本试验旨在研究饲粮色氨酸水平对生长獭兔生长性能、氮代谢、血清生化指标及毛皮质量的影响。试验选用断奶獭兔200只,随机分为5组(每组40个重复,每个重复1只),分别饲喂色氨酸实测水平为0.086%、0.135%、0.176%、0.218%和0.268%的试验饲粮。预试期7 d,正试期53 d。结果表明:在初始体重无显著差异(P>0.05)的情况下,饲粮色氨酸水平对平均日增重、平均日采食量和料重比均无显著影响(P>0.05),但以饲粮色氨酸水平为0.176%时料重比最低。饲粮色氨酸水平极显著影响粪氮(P=0.000 6)和氮表观消化率(P=0.002 0),显著影响食入氮(P=0.032 0)和氮生物学价值(P=0.014 8),而对尿氮、可消化氮、沉积氮和氮沉积率无显著影响(P>0.05)。饲粮色氨酸水平为0.218%的组的氮生物学价值最高,显著高于饲粮色氨酸水平为0.086%和0.268%的组(P<0.05)。饲粮色氨酸水平极显著影响血清尿素氮含量(P=0.000 5),显著影响血清甘油三酯(P=0.045 7)和胆固醇含量(P=0.040 6),而对血清谷丙转氨酶活性无显著影响(P>0.05)。在毛皮面积无显著差异(P>0.05)的情况下,饲粮色氨酸水平显著影响毛皮重量(P=0.010 8),其中饲粮色氨酸水平为0.176%和0.218%的组显著高于饲粮色氨酸水平为0.086%和0.135%的组。饲粮色氨酸水平对毛皮中成纤维细胞生长因子5(FGF5)mRNA表达量无显著影响(P>0.05),但以饲粮色氨酸水平为0.218%时最高。综合本试验测定指标,生长獭兔饲粮适宜的色氨酸水平为0.176%～0.218%。

This experiment was conducted to study the effects of dietary tryptophan level on growth performance, nitrogen metabolism, serum biochemical indices and fur quality of growing Rex rabbits. Two hundred weaner Rex rabbits were randomly assigned to 5 groups with 40 replicates in each group and each replicate contained 1 rabbit. Rabbits in the 5 groups were fed experimental diets with the measured levels of 0.086%, 0.135%, 0.176%, 0.218% and 0.268% tryptophan, respectively. The trial lasted for 7 days for adaptation and 53 days for test. The results showed as follows: under the condition of no significant difference in initial body weight (P>0.05), dietary tryptophan level did not significantly affect the average daily feed intake (ADFI), average daily gain (ADG) and feed/gain (F/G) (P>0.05), but the group with the diet containing 0.176% tryptophan had the lowest F/G. Dietary tryptophan level had significant effects on fecal nitrogen (P=0.000 6), nitrogen apparent digestibility (P=0.002 0), nitrogen intake (P=0.032 0) and biological value of nitrogen (P=0. 014 8), but had no significant effects on urine nitrogen, digestible nitrogen, retention nitrogen and nitrogen retention rate (P>0.05). The biological value of nitrogen in the group with the diet containing 0.218% tryptophan had the highest value, and was significantly higher than that in the groups with the diets containing 0.086% and 0.286% tryptophan (P<0.05). Dietary tryptophan level had significant effects on the contents of serum urea nitrogen (P=0.000 5), cholesterol (P=0.040 6) and triglycerides (P=0.045 7), but had no significant effect on serum alanine aminotransferase activity (P>0.05). Dietary tryptophan level had no significant effect on fur area, but had a significant effect on fur weight (P=0.010 8), and that in the groups with the diets containing 0.176% and 0.218% tryptophan was significantly higher than that in the groups with the diets containing 0.086% and 0.135% tryptophan (P<0.05). Dietary tryptophan level had no significant effect on fibroblast growth factor 5 (FGF5) mRNA expression level, but the group with the diet containing 0.218% tryptophan had the highest FGF5 mRNA expression level. Considering all indices of this experiment, the appropriate tryptophan levels in the diet of growing Rex rabbits are 0.176% to 0.218%.