Influence of salbutamol administered as the single active enantiomer (R-salbutamol) on the growth performance and carcass characteristics of broiler chickens

Fawcett, J.P.; Ravindran, V.; Morel, P.C.H.; Zhang, M.; Ciofalo, V.B.; Spainhour, C.B.; Aberg, G.

Animal Science 78(1): 23-30


DOI: 10.1017/s1357729800053807
Accession: 004204840

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Salbutamol (albuterol) is a b-adrenergic agonist marketed as a racemic (50 : 50) mixture of R- and S-enantiomers (rac-salbutamol). Since only R-salbutamol is pharmacologically active and S-salbutamol has a longer half-life in humans, we examined R-salbutamol as a performance enhancer and repartitioning agent in domestic chickens. The effects of feeding diets containing R-salbutamol (5, 10 and 15 mg/kg diet) and rac-salbutamol (10 mg/kg diet) from day 21 to 42 post hatching on growth performance, carcass characteristics and tissue concentrations of R- and S-salbutamol in male and female broilers were compared with a control diet. R-salbutamol in the diet lowered the weight gains in both sexes, but the magnitude of reduction was greater in males as indicated by a significant R-salbutamol 5 gender interaction. R-salbutamol also lowered food intake and improved food conversion ratios in both sexes. The relative weights of breast muscle and leg muscle were significantly increased and the relative weight of the fat pad was significantly decreased in birds of both sexes given diets containing R-salbutamol. Carcass protein content increased and carcass fat content decreased but the differences were not statistically significant. A significant dose-response effect was observed for tissue concentrations of R-salbutamol in all tissues, except the fat. Performance and carcass parameters in chickens given the 5 mg/kg R-salbutamol diet were similar to those given the 10 mg/kg rac-salbutamol diet, but tissue concentrations of R-salbutamol were lower. Chickens given the 10 mg/ kg rac-salbutamol diet had higher tissue concentrations of salbutamol than chickens given the 10 mg/kg R-salbutamol diet and higher concentrations of S-salbutamol than R-salbutamol in liver and leg muscle. Overall, these results demonstrate that R-salbutamol is an effective repartitioning agent in broiler chickens.