Abstract: The experiment was conducted to evaluate the regularity of digestibility and metabolism of diets with different levels in female minks on preparative mating period. 180 healthy female minks of one year and a half old were randomly assigned into six groups with 30 replicates and each replicate had 1 mink. The treatments were individually fed with 28.59%(group Ⅰ),32.31%(group Ⅱ),36.21%(group Ⅲ),40.35%(group Ⅳ) protein levels in fresh feed diets and with 32.66%(group Ⅴ),40.47%(group Ⅵ) protein levels in mixed feed diets. The period of trial lasted for 51 days,including 7 days preset period and 44 days test period. The results showed that the food intake of the fresh feed diets groups was higher than that of the mixed feed diets group,some had significantly difference(P<0.05). On the item of the digestibility of dry mater,protein and fat,some had significantly difference (P<0.05).The nitrogen intake, fecal nitrogen, urine nitrogen increased with the protein level in different groups. There was no significantly difference in nitrogen retention, the biology value of protein, net protein usage ratio. However, all of the three indexes tended to decrease when the dietary protein level reached 36.21%. Of all the indexes, the mixed feed diets group were significantly or extremely lower than the fresh feed diets group(P<0.05 or P<0.01). In conclusion, the minks had almost equally best nutrient digestibility and availability when the dietary protein level reached 32.31% and 36.21%, but in consideration of the feed expense and the particular characteristics of the preparative mating minks, 32.31% protein level of diet would be the best choice in the preparative mating period, and the mixed feed diets were not recommended for this particular period.

Key words: diet; protein; preparative mating period; mink; digestibility; nitrogen metabolism