Invasive Species Compendium

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Abstract

Growth and carcass characteristics of crossbred lambs by ten sire breeds, compared at the same estimated carcass subcutaneous fat proportion.

Abstract

An evaluation was carried out over a 5-yr period in 10 commercial flocks of Scottish Blackface, Scottish Halfbred or Mule ewes (each flock consisting of ewes of 1 breed type) to evaluate 10 sire breeds: Border Leicester, Dorset Down, Hampshire Down, Ile-de-France, North Country Cheviot, Oxford Down, Southdown, Suffolk, Texel and Wensleydale. An average of 43 sires was used per breed. The analysis involved a total of 3360 lambs, of which one-third subsequently had the left side dissected. Sire breeds were compared following slaughter of their progeny at the same estimated carcass subcutaneous fat proportion (approx. 120 g/kg body weight). Carcass weight was related to the adult body size of the sire breed, with a range of 4 kg between that of the Southdown (smallest) and that of the Wensleydale (largest) crossbreds. Crossbreds involving the conventional meat-sire breeds tended to have higher daily carcass-weight and lean-tissue gains than those involving Border Leicester or Wensleydale sires. Texel and Suffolk crossbreds did not differ significantly in carcass weight, daily carcass weight gain, daily lean gain or age at slaughter. Sire-breed Ă— dam-breed interactions were recorded for daily carcass weight gain and daily lean gain (P<0.05). Dorset Down and Southdown crossbreds tended to grow relatively faster when from Mule dams than from other dams; Texel crossbreds grew relatively faster when from Blackface dams than from other dams. There was relatively little difference between sire breeds in visually assessed carcass conformation; all the means were within 2 points on a 15-point scale. Texel crossbreds had a higher carcass lean proportion than other crosses; their advantage over Suffolk crossbreds was 22 g/kg.