Growth and furring of mink (Mustela vison) given diets containing the β-adrenergic agonist, cimaterol

An experiment was conducted to evaluate the effect of dietary cimaterol, a β-adrenergic agonist, on growth, carcass characteristics and pelt quality of kit mink. The 40 standard dark and 40 sapphire mink kits were assigned to a control or to one of three treatment groups (five males and five females of each colour phase per group). Treatment consisted of the inclusion of 0·5, 2 and 5 mg cimaterol per kg (dry) of a standard ranch mink diet (control). All animals were weighed at the initiation of the experiment (24 July) and at 28-day intervals until 16 October. At slaughter (12 December) body weights were recorded and pelts measured for length and evaluated for fur colour and quality by experienced fur graders. Samples of fur from similar sites on each animal were removed for measurement of guard hair and underfur diameter. Frozen carcasses were analysed for protein and fat content. Mink final weight decreased with increasing concentrations of dietary cimaterol (P < 0·05). Pelt length, which was found to be highly correlated with body size, was also reduced by cimaterol treatment. Feeding 2 and 5 mg cimaterol per kg diet to male kits, and 5 mg/kg to female kits caused a significant reduction in the proportion of carcass fat and increased the proportion of carcass protein (P < 0·05). Fur fibre diameter for both guard hair and underfur was not significantly affected by dietary cimaterol. There was also no significant effect of cimaterol treatment on fur quality. Cimaterol treatment did not result in diversion of nutrients from body proteins to the synthesis of fur and pelt proteins. Results of this research indicate that oral administration of cimaterol to mink will be of little practical value in fur production.