饲粮蛋白质水平降低对成年大鼠生长性能、氮平衡和骨骼肌蛋白质周转的影响  

Effects of Decreasing Dietary Protein Level on Growth Performance,Nitrogen Balance and Skeletal Muscle Protein Turnover of Adult Rats

作　　者：刘璐 楚丽翠 曾祥芳[1] 谯仕彦[1] LIU Lu;CHU Licui;ZENG Xiangfang;QIAO Shiyan(State Key Laboratory of Animal Nutrition,College of Animal Science and Technology,China Agricultural University,Beijing 100193,China)

机构地区：[1]中国农业大学动物科技学院动物营养学国家重点实验室,北京100193

出　　处：《动物营养学报》2019年第5期2222-2231,共10页CHINESE JOURNAL OF ANIMAL NUTRITION

基　　金：现代农业技术体系北京市生猪创新团队

摘　　要：本试验旨在研究饲粮蛋白质水平降低对成年大鼠生长性能、氮平衡和骨骼肌蛋白质周转的影响。试验选取35只初始体重为(238.6±2.3) g的成年SD雄性大鼠,根据体重相近原则分为5组,每组7个重复,每个重复1只大鼠。5组大鼠分别饲喂含有20%(20%C,此为AIN-93G标准饲粮)、15%(15%C)、10%(10%C)、5%(5%C)和0酪蛋白(0C)的5种试验饲粮,并根据AIN-93G推荐量补充各种必需氨基酸。试验期12 d,并在试验第6～11天收集大鼠粪尿以测定氮平衡。在试验第12天早晨对大鼠空腹称重,并一次性腹腔注射L-苯丙氨酸(注射剂量为1.50μmol/g BW,其中含有0.60μmol/g BW的L-[ring-2H5]苯丙氨酸),腹腔注射30 min后眼眶静脉采血,然后将大鼠处死,取后肢的腓肠肌和比目鱼肌。结果显示:1)当酪蛋白含量从20%降至15%并添加各种合成氨基酸后,成年大鼠的平均日增重上升了42.2%(P <0.05),但进一步降低酪蛋白含量并添加各种合成氨基酸后,大鼠的生长受到抑制,体重呈线性下降(P<0.05)。2)大鼠的干物质采食量在酪蛋白含量低于10%时显著下降(P <0. 05),氮摄入量、氮排出量、氮沉积量以及氮沉积率也显著下降(P<0.05)。3)在腓肠肌中,与20%C组相比,10%C组、5%C组和0C组肌肉蛋白质合成速度分别下降了18.25%、33.65%和40.68%(P<0.05),蛋白质降解速度分别提高了17.54%、29.82%和35.09%(P<0.05);在比目鱼肌中,15%C组、10%C组、5%C组和0C组大鼠蛋白质合成速度均比20%C组显著下降(P<0.05),分别下降了9.00%、11.55%、29.15%和33.99%,5%C组和0C组蛋白质降解速度比20%C组显著增加(P<0.05),分别升高了27.66%和57.45%。由此可见,在按标准需要量逐级补充所有必需氨基酸的条件下,当成年大鼠饲粮酪蛋白含量低于10%时,大鼠生长受到抑制,体重下降,氮沉积量减少,骨骼肌蛋白质合成减少、降解增加。因此,在以酪蛋白为唯一氮源的情况下,成年大鼠饲粮中酪蛋白含量降低至15%较适宜。This experiment was conducted to investigate the effects of decreasing dietary protein level on growth performance,nitrogen balance and skeletal muscle protein turnover of adult rats.Thirty-five adult SD male rats with an initial body weight of(238.6±2.3)g were selected and divided into 5 groups according to the principle of similar body weight.Each group consisted of 7 replicates,and each replicate had one rat.Rats in the 5 groups were fed 5 kinds of experimental diets which contained 20%(20%C)(this was AIN-93G standard diet),15%(15%C),10%(10%C),5%(5%C)and 0 casein(0C),respectively,and supplemented with various essential amino acids according to the recommended amount of AIN-93G.The test period was 12 days,and the rats’excrement was collected on the 6th to 11th day to determine the nitrogen balance.On the 12th day morning,the rats were weighed on an empty stomach and intraperitoneally injected with L-phenylalanine(1.50μmol/g BW containing 0.60μmol/g BW of L-[ring-2H 5]phenylalanine).At 30 min after injection,the blood was collected from the orbital vein,and then the rats were sacrificed,the gastrocnemius and soleus muscles of the hind limbs were taken.The results showed as follows:1)when the casein content was reduced from 20%to 15%and synthetic amino acids were added,the average daily gain of adult rats increased by 42.2%(P<0.05),but after further reducing the casein content and adding various synthetic amino acids,the growth of the rats was inhibited and the body weight decreased linearly(P<0.05).2)The dry matter intake of rats decreased significantly when the casein content was less than 10%(P<0.05),and the nitrogen intake,total nitrogen output,nitrogen retention and nitrogen retention rate also decreased significantly(P<0.05).3)In the gastrocnemius muscle,when the casein content of the diet decreased to 10%,5%and 0,the muscle protein synthesis rate decreased by 18.25%,33.65%and 40.68%(P<0.05),and the protein degradation rate increased by 17.54%,29.82%and 35.09%,respectively(P<0.05);in the soleus muscle,

关 键 词：蛋白质水平 成年大鼠 生长性能 氮平衡 蛋白质周转 

分 类 号：S816[农业科学—饲料科学]