@conference {40816,
	title = {Prediction of carcass tissue weight in vivo using live weight, ultrasound or X-ray CT measurements},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {205-211},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Twenty-one Dorset Down ewe hoggets (49.4kg body weight, 9months  old) were scanned by ultrasound and X-ray computer tomography (CT).  Total carcass tissue (fat, muscle and bone) weights were assessed by the  Cavalieri procedure from 16-18 CT slices per animal. Additional CT slices  were taken at four anatomical reference sites; 7th thoracic (TV7), 2nd  lumbar and 5th lumbar vertebrae (LV5), and mid-shaft of the femur.  Subcutaneous fat depth and muscle depth were assessed over the last rib  using ultrasound. Body weight, ultrasound measurements and reference slice  carcass tissue areas were used to predict total carcass tissue weights by  multiple regression techniques. In combination with BW, single CT slices predicted tissue weight more  accurately than ultrasound measurements with BW for fat (R2=72-84\% vs.  63\%) but not for muscle (R2=79-87\% vs. 83\%) or bone (R2=62-66\% vs.  65\%). The best combination of two CT slices was TV7 \& LV5. In  combination with BW these improved prediction accuracy further (fat,  R2=92\%, muscle, R2=91\%, bone, R2=71\%). It is possible that data from a single CT slice predict carcass tissue weight  less accurately than expected due to anatomical registration errors despite  CT producing better quality images than ultrasound. These errors are  attributed to scanning protocol constraints for CT equipment.  Two or more CT slices need to be scanned in order to predict tissue weight  more accurately than ultrasound.},
	issn = {1176-5283},
	author = {Young MJ and Nsoso SJ and Logan CM and Beatson PR}
}
