Effects of different feeding strategies during the winter period on behaviour and performance in mink females ( Mustela vison)

Abstract

Female mink used for breeding are slimmed during the winter to best prepare them for flushing immediately before the mating season. However, intensive and long-term slimming has a number of negative consequences e.g. a significant increase in stereotypies. The purpose of the study was to examine the effects of three different feeding strategies on the female’s body weight and behaviour during the winter as well as examine the effects of the feeding strategies on the reproduction results and physiological parameters. The three different feeding strategies were ad libitum (ADL) feeding from 16 October to 16 February, ad libitum feeding but with a substantial (SUB) diet from 22 December to 16 February, and restricted (RE) feeding from 16 October to 16 February. Thereafter, the three groups were fed according to the same feeding strategy. The study included a total of 180 female mink. Behavioural observations were made by focal sampling in December, January, February, and March. The females were weighed approximately every second week from August to March. During the lactation period, the females were weighed at parturition, and 2, 3, 4, and 7 weeks after parturition. Blood samples were collected in November, February, March, May, and June for clinical–chemical analysis. Fifty-three per cent of the females fed restrictively (RE) were observed carrying out stereotypies compared to 27% of the females fed ad libitum (ADL, SUB). The study has demonstrated that it was possible to reduce the body weight of the females by feeding them a low-energy feed, and that this treatment did not lead to an increase in the incidence of stereotypies in mink. The body weight was lower for stereotypic than for non-stereotypic females from the age of 4 months.