Carcass quality can be improved by using CT assessed traits
Take Home Message: Genetic selection of hill sheep using CT scanning and ultrasound will improve carcass conformation compared with selecting for liveweight
Computer tomography and ultrasonic measurements provide an effective means of selecting for improved carcass composition. So says a study, carried out by UK scientists, which set out to investigate of the use of computer tomography (CT) to genetically improve carcass composition and conformation in Scottish Blackface sheep.
“The ultrasonic and CT measured traits were more highly heritable than the subjectively assessed traits,” said the Roslin Institute’s Elina Karamichou, who led the trial.
“Many of the traits were also affected by the maternal environment, as expected. And the ultrasonic and CT traits also showed high levels of genetic variation, which is the second requirement for making genetic progress,” she added.
After five years of selection on an index designed to improve both composition and conformation (the ‘CT index’), a large response was observed in the CT index, with genetic progress equivalent to 0.11 phenotypic standard deviations per year.
Miss Karamichou added that, judging by the genetic correlations, selection on the CT index should achieve a moderate improvement in conformation, price and slaughter weight, and a decrease in fat class.
“These changes were in fact seen for fat class, conformation and live weight. Conversely, selection on live weight at scanning would be expected to improve carcass and slaughter weight, and total price received, but have slightly deleterious impacts on carcass conformation score.”
Karamichou E, Merell BG, Murray WA, Simm G and Bishop SC: “Selection for carcass quality in hill sheep measured by X-ray computer tomography.” Animal 1, 3-11
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