The repeatability of ultrasonic fat-depth measurements made on sheep up to 18 months of age

R.W. Purchas, A.L. Rae, R.A. Barton and A.D. Beach

Massey University, Palmerston North and Auckland Industrial Development Division, DSIR, Auckland

Proceedings of the New Zealand Society of Animal Production. 1981, 41: 133-139

Measurements of fat depth of M. longissimus at the 12th rib were made with an ultrasonic instrument on groups of live Southdown and Romney ewes and rams ranging from approximately 7 to 18 months of age. Weight-corrected fat measurements, calculated from double-log regression equations, were expressed as percentage deviation values.

In some groups a period of negative growth during late winter was followed by lower levels of fatness for the same weight. The repeatability of fat-depth deviations (in terms of intra-class correlations) ranged from 0.56 to 0.72 for the six groups. Corresponding measures for body-length deviations and withers-height deviations were in most cases less repeatable. Interrelationships between weight-corrected measures of fatness, length and height were inconsistent and generally not close.

Keywords: NZSAPAB;

Last Updated 12-09-1998