Abstract:
Animal Production in Australia AN EVALUATION OF THE MERITRONIC LIVESTOCK GRADER FOR ESTIMATING THE SUBCUTANEOUS FAT DEPTH OF LIVE CATTLE J.F. GRAHAM* , G.R. SAUL* and S.A. SPIKER* There is a need to accurately estimate the subcutaneous carcass fat of live cattle. The Meritronic Livestock Grader is an ultrasonic single device designed to measure fat depth and pregnancy status in live pigs. Pastoral Research Institute this probe has been calibrated and evaluated on cattle. depth probe At the for use The grader was used to predict the subcutaneous fat depth over the eye muscle at the 12-13th rib site on four groups of cattle; group 1, 72 steers of ten breeds; groups 2 and 3, 121 and 18 two-year-old Hereford steers, respectively, and group 4, 22 weaner steers and heifers. Groups 1, 2 and 3 were grazed at three locations and the animals within each group were slaughtered on the same day. Group 4 was slaughtered over a six-month period with a range of target fat depths of 1 to 10 mm, as predicted by the grader. Fat depth was estimated on all animals using the grader one day prior to slaughter. A final reading (skin and fat) was recorded on each animal only after two operators recorded the same value. Estimated fat depth (EFD) was then calculated by subtracting skin thickness from this value (determined by mechanically measuring the skinfold). Subcutaneous fat depth (SFD) was determined by averaging three measurements at the 12-13th rib site on the cold carcass 24 h after slaughter. TABLE 1 Relationships between subcutaneous (SFD) and estimated (EFD) fat depth (mm) These relationships show that good predictions of subcutaneous fat depth were obtained by using the meritronic grader on all groups. These figures compare favourably with those of Tulloh et al. (1973) and Gillis et al. (1973) who The Meritevaluated different types of ultrasonic devices for use in cattle. ronic Livestock Grader is a compact and easy to use device that can provide a relatively fast and accurate estimate of subcutaneous fat depth on live cattle. GILLIS, W.A., BURGESS, T.D., USBORNE, W.R., GREIGER, M. and TALBOT, S. (1973). Can. J. Anim. Sci. 53:13, TULLOH, N.M., TRUSCOTT, TT. and LANG, C.P. (1973). Report to Australian Meat Board. * Pastoral Research Institute, Hamilton, Vic. 3300 ? Meritronics Ltd., Otterden Place, Eastling, NR Faversham, Kent ME13 OBU.
