Effect of clenbuterol on growth, carcase and skeletal muscle characteristics in broiler chickens

Abstract

1. Male and female broiler chickens (144 in total) were given diets supplemented with clenbuterol (CB) at 0 (control) and at 1 mg/kg between 28 and 49 d of age to study the effect of CB on growth, carcase and skeletal muscle. 2. CB improved growth in males by increasing daily weight gain and final live weight and by lowering food conversion ratio. In females it changed the carcase composition by reducing abdominal fat pad and by increasing the proportion of protein. Consequently, carcase protein gain was increased in both sexes (11% and 16%, respectively). 3. Skeletal muscle weights were enhanced by between 6% and 22%. Muscle fibre diameters were increased in extensor hallucis longus (EHL) but not in gastrocnemius (GAS) muscle. This increase was more pronounced in females. EHL total muscle fibre number remained unchanged. The proportion of fast-twitch glycolytic fibres was increased at the expense of fast-twitch oxidative fibres in males only. Nuclear/cytoplasm and DNA/protein ratios tended to be decreased by CB. 4. From the elevated EHL muscle RNA/DNA, unchanged protein/RNA and translation activity it is suggested that CB stimulated protein synthesis at the pretranslational level. Reduced protein degradation is deduced from decreased neutral calcium-dependent proteolytic activity. 5. It is concluded that broiler chickens respond to long-term CB treatment as has been shown in various mammals. However, the sex-specific response in growth, carcase composition and skeletal muscle cellularity is more clearly apparent in broiler chickens.

<i>In vivo </i>Administration of β₂-agonist Clenbuterol and Subsequent Increase in Skeletal Muscle Mass in Neonatal Chicks

“…The data obtained in this study demonstrates that a single administration of clenbuterol to 6 days-old chicks induces increase in the skeletal muscle mass 24 hours after administration. This is in agreement with several other authors' work on the effect of clenbuterol on the skeletal muscle of birds, e.g., the weight of pectoral muscle and thigh muscles in broiler chickens were increased by dietary supplementation with clenbuterol for 3 weeks (Rehfeldt et al, 1997). Therefore, clenbuterol might have hypertrophic effects on skeletal muscle of birds as well as mammals.…”

“…In addition, rats received subcutaneous injections of clenbuterol at a concentration of 1 mg/kg body weight for 14 days showed skeletal muscle hypertrophy (Wineski et al, 2002). Also in birds, dietary supplementation with clenbuterol (1 mg/kg diet) for 3 weeks (between 28 to 49 days of age) improves growth and skeletal muscle characteristics in broiler chickens, i.e., both body and skeletal muscle weight were increased (Rehfeldt et al, 1997). Although administration of clenbuterol might be effective in improving skeletal muscle growth of chickens, the molecular mechanisms underlie the hypertrophic effect of clenbuterol on skeletal muscle of birds remains unclear.…”

Newly Combined Method of Molecularly Imprinted Solid-Phase Extraction with ELISA for Rapid Detection of Clenbuterol in Animal-Tissue Samples

“…Unfortunately, it has been illegally used as a feed additive in farm animals, especially in pigs, because of its metabolic effect, which causes increased muscle mass and decreased adipose tissues (Cardoso and Stock 1996;Rehfeldt et al 1997;Schiavetta et al 1990). Its abuse results in contamination in the human food chain, and some incidences of poisonings have been reported in humans after meat consumption (Barbosa et al 2005;Brambilla et al 1997).…”

Role of β-Adrenoceptor Signaling in Skeletal Muscle: Implications for Muscle Wasting and Disease

“…In fact, studies on cattle, sheep, and pigs have shown that the mechanism controlling tissue responsiveness to ␤-agonists varies from species to species, and even among different tissues within a species, primarily because of differences in the densities of each of the receptor subtypes (185,407). Considerable knowledge about the effects of ␤-agonists on skeletal muscle mass has come from the many studies examining the use of these compounds in livestock, especially with respect to their potential to improve meat quantity and to a lesser extent, quality (29,30,34,93,165,235,304,306,373,398). For a comprehensive analysis of technologies for controlling fat and lean deposition in livestock, including the use of ␤-agonists, the reader is referred to the review of Sillence (406).…”