Effect of dietary vitamin A supplementation on growth performance, nutrient digestibility, serum parameters and liver histology of growing-furring male mink kits (Neovison vison)

Abstract

This experiment was conducted to investigate the effects of supplemental vitamin A (VitA) on the growth performance, nutrient digestibility, serum biochemical parameters, and liver histology of growing-furring mink kits (Neovison vison). Ninety healthy male mink were randomly assigned to 6 treatment groups, with 15 mink per group. Each mink was housed in an individual cage. Mink in the 6 groups were fed diets supplemented with vitamin A acetate at dosages of 0 kIU/kg (VitA 0), 5 kIU/kg (VitA5), 20 kIU/kg (VitA20), 80 kIU/kg (VitA80), 320 kIU/kg (VitA320) or 1280 kIU/kg (VitA1280) of the basal diet. A 7-day pretest period preceded a formal test period of 60 days. The results showed that the final body weight (BW), average daily gain (ADG), weight gain (WG), average daily feed intake (ADFI) and the digestibility of dry matter (DM), crude protein (CP), ether extract (EE), and carbohydrate (CHO) exhibited a quadratic relationship (P < 0.05) to the dosage of dietary vitamin A; the highest values were observed in the VitA20 group. Metabolizable energy intake (ME intake) was significantly affected by increasing dietary vitamin A (linear and quadratic, P < 0.05). The serum concentrations of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and alkaline phosphatase (ALP) showed a quadratic relationship (P < 0.05) with vitamin A intake; the lowest values were observed in the VitA20 group. The serum concentrations of triglycerides (TGs) were significantly affected by increasing dietary vitamin A (linear, P < 0.05; quadratic, P < 0.05). The serum concentrations of total protein (TP), albumin (ALB), high-density lipoprotein cholesterol (HDL-C), lactic dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were increased linearly (P < 0.05). Increasing vitamin A addition did not affect the concentration of retinol in serum but clearly affected the concentration of retinol in liver (P < 0.05). Prominent lipid vacuoles were observed in the liver tissue sections of mink in the VitA0 and VitA1280 groups. We concluded that the supplementation of diets with vitamin A at doses of 20–80 kIU/kg could improve growth and that a vitamin-A-supplemented diet could help reduce the severity of hepatic lipidosis in mink; however, excess vitamin A may negatively affect growth and lipid metabolism. Future research is needed to determine the mechanisms underlying the effects of vitamin A supplementation on the growth of mink.