Absorption of α-tocopheryl acetate is limited in mink kits (Mustela vison) during weaning

Bioavailability of α-tocopherol varies with source, dose and duration of supplementation. The effect of source and dose of α-tocopherol on response of α-tocopherol stereoisomers in plasma and tissues of mink kits during the weaning period was studied. Twelve mink kits were euthanised in CO2 at the beginning of the experiment, and 156 mink kits (12 replicates per treatment group) were randomly assigned to thirteen treatment groups: no added α-tocopherol in the feed (0 dose) or four different doses (50, 75, 100 and 150 mg/kg of diet) of RRR-α-tocopherol (ALC), RRR-α-tocopheryl acetate (ACT) or all-rac-α-tocopheryl acetate (SYN). Six mink kits per treatment group were euthanised 3 weeks after initiation of the experiment, and the remaining six were euthanised 6 weeks after initiation of the experiment. The RRR-α-tocopherol content in plasma, liver, heart and lungs was affected by interaction between source and dose (P < 0.01 for all). The highest RRR-α-tocopherol content in plasma (13.6 µg/ml; LS-means for source across dose and week), liver (13.6 µg/mg), heart (7.6 µg/mg) and lungs (9.8 µg/mg) was observed in mink kits fed ALC. The RRR-α-tocopherol content in plasma and tissues depended on source and dose interaction and increased linearly with supplementation. In conclusion, the interaction between source and dose reveals a limitation in hydrolysis of ester bond in α-tocopheryl acetate in mink kits around weaning as the likely causative explanation for the higher response of ALC at the highest doses. Thus, considerable attention has to be paid to the source of α-tocopherol during weaning of mink kits fed a high dose of α-tocopherol.

Effects of calcium, phosphorus, and vitamin D on growing mink (Mustela vison)

The present study investigated the effects of dietary calcium (Ca), phosphorus (P), and vitamin D (VD) supplements on growth performance, Ca:P digestion and metabolism, and serum biochemical indexes of growing male mink (Mustela vison) under conditions of a fixed 2:1 ratio of Ca to P. About 135 dark male mink were randomly assigned to nine groups. The experiment was conducted with a 3 × 3 (Ca:P × VD) factorial design using a corn–fish meal-based diet that contained 2.3% Ca, 1.15% P, and 2100 IU kg−1 VD. The supplementary Ca and P levels were 0%:0%, 0.4%:0.2%, and 0.8%:0.4% of the diets, respectively, whereas supplementary VD levels were 0, 2000, and 4000 IU kg−1. The Ca and P dosage had a significant effect on growth performance of the mink (P < 0.05). The appropriate VD level, which was 4100 IU kg−1, significantly improved protein utilization and Ca and P digestibility of growing mink (P < 0.05). In addition, excreta pollution to the environment was also significantly reduced (P < 0.05). In conclusion, Ca:P (3.1%:1.55%) and VD (4100 IU kg−1) had an important effect on growth performance and protein utilization in growing mink and could reduce environmental pollution by improving protein and P utilization.

Distribution of α-tocopherol stereoisomers in mink (Mustela vison) organs varies with the amount of all-rac-α-tocopheryl acetate in the diet

Synthetic α-tocopherol has eight isomeric configurations including four 2R (RSS, RRS, RSR, RRR) and four 2S (SRR, SSR, SRS, SSS). Only the RRR stereoisomer is naturally synthesised by plants. A ratio of 1·36:1 in biopotency of RRR-α-tocopheryl acetate to all-rac-α-tocopheryl acetate is generally accepted; however, studies indicate that neither biopotency of α-tocopherol stereoisomers nor bioavailability between them is constant, but depend on dose, time, animal species and organs. A total of forty growing young male mink were, after weaning, assigned one of the following treatments for 90 d: no α-tocopherol in diet (ALFA_0), 40 mg/kg RRR-α-tocopheryl acetate (NAT_40), 40 mg/kg all-rac-α-tocopheryl acetate (SYN_40) and 80 mg/kg feed all-rac-α-tocopheryl acetate (SYN_80). Mink were euthanised in CO2 and blood was collected by heart puncture. Mink were pelted and liver, heart, lungs, brain and abdominal fat were collected for α-tocopherol stereoisomer analysis. The proportion of RRR-α-tocopherol decreased in all organs and plasma with increasing amount of synthetic α-tocopherol stereoisomers in the diet (P≤0·05), whereas the proportion of all synthetic α-tocopherol stereoisomers increased with increasing amount of synthetic α-tocopherol stereoisomers in the diet (P≤0·05). The proportion of α-tocopherol stereoisomers in plasma, brain, heart, lungs and abdominal fat showed the following order: RRR>RRS, RSR, RSS>Σ2S, regardless of α-tocopherol supplement. The liver had the highest proportion of Σ2S stereoisomers, and lowest proportion of RRR-α-tocopherol. In conclusion, distribution of α-tocopherol stereoisomers differs with dose and form of α-tocopherol supplementation. The results did also reveal the liver’s role as the major organ for accumulation of Σ2S α-tocopherol stereoisomers.