OPEN-VS. CLOSE-FACED SHROPSHIRES

Abstract

In 1948 the Shropshire ewe flocks at the Central Experimental Farm, Ottawa, Ontario, and Experimental Farm, Nappan, Nova Scotia, were divided on the basis of face cover into two lots of approximately 20 each. The lots with least face cover were bred to British type, open-faced rams; the lots with most face cover to close-faced, or American type rams. Each lot was bred to at least one ram, with the rams being changed, in so far as possible, each year. In the 7-year period, 11 rams of the open-faced type, and 13 of the close-faced type, were used at the two Farms. Three of the open-faced type were used at both Farms. Average weights of the ewes in the Ottawa flock were equal at time of division.The open-faced type sired lambs were superior to the close-faced in birth weight, 14-day weight, 28-day weight, weaning weight, yearling weight, market weight, and age at marketing.Average weight of both types of ewes increased during the test period, but the open-faced, British type group increased faster than the close-faced, American type.There were no differences in fleece count in the two types at either Farm; but the open-faced type ewes had slightly heavier fleeces, this being significant in the Nappan flock only.Within the limits of the flocks at these two Farms, the superiority of the open-faced, British type of Shropshire is illustrated. However, this type is considerably larger than the more common close-faced, American type, and at least part of the advantage shown may be due to "grading-up" to this larger type. Heterosis, resulting from such wide out-crossing, also may be a contributing factor.