Farm-bred Mink Research Articles

Effect of vitamin E supplementation on α-tocopherol status and tissue antioxidants in American minks ( Neovison vison )

The α-tocopherol (TCP) state as well as enzymatic (superoxide dismutase [SOD] and catalase [CAT]) and nonenzymatic (reduced glutathione [GSH] and retinol) antioxidants in tissues of American minks (Neovison vison) given various levels of dietary vitamin E were examined. Three groups of farm-bred minks received different amounts of DL-α-tocopheryl acetate (10 mg/kg diet, control; 30 and 110 mg/kg diet, treatments denoted as E30 and E110, respectively) for 14 days in November. The TCP content was raised substantially in the kidneys and reduced in the livers of minks in the E110 group. The action of the 2 vitamin E doses on antioxidants was similar. The treatments resulted in lower hepatic and kidney retinol levels and hepatic and skeletal muscle SOD, as well as hepatic CAT activities, higher heart SOD activity, and higher kidney GSH content in comparison to the control group. The present results show that dietary vitamin E intake over 2 weeks considerably changed the TCP status of the liver and kidneys and had tissue-specific action on measured antioxidants in minks. With the exception of the heart SOD activity, the additional intake of vitamin E reduced antioxidant enzyme activity and augmented the GSH level, indicating an enhancement in the nonenzymatic part of the antioxidant network.

Development of indices to estimate fat reserves in the wild American mink (Neovison vison)

Insight into body fat dynamics of wild mustelids could help to monitor changes in their nutritional status. Adipose tissue depots of wild American mink (Neovison vison, n = 50) were dissected to determine how fat was distributed throughout the body and to develop practical and reliable indices to estimate percent body fat in harvested mink. The average percent body fat of mink caught between July and April was 6.2 %, which is very low compared to previously studied farm-bred mink (adult females in summer = 20 %, subadult males in winter = 38 %). Most of the dissected adipose tissue was located in the subcutaneous (SC) fat layer (≈81 %) confirming earlier data on farmed mink. The total fat masses were higher in the subadults/adults than in the juveniles and in the male mink compared to the females. The mass of the SC fat layer was the best predictor for total fat mass (R 2 = 0.98) and percent body fat (R 2 = 0.89) when using simple regressions. As this depot can be laborious and difficult to remove with consistency, the omental fat mass could be also used as a predictor for total fat mass (R 2 = 0.70) and percent body fat (R 2 = 0.42) in juveniles and the retroperitoneal fat mass in subadults/adults (R 2 = 0.80 and 0.79, respectively). We also evaluated the different fat depots using the part-whole methodology by removing the mass of the fat depot of interest from the dependent variable. According to the part-whole regressions, the masses of the omental (R 2 = 0.66) and mesenteric depots (R 2 = 0.56) were the best predictors for total fat mass in the juveniles and the masses of the retroperitoneal (R 2 = 0.78) and diaphragmatic depots (R 2 = 0.77) in the subadults/adults. Based on both simple and part-whole regressions, omental fat can be suggested as a predictor for total fat mass in juvenile mink and retroperitoneal fat in subadult/adult mink due to their relatively good predictive power and ease of dissection.

Effect of temperament and behavioural reactions to the presence of a human during the pre-mating period on reproductive performance in farmed mink (Mustela vison)

The present study sought to evaluate the relationship between temperament, pre-mating behaviour and reproductive performance in farmed female mink (Mustela vison). Temperament was measured by using a stick test and behavioural reactions to the presence of a human during pre-mating period by a walking test. The experimental animals comprised 100 confident and 100 fearful scanblack female mink. In each temperament group, 58% of female mink were primiparous and 42% were multiparous. The length and timing of mating periods and the length of the gestation period were similar in all groups. Pooled data showed that the length of the gestation period correlated negatively with litter size (r = -0.17, P = 0.03). The whelping proportions for confident and fearful primiparous female mink were 81% and 74% (P = 0.37), respectively, and for multiparous females 83% and 81% (P = 0.78), respectively. The number of kits per mated and whelped female at parturition (P < 0.01 and P = 0.04, respectively) and at weaning (P < 0.01 and P = 0.07, respectively) was significantly higher in confident than in fearful females. A significant correlation between kit losses and litter size was found only in primiparous and multiparous confident females (r = 0.35, P = 0.02; r = 0.32, P = 0.07). Postnatal kit mortality was higher in primiparous confident females than fearful females. During walking tests, fearful animals, irrespective of age, remained in side the nest box more frequently than did confident ones. Stationary behaviour outside the cage (lying, sitting, standing, etc.) was more common in confident than in fearful animals (P < 0.001). Significant differences in locomotor activity or stereotypies were not found between the groups. In multiparous fearful females, the whelping result declined significantly with the increasing incidence of stereotypies (r = -0.37, P = 0.04). In primiparous fearful female mink, the relationship was the reverse (r = 0.37; P = 0.01). We conclude that the significant temperament dichotomy (confident vs. fearful) found in farmed mink stock has a marked effect on the reproductive performance of this species. Key words: Farm-bred mink, personality trait, temperament, reproductive performance, domestication