadian Science Publishing; Volume: 76; Issue: 1 Linguagem: Inglês

10.4141/cjas96-002

1918-1825

A. M. Shafto, G. H. Crow, R. J. Parker, W. M. PALMER, J.N.B. Shrestha, P. B. E. McVetty,

Genetic Mapping and Diversity in Plants and Animals

Ewes from a newly developed sheep breed in Canada, the Outaouais Arcott, consistently out-performed Suffolk ewes in prolificacy at birth and at 42 d of age by 0.37 lambs at first parity and by 0.55 and 0.41 lambs, respectively, over all parities. In contrast, mean litter weights of Suffolk and Outaouais ewes did not differ at these times. Additive genetic effects in prolificacy and litter weight tended to favour the Outaouais breed over the Suffolk breed at first parity. Corresponding values over all panties were significant, favouring the Outaouais, for both prolificacy and litter weight at 42 d of age. Suffolk ewes excelled in maternal genetic effects for litter weight for all parities at birth and 42 d of age. Reciprocal cross ewes of the Outaouais and Suffolk breeds were similar (P > 0.05) in prolifacacy and litter weight. In general, crossbred ewes consistently exceeded Suffolk ewes in prolificacy but were not significantly different from Outaouais ewes. Though not always significant, crossbred ewes exceeded the average of their purebred parents m prolifacacy and litter weight. Furthermore, estimates of heterosis were always positive, and the 19% value for litter weight at 42 d of age at first parity was significant. This study, conducted over 6 yr, demonstrates the superiority of the Outaouais breed for production of commercial crossbred ewes to perform in a moderately intensive, semi-confinement operation. This superiority exists in addition to the previously-established ability of the Outaouais ewe to produce large litters in an 8-mo breeding cycle. Key words: Ewes, prolifacacy, litter weight, genetic effects, heterosis