Use of artificial light and day length to alter the life cycles of mink.

: Mink (Mustela vison) that had been raised on a farm were abruptly changed from ambient light at 42 degrees N latitude to an artificial light regimen corresponding to 45 degrees S latitude. The study was continued for 3 years and included three generations of mink. Animals were raised in a light-controlled room with partial temperature control that kept the temperatures between -3 and 26 C. Light schedules were changed weekly to correspond with changing day length. After an initial transition period of 9 months, the mink adapted so that their furring and reproductive cycles were in phase with the altered light regimen. Normal reproductive performance was observed in some males and females. However, the low percentage of both males and females that performed adequately makes the procedure economically unfeasible at this stage of our knowledge and experience. Possible causes of poor reproductive performance were: imprinting of previous light schedules on the animals, relatively high temperatures during breeding and improper light frequencies from artificial illumination.