Some factors affecting reproducibility in ultrasonic scanning of animals 1. Cattle

Abstract

SUMMARYSix Hereford and Shorthorn cross steers were ultrasonically scanned in parallel planes perpendicular to the spine. Scanning was performed at the level of each vertebra and extended from the head of the 9th rib to the articulation of the 3rd and 4th lumbar vertebrae. Scans of each live animal were compared with those of its hot carcass and related to dissected sections of the frozen carcass. In general, the difference between an ultrasonic estimate and the carcass measurement was found to depend on the anatomical parameter being investigated, the location on the animal at which measurement was made and the individual interpreting the scan. Results are presented for fat thickness, Mm. longissimi thoracis et lumborum depth, ‘A’, ‘B’ and area measurements. Possible explanations for some discrepancies between the ultrasonic and carcass measurements are discussed.Additional results showed that whilst judges are consistent within themselves, in general their interpretations of ultrasonic scans differ significantly from each other.

Real-time ultrasound (RTU) imaging methods for quality control of meats

“…At the end of the 1960s, a commercial unit of the primary system was introduced for live animal evaluation, using similar technology (Stouffer, 2004). This equipment -the Scanogram -produced in 1969 by Ithaco Inc. (Ithaca, NY), was in use until the mid-1980s for the majority of in vivo carcass evaluation studies using ultrasound (Miles et al ., 1972;Shelton et al ., 1977;Kempster et al ., 1982;Andersen et al ., 1983;Simm et al ., 1983). However, one of the major limitations of B-mode mechanical scanners for animal applications was the movement of the animal, which, being random, was the cause of inaccuracy of images and low repeatability of measurements (Hedrick et al ., 1962;Gooden et al ., 1980;Stouffer, 2004).…”

“…Indeed, in fat lambs, two or even three layers of subcutaneous fat can be formed, which can be problematic for the interpretation of images taken at the interface between skin and subcutaneous fat (Miles et al ., 1972;Silva et al ., 2005;Thériault et al ., 2009) and can lead to an underestimation of SFD. This underestimation can have serious implications when the RTU measurements aim to select animals with lean carcasses (Gibson and Alliston, 1983;Brethour, 1992).…”

A note on the velocity of ultrasound in living tissue

“…Such a method is objective and avoids many of the weaknesses of current sonar techniques which are subject to errors of interpretation (Miles, Pomeroy and Harries, 1972). Such a method is objective and avoids many of the weaknesses of current sonar techniques which are subject to errors of interpretation (Miles, Pomeroy and Harries, 1972).…”

The use of a danscanner ultrasonic machine to predict the body composition of Hereford bulls

“…The shape of the animals at these positions would require a differently shaped transducer head for good acoustic contact; initial trials using the Danscanner suggest that the machine was not suitable for measuring at these positions (J. P. Gibson and J. C. Alliston, unpublished results) but Miles and Fursey (1974) found that the velocity-of-sound technique may be suitable. Miles, Pomeroy and Harries (1972) outlined errors that occur with ultrasonic measurements. Three causes of errors were identified: misidentifying discontinuities in acoustic impedance with anatomical boundaries; the inability to recognize consistently multiple reflection artefacts; and the omission of data on the scans when the ultrasonic beam is not perpendicular to the anatomical boundary.…”