准备配种期雌性蓝狐对不同蛋白质水平日粮营养物质消化率及氮代谢的比较研究

试验旨在研究准备配种期母狐对不同蛋白质水平日粮的消化代谢规律。选择健康母狐180只，随机分成4组，每组45个重复，每个重复1只。各组母狐分别饲喂蛋白质水平为21.64%（Ⅰ组）、26.21%（Ⅱ组）、30.43%（Ⅲ组）和35.10%（Ⅳ组）的日粮。预试期7 d，正试期45 d。结果表明，蛋白质消化率、干物质排出量、粪氮代谢的影响差异不显著，Ⅲ组和Ⅳ组的干物质采食量显著或极显著高于Ⅰ组和Ⅱ组（P<0.05或P<0.01），Ⅲ组的脂肪消化率显著或极显著高于Ⅰ、Ⅱ和Ⅳ组（P<0.05或P<0.01），Ⅳ组氮沉积极显著低于Ⅰ、Ⅱ和Ⅲ组（P<0.01）。随着饲料蛋白质水平的增加，食入氮和尿氮随之提高（P<0.05或P<0.01），净蛋白利用率、蛋白质生物学价值逐渐降低（P<0.05或P<0.01）。由此得知，当蛋白质水平为30.43%时，各种营养物质消化率最为理想，但21.64%的蛋白质水平足以满足准备配种期雌性蓝狐的蛋白质需要，且蛋白质的利用率达到最高。

Comparative Research on Nitrogen Metabolize and Nutrient Matter Digestibility of Diets with Different Protein Levels in Female Blue Foxes in Prepare Breeding Period

The experiment was conducted to study the regularity of digestibility and metabolism of diets with different protein levels in fox at prepare breeding period. 180 blue foxes were randomly divided into 4 groups with 45 replicates and each replicate had 1 fox. The foxes in 4 groups were fed with protein levels of 21.64% (group Ⅰ), 26.21% (group Ⅱ),30.43% (group Ⅲ) and 35.10% (group Ⅳ), respectively. The experiment lasted for 52 days, including preset period for 7 days and test period for 45 days. The results showed as follows: foxes in different groups had no significant difference in dry matter output, protein digestibility, fecal nitrogen (P>0.05); dry matter intake in groups Ⅲ and Ⅳ was significant higher than that in groups Ⅰ and Ⅱ （P<0.05 or P<0.01）; the digestibility of fat in group Ⅲ was significant higher than that in groups Ⅰ, Ⅱ and Ⅳ （P<0.05 or P<0.01）; the nitrogen retention in group Ⅳ was significant lower than that in groups Ⅰ, Ⅱ and Ⅲ（P<0.01）. With the increase of dietary protein levels, nitrogen intake and urine nitrogen were increased (P<0.05 or P<0.01), net protein utilization and biological value of protein gradually decreased (P<0.05 or P<0.01). In conclusion, when the protein level of diet arrived at 30.43%, the nutrient digestibility was optimal, but the diet of 21.64% protein level can satisfy the protein need of the fox at prepare breeding period, and CP utilization efficiency is highest.