“…It is also in agreement with the well-documented observation that the muscles of bulls are redder than those of steers (Seideman and Crouse, 1986 Moody et al, 1980;and Solomon and Lynch, 1988, in sheep;and Seideman and Crouse, 1986, in cattle). These changes are commonly explained as a consequence of the hypothyroidism that occurs during a period of undernutrition (Beverly et al, 1991 It is known that thyroid hormones regulate the expression of type IIB myosin isoform (MHC2b) (Bacou and Vigneron, 1988). The changes are accompanied by a decrease in the oxidative activity of the muscles of animals on a restricted diet (Raju, 1975;Howells and Jordan, 1978).…”