Eye Muscle Report Information
The Meat Index is a means to rank a group of young sheep with different liveweights, eye muscle dimensions and fat depth "C". This Index, using eye muscle and fat depth measurements as indicators, is a good way to estimate these proportions.
First a calculation is carried out to determine the average Eye Muscle Width (A), Eye Muscle Depth (B), and Fat Depth (C) for each kilogram of liveweight. This calculation is known as a linear regression and is used to plot a straight line on a graph through all the readings. (i.e. Eye Muscle Width plotted against Liveweight). Any measurement positioned above this line will have a positive deviation (above average for that liveweight), and any below the line will have a negative deviation (below average for that liveweight).
Once the deviations have been calculated for each measurement, a formula is used to calculate the Meat Index. The formula adds value for bigger eye muscle dimensions.and subtracts value for excessive fat depth.
These calculations are based on giving more emphasis on Eye Muscle Width than Eye Muscle Depth. Muscle width is more to do with the type of animal, e.g. shape and leanness. Depth is associated with the environment, e.g. feeding etc. and is subject to changes which would alter rankings if animals were under stress at time of scanning.
The formula does not give the leanest animals a higher Index as this group lacks constitution etc.
The meat score is best used on a uniform group of ram or ewe hoggets to rank that group. This would usually mean ram or ewe hoggets bred by a single breeder in a given year, and is a attempt to decrease the difficulties arising from confusion of animals from different studs.