The use of growth patterns of muscle measurements, chemical data, energy, and muscle weights to differentiate between normal and recovering muscle

Abstract

Twenty-eight Peppin Merino wethers were equally divided into two groups, a continuously grown group and a group which suffered a 6-week period of liveweight loss followed by recovery. Wethers in the continuously grown group were slaughtered over a range of liveweights; wethers in the restricted group were slaughtered over the same range of liveweights during the recovery phase. Each animal was totally dissected and individual muscles weighed. Several linear measurements and a cross-sectional area measurement were made of the longissimus muscle (M. longissimus thoracis et lumborum). Dry matter, ether extract, nitrogen, and energy measurements were determined for the total muscle tissue. The relationship of the high impetus and low impetus muscles to total muscle weight was determined. No significant effects of treatment were shown on any of the M. longissimus measurements nor on the chemical and energy values. The relationship of the weight of the low impetus muscles to that of total muscle was not significantly different between groups, but the same relationship for the high impetus muscles was highly significantly different. It is concluded that the weight relationship of high impetus muscles to total muscle is a sensitive test to differentiate between normal and recovering muscle. It cannot of course be applied in the live animal.