Mink (Mustela vison) are housed individually in raised wire mesh pens. A nest box with a hole for entry is attached outside or placed within the pen. Wood used for the nest box should not be painted or treated with wood preservatives. Soft, awn-free marsh hay, chopped straw, untreated wood shavings, or fine wood-wool make suitable nest material. Nest boxes should be cleaned and nest material replaced as required, especially before whelping. Sheds are used throughout the year and should admit natural daylight. There should be plenty of air circulation and shade in the warmer months.
Mink feed may be supplied as a wet gruel placed on top of the wire mesh or as a commercially prepared, dry, pelleted ration placed in feed hoppers. During the weaning and postweaning periods, food is supplied on feeding trays placed on the floor of the pen for small kits that cannot reach the top of the pen. Fresh water should always be available. Watering cups fastened to the outside of the pen with a lip protruding inside are commonly used. Automatic watering systems with individual nipples or flotation cups are used in sheds, temperature permitting.
Cold storage facilities are necessary to freeze and store the meat portion of the ration. A day's supply of fish and meat byproducts is thawed, commercial cereal and vitamins added, and the combined ration mixed with water to a consistency that will remain on the wire of the pen without dropping through. Ready-mixed feeds may be delivered daily, either ready to feed or in frozen blocks that are thawed as required. Dry pelleted diets are used on some ranches for part or all of the year.
Ranchers usually keep 1 male for each 5 female breeders. Mink are seasonal breeders, with sexual activity controlled by increasing periods of daylight. Artificial lights in the sheds must be used with caution because they may adversely affect photoperiod and interfere with the normal reproductive cycle. In the northern hemisphere, the breeding season begins in late February or early March and lasts ∼4 wk. Mating should occur within 1 hr after the female is placed in the male's pen. If fighting ensues, they should be separated. Ovulation is induced by coitus. Females mated before mid-March are usually mated again after 7–8 days, often with an additional mating the following day; thus, individual females may be mated 2 or 3 times. Ova from 2 matings have been known to develop in the same litter. Implantation of the fertilized ova is delayed, so the apparent gestation period is 40–75 days.
Mink have one annual litter of 1–12 kits (average 4). Most kits are born during the last week in April and the first 2 wk in May. Kits are blind, hairless, and weigh ∼10 g when born but grow rapidly throughout the summer to reach a weight of ∼800 g (females) or 1,600 g (males) by October. Kits are weaned at ∼6–8 wk of age and may be separated shortly thereafter and housed in single pens. Adult mink are extremely agile, strong, and vicious. Handling requires the use of special leather gloves or wire catching cages.
Pelt collection usually is done in November or December. The most humane way to kill mink is with carbon monoxide. In the USA, mink farms are certified under the strict criteria for the humane treatment of animals by the United States Fur Commission.
Last full review/revision April 2012 by John R. Gorham, DVM, PhD