Effects of cimaterol on Finnish-Landrace wether lambs. 2. Growth and nucleic acid concentrations in selected skeletal muscles

Abstract

The effects of cimaterol on the growth and nucleic acid concentrations in selected skeletal muscles in purebred Finnish-Landrace lambs were examined. Lambs (initial bodyweight (BW) = 26.3 kg; n = 12/treatment) were individually offered a pelleted concentrate diet ad libitum which contained either 0 or 10 ppm cimaterol. An additional group (n = 6) were slaughtered at the beginning of the study. Half of each treatment group was slaughtered after 36 days of treatment and the remainder after 64 days. Selected muscles were dissected from the right side of each carcass. Muscle type was a significant source of variation for muscle weight and nitrogen content. Cimaterol increased (P < 0.05) the weight of the pool of skeletal muscles examined after 36 and 64 days of treatment and the mean nitrogen content after 64 days of treatment. After 64 days, the weights of the semimembranosus, quadriceps femoris and longissimus thoracis et lumborum muscles were increased (P < 0.05) but the weight of the semitendinosus, adductor, psoas minor, psoas major, infraspinatus and supraspinatus muscles were not affected by cimaterol treatment. Within the pool of muscles examined, cimaterol did not affect muscle distribution at either slaughter day. The allometric coefficient for growth of the psoas major was increased (P < 0.1) and that of quadriceps femoris and supraspinatus decreased (P < 0.01) by cimaterol treatment. The allometric coefficient of nitrogen deposition in the quadriceps femoris muscle was increased (P < 0.1) by cimaterol treatment. After 64 days of treatment, cimaterol decreased (P < 0.05) the RNA concentration in the semimembranosus, psoas major, supraspinatus and longissimus thoracis et lumborum muscles and the DNA concentration in the semimembranosus and quadriceps femoris muscles. It is concluded that the effects of cimaterol on skeletal muscle growth were largely muscle independent but that the mechanism of growth differed among muscles.