Progeny testing of Suffolk rams on three maternal breeds

Abstract

1. Six Suffolk rams (two purchased from each of three breeders) were each progeny tested on 10 Scottish Halfbred (Border Leicester ♂ × North Country Cheviot ♀), 10 Welsh and 10 Clun ewes. The progeny of the Clun ewes were reared at a different location from the progeny of the Halfbred and Welsh ewes.2. Progeny were weighed at birth and every 3 or 4 weeks thereafter so that 56 and 112 day weights could be calculated. Growth rate was considered for the periods 0–8 weeks, 8–16 weeks and 0–16 weeks. The growth rates were corrected for birth type and sex, but not for birth weight. The growth rates of a ram's progeny for a ewe type were converted into a deviation from the mean of all progeny of that ewe type, and measured in standard deviation units. An overall deviation for all ewe types for each ram was also calculated; 0–16 weeks was considered the best period over which to compare ram progeny performance and the difference between the best and worst ram for this trait represented 0·81 of a standard deviation or a 10% increase in growth rate for the progeny of the best ram over the progeny of the worst ram. There was some evidence of ram × ewe-type interaction for this trait.3. A number of progeny of each ram were sent to a central abattoir and dissected into commercial joints. All pieces were weighed and a total carcass value obtained by multiplying each joint weight by an average retail price per pound and summing. The total carcass value was converted to terms of yield in pence per pound. Subjective assessments were made for colour and texture of meat and for tenderness and flavour of cooked meat. There was little variation between ram progeny groups for any of the carcass traits.