Effect of capture, immobilization and handling on rectal temperatures of confident and fearful male mink

The objective was to compare response levels of stress-induced hyperthermia (SIH) in male mink from confident and fearful breeding lines. In experimen t 1, effects of capture by trap, immobilization and recapture by trap were compared (n = 20 juvenile males per group). Experiment 2 clarified of how c apture by trap and repeated temperature measurements in the tight trap posi tion affected SIH response (n = 9 males, aged 1-2 years per group). In expe riment 3, effects of capture by hand and short-term handling in arms on rec tal temperatures were evaluated (n = 11 juvenile males per group). Hyperthe rmic response in the mink was fast. Furthermore, treatments such as capture , recapture, immobilization in a trap and handling in arms were found to ev oke measurable temperature responses. After first capture, no significant d ifferences in SIH response between animals of different temperament lines w ere noted. However, fearful and confident animals tended to react different ly to trap immobilization; the fearful ones by increasing or maintaining th eir response levels, and confident ones by decreasing them. SIH response to recapture by trap was opposite In the temperament groups; after recapture SIH was significantly higher and lower in fearful and confident animals com pared with the first capture, respectively. It is concluded that systematic temperament selection has led to significant differences in stress respons es between animals selected for confident and timid behaviour. Higher stres s reactivity in animals from a fearful temperament line is the most plausib le explanation for the lower breeding success observed in previous studies.