Effects of different dietary manganese levels on growth performance and N balance of growing mink (Neovision vision).

Two experiments were conducted to study the effects of dietary manganese levels on growth performance, nutrients digestibility, and N balance of minks during growing period. In experiment 1, 75 healthy male minks (60 days old) were selected and randomly divided into five groups with different types of diet. The diet was supplemented with 0 (control), 50, 100, 300, and 600 ppm of manganese as MnSO4 of dry matter (DM) in basic diet, respectively. From early July to middle September, the results showed that the final body weights of minks were significantly affected by diets (P < 0.05). Average daily gains (ADG) were significantly higher in the 300-ppm manganese group than those in other groups. The ratio of feed to body weight gain (F/G) was significantly affected by manganese level (P < 0.05). In experiment 2, 45 male minks (75 days old) with the same body weight were selected from each group of experiment 1 to carry out the nutrient digestion and N-balance tests which lasted for 4 days for the collection of the feces and urine, and the diets and treatment codes were same as in experiment 1. The results showed that no significant differences were found in DM, crude protein (CP), and crude carbohydrate (CC) digestibility among all groups (P > 0.05), but ether extract (EE) and gross energy (GE) digestibility were all the highest in the 300-ppm group. N intake and fecal N were similar among all groups (P > 0.05). Urinary N was lower in the 300-ppm group; in contrast, N retention was higher in this group (P < 0.05). In conclusion of experiment 1 and experiment 2, the diet supplemented with 300 ppm of manganese (as manganese sulfate) could improve the growth performance and increase the EE and GE digestibility of mink during the growing period and moreover reduce the nitrogen emissions to the environment, and the optimal total manganese level in mink's diet was 409.16 in DM during the growing period.