本试验旨在研究降低日粮赖氨酸净能比（Lys/NE）对育肥猪生产性能及肉品质的影响。选用140头（30.0±1.6）kg大白猪，按体重相近，性别比例一致原则随机分到5个处理，每个处理4个重复，每个重复7头猪。在30～61 kg阶段所有猪饲喂相同日粮，随后的育肥阶段各处理分别饲喂5种处理日粮：对照、低赖氨酸-1、低赖氨酸-2、低蛋白质-1和低蛋白质-2（粗蛋白质水平分别为15.20%、15.02%、15.11%、12.73%和10.10%；Lys/NE分别为0.72、0.58、0.46、0.58和0.46 g/MJ）。结果表明，与对照相比，低赖氨酸-1和低赖氨酸-2处理可显著提高育肥猪平均日增重和肌内脂肪含量（P<0.05），但同时降低粗蛋白质水平对平均日增重和肌内脂肪含量没有显著影响（P>0.05）。各处理间日均采食量、料重比、宰前活重、屠宰率、pH1 h、pH24 h、剪切力和滴水损失差异均不显著（P>0.05）。与对照相比，低赖氨酸-2和低蛋白质-2处理显著降低肉色值（P<0.05）。除低蛋白质-2处理的育肥猪血浆尿素氮含量显著低于对照外（P<0.05），其他各处理间血浆尿素氮含量差异不显著（P>0.05）。与对照相比，低赖氨酸-1和低赖氨酸-2处理的血浆类胰岛素生长因子-Ⅰ含量显著降低（P<0.05），而低蛋白质-1和低蛋白质-2处理的血浆类胰岛素生长因子-Ⅰ含量显著提高（P<0.05）。结果提示，育肥猪日粮Lys/NE由0.72 g/MJ降至0.46 g/MJ可显著提高猪肉肌内脂肪含量；育肥猪日粮Lys/NE降至0.46 g/MJ时，若同时降低日粮蛋白质水平至10.10%，则会降低育肥猪的饲料转化效率。

This experiment was conducted to determine the effects of reducing the ratio of dietary lysine (Lys) to net energy (Lys/NE) on performance and meat quality in finishing pigs. One hundred and forty Yorkshire pigs with initial average body weight of (30.0±1.6) kg were randomly allotted to 5 treatments (4 replicates per treatment and 7 pigs per replicate) based on their body weight and sex. During the 30～61 kg phase, all pigs were fed the same diet. During the finishing phase, pigs in each treatment were randomly fed with one of five diets: control, low Lys-1, low Lys-2, low protein-1 and low protein-2 (CP levels were 15.20%, 15.02%, 15.11%, 12.73% and 10.10%, respectively; Lys/NE ratios were 0.72, 0.58, 0.46, 0.58 and 0.46 g/MJ, respectively). The results showed that the low Lys-1 and low Lys-2 treatments had significantly increased average daily gain (ADG) and intramuscular fat (IMF) content of pork in finishing pigs (P<0.05) compared with control, but simultaneous decrease of CP level had no significant difference on ADG and IMF of pork compared with control (P>0.05). Different treatments had no significant effect on average daily feed intake, F/G, alive weight, dressing percentage, pH1 h, pH24 h, shear force and drip loss (P>0.05). Low Lys-2 and low CP-2 treatments had lower meat color value than control diet (P<0.05). No significant effects on plasma urea nitrogen (PUN) content were observed among other treatments (P>0.05), except that plasma UN content in low protein-2 treatment was significantly lower than that in control (P<0.05). Compared with control, pigs fed the low Lys-1 and low Lys-2 diets had lower plasma IGF-Ⅰ content (P<0.05), while pigs fed low protein-1 and low protein-2 diets had higher plasma IGF-Ⅰ content (P<0.05). The results indicated that Lys/NE in diet decrease from 0.72 to 0.46 g/MJ could improve IMF content of finishing pigs; Lys/NE in diet reaching 0.46 g/MJ with protein level being 10.1% could decrease feed conversion rate of finishing pigs.［Chinese Journal of Animal Nutrition, 2010，22（4）:856-862］