8 November 2010

2 minute read

Ultrasound tissue depths, measured before and after finishing, combined with live weight can predict fat weights and proportions in beef carcases and carcase quarters with high accuracy.

“Muscle weights and proportions can also be predicted with moderate accuracy,” the Scottish Agricultural College’s Nicola Lambe told delegates at this year’s British Society of Animal Science’s annual conference, held at Queen’s University, Belfast.

“Pre-finishing measurements alone give moderate predictions of composition traits and improve predictions when combined with post-finishing data. But the ability of these measurements to distinguish between animals with more of their fat or muscle in one quarter was poor,” she said, sharing the results of her team’s trial, which investigated the ability of ultrasound-measured fat and muscle depths to predict carcase composition and tissue distribution and to quantify the relative accuracy of predictions using ultrasound measurement taken at the start or end of the finishing period.

“Prediction equations specialised for different carcass regions, rather than the whole carcase, may be more appropriate to target certain markets or allow greater flexibility for selection,” she added.

Dr Lambe and her team measured live weight and ultrasound measurements on 52 crossbred steers and 10 heifers at the start and end of the finishing period.

Animals were slaughtered in batches, depending on weight and visual predictions of carcass grade, and one carcase side was fully dissected.

Three models were tested for each carcass trait that used liveweight and informative ultrasound data from pre-finishing, post-finishing, or pre-finishing and post-finishing.

“As expected, higher prediction accuracies were generally achieved using measurements taken post-finishing than pre-finishing, although combining both substantially increased the values,” said Dr Lambe.

Fat weights and proportions – of total carcass side – were predicted with higher accuracy than muscle traits. For muscle traits, weights were predicted more accurately than their proportions, whereas there was an opposite trend for fat traits.

“The proportion of the carcase side weight, consisting of muscle in the forequarter in particular, was poorly predicted using all models,” she added.