饲粮色氨酸添加水平对育成期白水貂生长性能、氮代谢及氨基酸消化率的影响

本试验旨在研究饲粮色氨酸添加水平对育成期白水貂生长性能、氮代谢及氨基酸消化率的影响。选取60只健康、体重(0.83±0.09)kg]相近的(60±5)日龄雄性白水貂,随机分成6个组,每组10个重复,每个重复1只水貂。负对照组(Ⅰ组)饲喂粗蛋白质水平为34%的基础饲粮(色氨酸水平为0.22%),试验组分别饲喂在负对照组基础饲粮中添加0.1%(Ⅱ组)、0.3%(Ⅲ组)、0.5%(Ⅳ组)和0.7%色氨酸(Ⅴ组)的试验饲粮,正对照组(Ⅵ组)饲喂粗蛋白质水平为36%的基础饲粮(色氨酸水平为0.22%)。预试期7 d,正试期60 d。结果表明:1)各组水貂60~120日龄平均日增重和平均日采食量差异不显著(P0.05),Ⅲ组、Ⅳ组、Ⅵ组平均日增重略高于其他各组。2)Ⅰ组干物质消化率显著高于Ⅱ组、Ⅲ组、Ⅳ组、Ⅵ组(P0.05)。Ⅴ组、Ⅵ组粗脂肪消化率显著高于Ⅳ组(P0.05)。Ⅳ组、Ⅴ组、Ⅵ组尿氮显著高于Ⅲ组(P0.05)。Ⅰ组、Ⅲ组氮沉积显著高于Ⅳ组(P0.05)。Ⅲ组净蛋白质利用率和蛋白质生物学价值显著高于Ⅳ组、Ⅴ组、Ⅵ组(P0.05)。3)Ⅰ组谷氨酸、苯丙氨酸、赖氨酸、脯氨酸消化率显著高于Ⅲ组(P0.05)。Ⅰ组、Ⅵ组异亮氨酸消化率显著高于Ⅲ组(P0.05)。Ⅰ组、Ⅵ组亮氨酸消化率显著高于Ⅲ组(P0.05)。Ⅴ组丙氨酸消化率显著高于Ⅲ组(P0.05)。Ⅵ组蛋氨酸消化率显著高于其他各组(P0.05),Ⅰ组、Ⅳ组、Ⅴ组蛋氨酸消化率显著高于Ⅱ组、Ⅲ组(P0.05)。Ⅰ组、Ⅴ组、Ⅵ组酪氨酸消化率显著高于Ⅲ组、Ⅳ组(P0.05)。Ⅰ组、Ⅴ组、Ⅵ组半胱氨酸消化率显著高于Ⅳ组(P0.05)。Ⅴ组组氨酸消化率显著高于Ⅱ组、Ⅲ组(P0.05)。Ⅰ组、Ⅲ组、Ⅵ组色氨酸消化率显著高于Ⅱ组(P0.05)。Ⅰ组、Ⅴ组、Ⅵ组精氨酸消化率显著高于Ⅱ组、Ⅲ组(P0.05)。Ⅰ组总氨基酸消化率显著高于Ⅲ组(P0.05)。由此得出,综合生长性能、氮代谢及氨基酸消化率指标,饲粮粗蛋白质水平为34%时,水貂饲粮色氨酸适宜添加水平为0.3%(饲粮色氨酸水平为0.52%)。

Effects of Dietary Tryptophan Supplemental Level on Growth Performance,Nitrogen Metabolism and Amino Acid Digestibility of White Minks during Growing Period

This study was conducted to study the effects of dietary tryptophan ( Trp ) supplemental level on growth performance, nitrogen metabolism and amino acid digestibility of white minks during growing period. Sixty healthy male white minks at the age of 60 days with similar body weight (0.83±0.09) kg] were ran-domly divided into 6 groups with 10 replicates per group and 1 mink per replicate. Minks in the negative control group ( group Ⅰ) were fed a basal diet ( crude protein level was 34%, Trp level was 0.22%) , minks in the experimental groups were fed the basal diets supplemented with 0.1% ( group Ⅱ) , 0.3% ( group Ⅲ) , 0.5%( group Ⅳ) , 0.7% Trp ( group Ⅴ) , respectively, and minks in the positive control group ( group Ⅵ) were fed a basal diet ( crude protein level was 36%, Trp level was 0.22%) . The pretest period lasted for 7 days and the trial lasted for 60 days. The results showed as follows:1) the average daily gain and average daily feed in-take of minks during 60 to 120 days of age had no significant difference among all groups ( P>0.05) , the av-erage daily gain of groups Ⅲ, Ⅳ, Ⅵ was higher than that of other groups. 2) The dry matter digestibility of group Ⅰ was significantly higher than that of groups Ⅱ, Ⅲ, Ⅳ and Ⅵ ( P<0.05) . The ether extract digesti-bility of groups Ⅴ and Ⅵ was significantly higher than that of group Ⅳ (P<0.05). The urine nitrogen of groups Ⅳ, Ⅴ and Ⅵ was significantly higher than that of group Ⅲ (P<0.05). The nitrogen deposition of groupsⅠ andⅢ was significantly higher than that of groupⅣ ( P<0.05) . The net protein utilization and bio-logical value of protein of group Ⅲ was significantly higher than that of groups Ⅳ, Ⅴ and Ⅵ ( P<0.05) . 3) The digestibilities of glutamate, phenylalanine, lysine and proline of group Ⅰ were significantly higher than those of groupⅢ( P<0.05) . The isoleucine digestibility of groupsⅠandⅥwas significantly higher than that of groupⅢ( P<0.05) . The leucine digestibility of groupsⅠandⅥwas significantly higher than that of groupⅢ ( P<0.05) . The alanine digestibility of group Ⅴ was significantly higher than that of group Ⅲ ( P<0.05) . The methionine digestibility of group Ⅵ was significantly higher than that of other groups ( P<0.05) , and the methionine digestibility of groups Ⅰ, Ⅳ and Ⅴ was significantly higher than that of groups Ⅱ and Ⅲ ( P<0.05). The tyrosine digestibility of groupsⅠ,ⅤandⅥwas significantly higher than that of groupsⅢandⅣ( P<0.05) . The cysteine digestibility of groups Ⅰ, Ⅴ and Ⅵ was significantly higher than that of groups Ⅳ( P<0.05) . The histidine digestibility of group Ⅴ was significantly higher than that of groups Ⅱ and Ⅲ ( P<0.05). The Trp digestibility of groupsⅠ,ⅢandⅥwas significantly higher than that of groupⅡ(P<0.05). The arginine digestibility of groups Ⅰ,Ⅴ and Ⅵ was significantly higher than that of groups Ⅱ and Ⅲ ( P<0.05). The total amino acid digestibility of groupⅠwas significantly higher than that of groupⅢ(P<0.05). In conclusion, comprehensive considers the growth performance, nitrogen metabolism and amino acid digesti-bility indices, when dietary crude protein level is 34%, the dietary suitable Trp supplemental level for minks is 0.3% (dietary Trp level is 0.52%).