本试验旨在研究低蛋白质饲粮中添加蛋氨酸对冬毛期蓝狐生产性能、营养物质消化率及氮代谢的影响。选用25周龄健康雄性蓝狐105只，平均体重为（4.88±0.60）kg，随机分为7组，每组15个重复，每个重复1只。正对照组饲喂蛋白质水平为28%的基础饲粮，负对照组饲喂蛋白质水平为26%的基础饲粮，试验组分别饲喂在低蛋白质饲粮（蛋白质水平为26％的基础饲粮）基础上添加0.2%、0.4%、0.6%、0.8%和1.0%蛋氨酸的试验饲粮。预试期7 d，正试期80 d。结果表明：0.6%蛋氨酸组终末体重、平均日增重和饲料转化率极显著高于负对照组和0.2%蛋氨酸组（P<0.01），并且饲料转化率显著高于0.4%、0.8%、1.0%蛋氨酸组和正对照组（P<0.05）；0.6%蛋氨酸组干皮长显著长于0.2%、0.4%、0.8%蛋氨酸组和负对照组（P<0.05），并与正对照组差异不显著（P>0.05）。0.6%蛋氨酸组干物质消化率、粗蛋白质消化率及粗脂肪消化率与正对照组相比差异不显著（P>0.05），但显著或极显著高于负对照组（P<0.05或P<0.01）；1.0%蛋氨酸组半胱氨酸消化率和蛋氨酸消化率显著或极显著高于其他各组（P<0.05或P<0.01）。0.6%蛋氨酸组氮沉积极显著高于0.2%、0.4%、1.0%蛋氨酸组及负对照组（P<0.01），与正对照组相比差异不显著（P>0.05）；0.6%蛋氨酸组净蛋白质利用率和蛋白质生物学价值显著高于1.0%蛋氨酸组和负对照组（P<0.05），与正对照组相比差异不显著（P>0.05）。综合本试验各项测定指标，在蛋白质水平为26%的低蛋白质饲粮中添加0.6%的蛋氨酸，即饲粮中蛋氨酸水平为0.99%时，能够满足冬毛期蓝狐对蛋氨酸的需要量，此时蓝狐的生长性能、营养物质消化率、氮沉积和相应的毛皮参数较为理想。

This experiment was conducted to study the effects of methionine supplementation in low-protein diets on performance, nutrient digestibility and nitrogen metabolism of blue foxes during the winter hair period. One hundred and five healthy male blue foxes at the age of 25 weeks with an average body weight of (4.88±0.60) kg were randomly assigned into 7 groups with 15 replicates per group and 1 fox per replicate. The blue foxes in positive control group were fed a 28% protein level basal diet, and those in negative control group were fed a 26% protein level basal diet. The blue foxes in experimental groups were fed low-protein diets (26% protein level basal diets) supplemented with 0.2%, 0.4%, 0.6%, 0.8% and 1.0% methionine, respectively. The pre-test lasted for 7 days and the formal test lasted for 80 days. The results showed as follows: the final body weight, average daily gain and feed conversion rate in 0.6% methionine group were extremely significantly higher than those in negative control group and 0.2% methionine group (P<0.01), and the feed conversion rate was significantly higher than that in 0.4%, 0.8% and 1.0% methionine groups and positive control group (P<0.05). The length of dry fur in 0.6% methionine group was not significantly different compared with positive control group (P>0.05), but significantly longer than that in 0.2%, 0.4% and 0.8% methionine groups and positive control group (P<0.05). The digestibility of dry matter, crude protein and ether extract in 0.6% methionine group was not significantly different compared with positive control group (P>0.05), but significantly or extremely significantly higher than that in negative control group (P<0.05 or P<0.01); the digestibility of cysteine and methionine in 1.0% methionine group was significantly or extremely significantly higher than that in other groups (P<0.05 or P<0.01). The nitrogen deposition in 0.6% methionine group was not significantly different compared with positive control group (P>0.05), but extremely significantly higher than that in 0.2%, 0.4% and 1.0% methionine groups and negative control group (P<0.01); the net protein utilization and protein biological value in 0.6% methionine group were not significantly different compared with positive control group (P>0.05), but significantly higher than those in 1.0% methionine group and negative control group (P<0.05). In conclusion, considering all measured indices of this experiment, when 0.6% methionine is supplemented in the low-protein diet with 26% protein level, that is, when the dietary methionine level is 0.99%, methionine requirement of blue foxes during the winter hair period can be met. In this case, the blue foxes have the optimum growth performance, nutrient digestibility, nitrogen deposition and relevant fur parameters.