中文摘要：

本试验旨在研究不同蛋白质水平日粮对肥育猪肠道氨基酸转运载体CAT1 mRNA表达量的影响。选取36头杜×长×大三元杂交阉公猪，平均体重（55．6±7．0）kg，随机分为3个处理，分别饲喂13％（低蛋白质组）、16％（对照组）和19％（高蛋白质组）的蛋白质水平日粮，每个处理12个重复（单栏饲养）。于饲喂后第45天，每组随机屠宰5头，分离肠道（十二指肠、空肠和回肠），运用Real-Time PCR技术，以β-actin为内参基因，研究CAT1 mRNA相对于p．actin的表达量。结果表明，在饲喂高蛋白质日粮时，与对照组相比，氨基酸转运载体CAT1 mRNA相对于内参β—actin mRNA的表达量，在肥育猪十二指肠、空肠和回肠中分别提高了58．4％、23．2％和24．5％，但差异不显著（P〉0．05）；而饲喂低蛋白质日粮时，CAT1 mRNA相对表达量在肥育猪十二指肠和空肠中则分别提高93．1％和122．6％，差异显著（P〈O．05），而在回肠中降低了14．3％，差异不显著（P〉0．05）。高蛋白质水平日粮对肥育猪肠道CAT1 mRNA相对表达量的影响不大，而低蛋白质水平日粮对肥育猪肠道CAT1 mRNA相对表达量的影响较大，尤其是对空肠CAT1 mRNA的相对表达量。

英文摘要：

The objective of this experiment was to study the effects of the diets of different protein levels on the expression of cationic amino acid transporter （CAT 1） mRNA in the small intestine of the finishing pigs. Thirty-six castrated male Duroc ; Landrace x Large White pigs, with an average initial live weight of （55.6 ± 7.0） kg, were randomly allocated to three dietary treatments with 3 replicates in each treatment. The pigs were housed individually in floor pens and fed with diets of protein levels of 13% （low protein group）, 16% （control group） and 19% （high protein group） respectively. After 45 days, five pigs were slaughtered randomly in each treatment. Small intestinal segment samples were collected from duodenum, jejunum and ileum for detection the relative expression of CAT1 mRNA by Real-Time PCR,with β-actin as reference gene. In comparison with control group （CP 16%）, the relative expression of CAT1 mRNA with β-actin as reference gene was increased by 58.4%, 23.2% and 24.5% respectively of the duodenum, jejunum and ileum of the finishing pigs, but the difference was not significant （P〈0.05）. The relative expression of CAT1 mRNA increased by 93.1% and 122.6% respectively of duodenum and jejunum of the finishing pigs fed with low-protein level （13%） diet and the difference were significant （P〈0. 05）. But for the relative expression of CAT1 mRNA of ileum of the finishing pigs fed with low-protein level （13%） diet, the value was reduced by 14. 3% with no significant difference（P〉0.05）. Therefore, the effects of high.protein （19%） diet on the CAT1 mRNA expression in the small intestine of the finishing pigs was not very significant, but the low-protein （13%） diet had significant effects on the CAT1 mRNA expression of the small intestine of the finishing pigs, especially for the relative expression of CAT1 mRNA of the jejunum.