Ultrasonic evaluation of cattle

Abstract

ABSTRACTOne hundred and fourteen castrated male cattle of various breeds were measured ultrasonically immediately prior to slaughter and the data were examined for correlations with the proportion of adipose tissue in the carcasses. Two flaw detectors and a simple scanner, the Scanogram, were used to make ultrasonic pulse-echo measurements of tissue thicknesses and areas. These were used to compute volumes of adipose tissue and muscle in a region of the back of each animal and the ratio of the volumes of the two tissues was examined for correlation with carcass fatness. Three individuals interpreted the Scanogram photographs and two made measurements using flaw detectors.In general, pulse-echo measurements made by different individuals differed in magnitude and predictive value, even when identical scans were measured. Equally there were substantial differences between measurements when the same animals were measured by the same individual using different ultrasonic instruments.In a parallel experiment, the speed of ultrasound transmission was measured at various locations on the living animal and the data were examined for correlations with carcass fatness. Unlike the pulse-echo technique, the transmission method was not prone to errors of subjective interpretation and did not require skill to interpret. Predictions based on speed measurements at two sites in the hind limb were as well related to carcass fatness as were those made on the basis of the best estimate of tissue volumes in the back. The use of two speed measurements in a multiple regression with the best Scanogram data significantly improved the accuracy of predictions of side fatness made on the basis of speed or pulseecho measurements alone.Two types of analysis were used to examine the effectiveness of Ultrasonic selection of lean animals from a group of 50 Hereford castrated males of similar age and weight.