Diurnal activity patterns of farm mink (Mustela vison) subjected to different feeding routines

Abstract

Diurnal patterns and time courses of activity and feed availability were investigated in three generations of farmed mink (2003–2005) subjected to three different feedings routines; normal farm feeding (close to average ad libitum), ad libitum, and restricted feeding. The mink were fed daily at h12:00 (in 2005 at 13:00 h) and their activity were observed by hourly direct scanning during 24 h. On November 13, 2003 the feeding was postponed from 12:00 to 15:00 h and the activity observed from 9:00 to 17:00 h. The diurnal rhythm but not the average 24 h activity level differed between the mink on different feeding schedules. The diurnal activity rhythm in both the farm fed and the ad libitum fed mink consisted of three activity peaks; one around sunrise, one prior to feeding time, and one around sunset. However, the restrictively fed mink decreased their activity in the morning when feed was not available and increased their activity up to expected feeding time at noon and again around sunset. When feeding was postponed, the restrictively fed mink increased their activity up to expected feeding time, whereas the ad libitum or farm fed mink did not. The results indicate that mink fed restrictively synchronize their daily activity rhythm to the expected time of feeding. In addition, a high feeding motivation appears to be a precondition for circadian anticipatory activity in mink whereas anticipatory activity of mink fed ad libitum or close to ad libitum may be provoked by stimuli from the actual feeding procedure.