Kits start ingesting solid food at about four weeks of age (e.g. Jonasen 1987, Møller 1991b). Placing food on the nest-box lid, rather than on the cage top, accelerates their intake of solid food (Møller 1996). It also reduces inter-kit aggression: fighting occurred in 1% observations when kits were fed on the cagetop, but only 0.2% if fed on the nest box lid, and deaths from fighting/cannibalism occurred in 2.1% of the former group, none at all in the latter (Møller 1996). Female kit growth rates are also affected by feeding levels at this time, as if they are prone to lose out in competition with their brothers when food is not DG OLELWXP. The nature of the mink food itself also raises further, unexplored and lifelong welfare questions. First, it is a soft paste, very unlike the whole-carcass-based diet of the wild (e.g. Dunstone 1993), yet whether the lack of chewing it requires then affects digestive processes, motivations to chew, levels of fur-, mesh- or drinkerchewing, or the incidence of dental disease, has not yet been investigated. Second, on some farms (in Finland in particular), fox food may be fed to mink, even though mink are less able than foxes to digest high levels of fat or carbohydrate, and some potentially useful preservatives are not well metabolized by mink. The effects of these possibly sub-optimal diets on mink welfare still need to be investigated. Kits start to drink from nipple drinkers at about six weeks. Water-drinking can be accelerated by one week by providing ‘drip watering systems’ which provide a modified drinking nipple that drips continuously (Møller and Hansen 1993). Minks’ need for water increases with temperature, and in warm summers, drip watering systems can increase kits’ rate of weight gain (Møller 1991a), as can the provision of water-sprinklers. Whether such practices also increase kit (and adult female) welfare has been little investigated. Intra-litter aggression does not appear to be reduced by providing a water-tray. However, detailed studies of drinking do show that mink drink about every two hours, night and day, thus suggesting that these animals should always have DG OLELWXP water (Møller and Hansen 1993); and at ambient temperatures above 35oC, the restrictions of water can result in cortisol increases. :HDQLQJ The process of weaning Various forms of weaning exist. Kits may be weaned via the removal of the mother, with the litter then left intact for a period; or they may be removed themselves, usually in pairs, from the natal cage. The welfare effects of weaning by removing the mother from the cage do not seem to have been studied. The effects of re-caging young have, however. Kits may be carried manually, or transported in small carrying cages, which causes an acute cortisol response (a doubling of plasma cortisol within two hours, an effect not seen if the kits are fed tranquilliser). It may also cause a reduction in the proportion of leucocytes consisting of eosinophils. This process is usually also accompanied by vocalisation, urination and defecation on behalf of the kits. All kits, whether weaned at 7 - 8 weeks or c. 12 weeks, ‘croak’ in the first days after weaning, and even paired mink kits aged 8.5 - 13.5 weeks will persistently vocalise when experimentally exposed to novel experimental situations without their mothers, and scratch at the barrier separating them from her. Being placed in the new cage also elicits the young animals’ first incidence of brief stereotypy-like head-twirls,
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