本试验旨在研究低蛋白质饲粮中添加尿素对肉兔生长发育与血液指标的影响。采用单因子随机区组试验设计,选择120只50日龄、体重相近的健康新西兰兔,随机分为4组,1个对照组和3个试验组,每组15个重复,每个重复2只。对照组饲喂粗蛋白质含量为11.11%的基础饲粮,3个试验组分别饲喂在基础饲粮中以糊化淀粉缓释尿素的方式添加1%、2%和3%尿素的试验饲粮。预试期为10 d,正试期为30 d。结果表明:试验第2天,3%尿素组80%试验兔因发生氨中毒而死亡。1%尿素组试验兔末重、增重和日增重均极显著高于对照组和2%尿素组(P<0.01)。与对照组相比,1%和2%尿素组试验兔全血氨氮含量、血清谷丙转氨酶活性显著或极显著升高(P<0.05或P<0.01),而肝脏重和系数则显著或极显著降低(P<0.05或P<0.01)。2%尿素组试验兔日干物质进食量、胴体重和屠宰率均极显著低于对照组和1%尿素组(P<0.01),而料重比则极显著高于对照组和1%尿素组(P<0.01)。2%尿素组试验兔血清尿素氮含量以及谷草转氨酶、碱性磷酸酶活性均极显著高于对照组和1%尿素组(P<0.01)。2%尿素组试验兔心脏、脾脏和肾脏重均显著低于对照组和1%尿素组(P<0.05),而肾脏系数则极显著高于对照组和1%尿素组(P<0.01)。2%尿素组试验兔胃重、十二指肠重与长、空肠重与长、回肠重与长、盲肠重与系数、蚓突重与系数及长、大肠重与长显著或极显著低于对照组和1%尿素组(P<0.05或P<0.01),且回肠系数及盲肠长显著或极显著低于对照组(P<0.05或P<0.01)。由此得出,低蛋白质饲粮中添加3%的尿素会造成肉兔氨中毒死亡;添加2%的尿素会使肉兔生长发育停滞;添加1%的尿素可改善肉兔育肥性能,但会对肝脏的发育产生不利影响。

The aim of this study was to investigate the effects of urea supplementation in a low protein diet on growth and development and blood indices of meat rabbits. A single factor randomized block design was used in the experiment. One hundred and twenty New Zealand rabbits at 50 days of age with the similar body weight were randomly allotted into 4 groups with 15 replicates per group and 2 rabbits per replicate. One group was the control group and the rest groups were the experimental groups. The rabbits in the control group were fed a basal diet with 11.11% crude protein, and the rabbits in the 3 experimental groups were fed the basal diets supplemented with 1%, 2% and 3% urea by the way of the starea, respectively. The duration of the preliminary experiment was 10 d and the duration of the formal experiment was 30 d. The results showed as follows: on the second day of the experiment, 80% of rabbits in 3% urea group were dead because of ammonia poisoning.The final weight, weight gain and average daily gain of rabbits in 1% urea group were significantly higher than those in the control group and 2% urea group (P<0.01). Compared with the control group, the whole blood ammonia nitrogen content and serum glutamic pyruvict ransaminase activity of rabbits in 1% and 2% urea groups were significantly increased (P<0.05 or P<0.01), while the liver weight and coefficient were significantly decreased (P<0.05 or P<0.01). Compared with the control group and 1% urea group, the dry matter daily intake, carcass weight and dressing percentage of rabbits in 2% urea group were significantly decreased (P<0.01), while the ratio of feed to gain was significantly increased (P<0.01). The urea nitrogen content and activities of glutamic-oxalacetic transaminase and alkaline phosphatase in serum of rabbits in 2% urea group were significantly higher than those in the control group and 1% urea group (P<0.01). Compared with the control group and 1% urea group, the weight of heart, spleen and kidney of rabbits in 2% urea group were significantly decreased (P<0.05), while the kidney coefficient was significantly increased (P<0.01). The stomach weight, duodenum weight and length, jejunum weight and length, caecum weight and coefficient, appendix weight, coefficient and length, large intestine weight and length of rabbits in 2% urea group were significantly lower than those in control group and 1% urea group (P<0.05 or P<0.01), and the ileum coefficient and caecum length were significantly lower than those in the control group (P<0.05 or P<0.01). In conclusion, low protein diet supplemented with 3% urea can cause the death of the meat rabbits because of ammonia poisoning, 2% urea can cause the stagnancy of growth and development, and 1% urea can improve the growth and finishing performance, but has a negative effect on the development of liver.