3种染料在小鼠胃肠推进试验中的运用

为了筛选胃排空和肠推进试验最佳示踪染料,本试验选取葡聚糖蓝2000、伊文思蓝和墨汁3种染料,用微量倍比稀释法测定一系列浓度各染料在一系列波长的吸光度值,以确定各染料的最大吸收波长和可测浓度范围。根据各染料可测范围确定小鼠最佳灌胃剂量,测定各染料在胃残留率、小肠推进率及小肠均4段各段染料残留率,确定各染料在消化道总残留率。结果显示,在本试验测定波长中,葡聚糖蓝2000、伊文思蓝和墨汁最大吸收波长分别630、630和405 nm;可测浓度范围分别为0.16~5.00 mg/mL（R² =0.9863）、0.78~6.25 μg/mL（R²=0.9984）和0.02%~0.16%（R²=0.9979）。3种染料对胃排空率的影响差异不显著（P > 0.05）,而肠推进率伊文思蓝显著快于其他两种染料（P < 0.05）;3种染料总残留率葡聚糖蓝2000最高,其次为墨汁,伊文思蓝最低,分别为93.6%±4.5%、71.5%±8.5%和18.7%±2.8%。本试验结果提示,在检测受试物对在体消化道运动影响研究中,如果仅要求测定肠推进率可用墨汁,如果要精确检测胃和小肠各段排空情况则用葡聚糖蓝2000为宜。     

基施硒肥对不同生育期紫花苜蓿吸收、转化及利用硒的影响

采用土壤施硒方法,研究基施硒肥对不同生育期紫花苜蓿(Medicago saliva)吸收、转化和利用硒的影响.结果表明:基施硒肥能显著提升紫花苜蓿吸收外源硒的能力(P<0.05);并随生育期延伸呈先升后降的倒"V"型变化,初花期吸收硒能力最强;而紫花苜蓿硒含量随生育期的推移而降低.基施硒肥显著提高紫花苜蓿有机硒的转化率(P<0.05),当施硒量≥0.45 mg·kg^-1时,有机硒转化率 > 50%.紫花苜蓿有机硒转化率随生育期的发展呈下降趋势;紫花苜蓿对硒肥的利用率很低,不超过1.5%;并随生育期的进程先升后降,初花期硒肥利用率最高.施硒量与不同生育期苜蓿硒含量之间存在极显著的线性关系(P<0.01),基施硒肥与苗期牧草硒线性方程为:y=1.9912x+0.1827(R²=0.9696),基施硒肥与分枝期牧草硒线性方程为:y=1.7394x+0.1724(R²=0.9670),基施硒肥与孕蕾期牧草硒线性方程为:y=1.5045x+0.1542(R²=0.9694),基施硒肥与初花期牧草硒线性方程为:y=1.2547x+0.1588(R²=0.9835),基施硒肥与盛花期牧草硒线性方程为:y=1.0044x+0.1500(R²=0.9904).     

APSIM苜蓿模型在宁夏半干旱地区的适应性

基于宁夏3个试验点的数据和同期气象资料,对APSIM模型在宁夏半干旱地区的适应性进行研究。根据试验条件建立相应模型,通过“试错法”对模型相关参数进行校准,实现参数的本地化;并运用多个检验统计指标验证紫花苜蓿（Medicago sativa）土壤含水量及其分别在同心和银川试验点的生育期和干草产量。结果表明：各生育期模拟值和实测值显著相关,决定系数R²分别为0.99和1.00,D值均为0.99,NRMSE分别为2.4%和7.8%;干草产量表现出良好的相关性和一致性,决定系数R²分别为0.82和0.98,D值均为0.99,NRMSE分别为7.1%和9.3%。模拟值比实测值平均高估了7.1%;土壤含水量整体表现出较好的相关性和一致性,决定系数R²为0.82,D为0.85,NRMSE为10%,模拟值比实测值平均高估了10.1%。产量的高估很有可能与水分的高估相关,需要更详细的测量田间试验数据,改善模型土壤参数描述,提高模型预测准确度。校准后的APSIM模型在宁夏半干旱地区具有较好的适应性,可以用于指导该区半干旱区苜蓿生产及栽培措施优化管理。     

Effect of BCB Staining on in vitro Maturation and Development of Nuclear Transfer Embryo of Pig Oocyte

This experiment aimed to study the effect of brilliant cresyl blue (BCB) on in vitro maturation of pig oocytes and the developmental capacity of pig SCNT embryos.The cumulus-oocyte complexes (COCs) were stained with different concentrations of BCB (13,26,39 and 52 μmol/L) for 90 min,and then we divided the COCs into BCB⁺ and BCB^- for in vitro culture 42 to 44 h.The results showed that,with the concentration of BCB increased,the staining rate (20.00%,46.39%,51.66% and 59.03%) raised gradually while the maturation rate of oocytes (74.03%,72.16%,70.53% and 48.61%) reduced,the percentages of oocytes staining by 26 μmol/L BCB for 90 min were higher than that of other groups in staining rate and maturation rate.However,the nuclear maturation rate of BCB⁺ groups were higher than that of BCB^- group.Therefore,26 μmol/L BCB was selected as the most effective concentration dying the oocytes (BCB⁺),which were used as parthenogenetic activation and nuclear transfer embryos.The cleavage and blastocyst rates of parthenogenetic activation and SCNT embryos in BCB⁺ group were significantly higher than that of BCB^- group (P<0.05),but there were no significant differences between the cleavage and blastocyst rates in the groups of BCB⁺ and control (P>0.05).Reconstructed embryos derived from the COCs stained with BCB were transferred to five surrogates,and six cloned piglets were obtained from one of the two pregnant pigs.These results showed that COCs stained with BCB was an effective method to select high-quality oocytes,which could improve the efficiency of in vitro embryo production.     

亮甲酚蓝对猪卵母细胞体外成熟及核移植胚胎发育能力的影响

试验旨在研究亮甲酚蓝(brilliant cresyl blue,BCB)染色对卵母细胞体外成熟及后期胚胎发育潜力的影响。本研究利用13、26、39 、52 μmol/L BCB对成熟培养前的卵丘－卵母细胞复合体(cumulus-oocyte-complexes,COCs)染色90 min,比较各组卵母细胞的着色率、成熟率及孤雌激活胚胎和核移植胚胎的发育情况。结果表明,随着BCB浓度的增加,COCs着色率依次增加(20.00%、46.39%、51.66%和59.03%),但猪卵母细胞体外成熟率逐渐降低(74.03%、72.16%、70.53%和48.61%);不同浓度BCB染色后所得BCB⁺组卵的成熟率均明显高于BCB^-组。试验结果发现,BCB浓度在26 μmol/L时,经染色的COCs既有较高的着色率,且不影响其体外成熟的效率。基于此,研究选取26 μmol/L BCB作为最佳浓度对猪卵母细胞进行染色筛选,然后进行体外培养、孤雌激活及核移植试验。结果显示,筛选的BCB⁺组卵母细胞的孤雌胚和核移植胚的卵裂率和囊胚率均显著高于BCB^-组(P<0.05),而与对照组间无显著差异(P>0.05)。胚胎移植试验挑选BCB⁺组中发育较好的1-2细胞期重组胚对5头代孕母猪进行了移植,其中2头怀孕,1头顺利产下了6头健康胎儿。综合以上试验结果表明,利用BCB染色可作为一种有效的方法筛选体外成熟质量较高的猪卵母细胞,同时提高胚胎体外生产效率。     

农牧交错带半干旱草地生态系统CO2交换对短期不同水平氮添加的响应

本研究以位于山西省右玉县农牧交错带的半干旱草地生态系统为研究对象,探究短期内不同水平的氮添加对半干旱草地生态系统CO_2交换的影响。试验设置8个梯度0、1、2、4、8、16、24和32 g N·m^-2(分别表示为N_0、N_1、N_2、N_4、N_8、N₁₆、N₂₄和N₃₂)。采用静态箱法对草地净生态系统CO_2交换量(NEE)、生态系统呼吸(ER)进行测定,同时监测10 cm表层土壤温度和含水量。试验结果表明:短期氮添加(N₃₂除外)显著增加农牧交错带半干旱草地生态系统净碳交换,NEE、ER和生态系统总初级生产力(GEP)在整个生长季均随氮素添加水平的上升呈单峰型变化趋势,在N₁₆和N₂₄处理下的生态系统CO_2交换达到最高,而N₃₂显著降低了NEE;不同氮添加水平下,ER和GEP相对NEE更为敏感;表层(0～10 cm)土壤温度与含水量影响生态系统CO_2交换,表现为:土壤温度(10 cm)与ER呈显著正相关(R^2>0.1,P<0.05),表层(0～10 cm)土壤含水量与NEE和GEP分别呈显著正相关和显著负相关(R^2>0.1,P<0.05)。因此,短期不同水平氮添加增加了农牧交错带半干旱草地生态系统净碳吸收,对该地区草地生态系统碳的源/汇功能具有一定的参考意义。     

SMALL INTESTINAL EMPTYING TIME IN NORMAL BEAGLE DOGS

Gastric emptying time and small intestinal transit time in dogs are frequently discussed. However, it is often of interest to the radiologist to know what normal small intestinal emptying times should be. A total of 15 upper gastrointestinal studies was performed on five internal parasite-free, normal, standard Beagle dogs with three studies on each dog, 6 days apart. The ages and weights of the dogs ranged from 2–8 years and from 12.4–13.7 kg, respectively. Following 24-hour fasting, a dose of 10 ml/kg bw of 60% wt/vol barium sulfate suspension was administered through a stomach tube. Then, sequential radiographs were made at 30-minute intervals until the entire contrast medium column was in the colon and cecum. The mean, standard deviation, and range of gastric emptying time, small intestinal transit time, and small intestinal emptying time were 76 ± 16.7 (30–120), 73 ± 16.4 (30–120), and 214 ± 25.1 (180–300) minutes, respectively. This study offers the possibility that small intestinal emptying time may be used to further evaluate patients with suspected small intestinal partial obstruction, pseudo-obstruction, ischemia, or lymphangiectasia.     

亮甲酚蓝染色对牛卵母细胞体外成熟和凋亡的影响

为了探讨亮甲酚蓝(brilliant cresyl blue,BCB)对牛未成熟卵母细胞染色选择后对其体外成熟(IVM)和凋亡的影响,本研究在牛卵母细胞成熟培养前用26 μmol/L BCB染色90 min作为处理组,以未染色卵母细胞作为对照组;将处理组依照胞质的颜色分为蓝色组(BCB⁺)和无色组(BCB^-),成熟培养后检测卵子的发育能力。结果表明:①经BCB染色卵母细胞在成熟后,BCB⁺组卵母细胞成熟率(80.92%)较对照组(60.00%)和BCB^-组(51.61%)差异显著(P<0.05);②BCB⁺组的凋亡率(6.50%)较对照组(28.21%)、BCB^-组(39.06%)差异显著(P <0.05),随着卵母细胞发育潜能的升高其凋亡率逐渐降低。由此可见,以亮甲酚蓝染色为基础的牛卵丘-卵母细胞复合体的区分可以用来有效的选择更具发育活力的牛卵母细胞。     

GASTRIC EMPTYING OF SOLID RADIOPAQUE MARKERS IN HEALTHY DOGS

The gastric emptying of 1.5 mm diameter (small) and 5.0 mm diameter (large) radiopaque markers (BIPS) was assessed in 20 dogs. The markers were fed to the dogs in a test meal and abdominal radiographs were made hourly thereafter. Studies were repeated three times in each dog. The variation between two veterinarians interpreting the radiographs was low. The sex, age and day of the study did not have a significant effect on the lag phase or the time taken to empty 25%, 50% and 75% of the markers (T₂₅, T₅₀ and T₇₅ respectively). There was a weak but significant positive correlation between the body weight and T₅₀. There was no significant difference in gastric emptying parameters between the large and small markers.
The mean gastric emptying versus time curve of the small markers on day one was chosen to represent the reference curve for healthy dogs. The lag phase of the small markers on day one was 2.45 ± 2.04 hours, the T₂₅ was 4.85 ± 2.15 hours, the T₅₀ was 6.05 ± 2.99 hours and the T₇₅ was 8.32 ± 2.72 hours (mean ± SD).     

单宁酸对生长猪胃-小肠仿生消化中消化酶活性及饲粮粗蛋白消化率的影响

本试验旨在探讨单宁酸对生长猪胃、小肠仿生消化中消化酶活性及玉米-豆粕型饲粮干物质和粗蛋白消化率的影响，为评价单宁酸的生物学效应提供参考。试验一采用单因素完全随机设计，考察在无饲粮下2种单宁酸对猪模拟胃液、模拟小肠液消化酶活性的影响。设5个处理，单宁酸添加量分别为0 mg （胃液体积为20 mL，小肠液体积为22 mL）；单宁酸1，10 mg；单宁酸1，20 mg；单宁酸2，10 mg；单宁酸2，20 mg。测定各处理的胃蛋白酶、淀粉酶、胰蛋白酶和糜蛋白酶的活性。试验二考察玉米-豆粕型饲粮添加单宁酸对猪仿生消化中胃、小肠阶段消化酶活性及养分消化率的影响。采用单因素完全随机设计，设5个处理，单宁酸在饲粮中的含量分别为0 mg·（2 g）^-1；单宁酸1，10 mg·（2 g）^-1；单宁酸1，20 mg·（2 g）^-1；单宁酸2，10 mg·（2 g）^-1；单宁酸2，20 mg·（2 g）^-1。测定仿生消化中胃阶段0.5和4 h时胃蛋白酶活性，小肠阶段0.5、4和8 h时淀粉酶、胰蛋白酶和糜蛋白酶活性及生长猪胃-小肠仿生消化测定饲粮的干物质和粗蛋白消化率。结果表明：1）无饲粮的情况下，和空白对照组相比，2种单宁酸对模拟胃液中胃蛋白酶活性无显著影响（P>0.05），单宁酸1比单宁酸2更高地降低了模拟小肠液中淀粉酶、胰蛋白酶和糜蛋白酶的活性（P<0.05）。2）在饲粮进行仿生消化的胃消化0.5～4 h内，除4 h时10 mg·（2 g）^-1添加量外，添加单宁酸1时胃蛋白酶的活性均显著高于添加单宁酸2时的相应值（P<0.05），除单宁酸2在消化0.5 h外，2种单宁酸在添加10 mg·（2 g）^-1时胃蛋白酶活性均显著高于20 mg·（2 g）^-1添加量的相应值（P<0.05）。在小肠仿生消化0.5 h时，饲粮中添加单宁酸1、2的2个水平对消化液中淀粉酶活性无显著影响（P>0.05），但均显著降低了糜蛋白酶的活性（P<0.05）；单宁酸1的消化液中胰蛋白酶活性高于单宁酸2的相应值（P<0.05）。在小肠仿生消化4 h时，除添加水平为20 mg·（2 g）^-1时的糜蛋白酶活性外，饲粮中添加单宁酸1消化液中淀粉酶、糜蛋白酶活性高于添加单宁酸2的相应值，而胰蛋白酶活性低于添加单宁酸2的相应值（P<0.05）。单宁酸1、2的两个添加量均降低了胰蛋白酶和糜蛋白酶的活性（P<0.05）。在小肠仿生消化8 h时，饲粮中单宁酸的添加量影响了淀粉酶的活性，但单宁酸1和单宁酸2各两个添加量在淀粉酶的平均活性上无显著差异（P>0.05）。单宁酸1、2的两个添加量均降低了胰蛋白酶、糜蛋白酶的活性（P<0.05）。3）与对照组相比，两种单宁酸在两种添加水平下均显著降低了饲料粗蛋白消化率（P<0.05），且单宁酸2比单宁酸1更多地降低了饲粮粗蛋白的消化率（P<0.05）。综上所述，在有、无饲粮条件下，单宁酸对消化酶活性呈现不一致影响。单宁酸影响饲粮粗蛋白的消化率可能主要与消化液中糜蛋白酶活性降低以及单宁酸与饲粮中的化学成分形成螯合物降低了小肠消化酶的水解效率有关。     

EVALUATION OF SOLID PHASE RADIOLABELS OF DOG FOOD FOR GASTRIC EMPTYING

99mTc-Pertechnetate, 99mTc-mebrofenin, 99mTc-disofenin, 99mTc-sulfur colloid, and 99mTc-Dowex resin beads were evaluated for in vitro stability as a label for both dry extruded, and canned dog food for gastric emptying scintigraphy. A sample of each radiolabeled diet was added to water, gastric juice, intestinal juice, or gastric juice followed by intestinal juice for in vitro digestion. After a 3-hour digestion period, tubes were centrifuged and percentage solid phase retention (%SPR) was calculated. The experiment was repeated three times over a 14-day period to minimize day-to-day variation. For dry dog food, 99mTc-mebrofenin and 99mTc-disofenin had similar %SPR in water (96 and 93%, respectively) and gastric juice (>95% each) and were significantly higher than other labels. For canned dog food, mebrofenin had a 91% SPR for the water or gastric juice digestions, and 99mTc-Dowex had a %SPR of >99%. 99mTc-mebrofenin and 99mTc-Dowex were also tested in vivo, where 99mTc-Dowex had poor stability, and 99mTc-Mebrofenin had excellent stability. 99mTc-Mebrofenin is a suitable label for dog food for gastric emptying scintigraphy.     

利用体外模拟瘤胃发酵技术预测奶牛生产性能的研究

本试验旨在利用全混合日粮（TMR）体外发酵参数预测奶牛的生产性能,采集2头体重550 kg、安装永久瘤胃瘘管的健康荷斯坦奶牛瘤胃液,并取40种不同的TMR进行体外发酵试验,测定体外发酵24 h的乙酸、丙酸、丁酸、氨态氮（NH₃-N）含量,以及甲烷（CH₄）排放量、微生物蛋白质（MCP）、体外干物质消失率（IVDMD）、体外蛋白质消失率（IVCPD）和体外有机物消失率（IVOMD）等指标。记录饲喂不同TMR的奶牛对应的生产性能（产奶量、乳蛋白率、乳脂率）,并与奶牛生产性能之间建立预测模型。结果显示：①产奶量与丙酸含量（r=0.37,P<0.05）、MCP（r=0.40,P<0.05）均呈显著正相关,但与IVCPD（r=-0.44,P<0.01）呈极显著负相关;乳脂率与乙酸含量（r=0.55,P<0.01）、甲烷排放量（r=0.36,P<0.05）、MCP（r=0.40,P<0.05）呈极显著或显著正相关;乳蛋白率与MCP（r=0.91,P<0.01）、IVDMD（r=0.44,P<0.01）、IVCPD（r=0.45,P<0.01）呈极显著正相关,但是与IVOMD（r=-0.56,P<0.01）呈极显著负相关。②奶牛的生产性能可用体外发酵参数作为预测因子进行预测。产奶量（kg/d）=29.72-0.86IVCPD（R²=0.73,RSD²=47.26,P<0.001）;乳脂率（%）=0.40+0.06AA（R²=0.91,RSD²=0.15,P<0.001）;乳蛋白率（%）=1.52+0.06MCP（R²=0.78,RSD²=0.01,P<0.001）。奶牛的生产性能预测值与实际值的误差在允许的范围内,表明预测方程是可行的。     

伊维菌素微乳中伊维菌素的含量测定方法研究

为建立伊维菌素微乳中伊维菌素含量的高效液相色谱（HPLC）测定方法,选用Hypersil ODS2 （5 μm,4.6 mm×250 mm）色谱柱,流动相为甲醇∶乙腈∶水为35∶60∶5（V/V/V）,检测波长为244 nm,柱温为30 ℃,流速为1 mL/min进行测定。结果显示,伊维菌素在该色谱条件下,系统适应性良好,在80~320 μg/mL浓度范围内线性关系良好,回归方程为：Y=22 700X+2 510,R²=0.9998,总平均回收率为101.90%±2.94%,RSD为2.88%,对中试生产的3批伊维菌素微乳进行含量测定,RSD为1.86%。表明该含量测定方法准确可靠,重现性好,可用于伊维菌素微乳中伊维菌素含量的测定,并为该新型制剂的质量标准的制定和质量评价提供依据,也为后期的临床安全应用提供可靠的参考。     

2018年中国部分地区猪瘟病毒2.1d亚型新流行株的基因组特征分析

为了解中国猪瘟病毒（classical swine fever virus，CSFV）的分子流行病学及遗传变异情况，本研究应用RT-PCR方法对2018年采集自河南、河北、山东、黑龙江和辽宁5个省份的350份疑似CSFV感染的病料进行E2和NS5B基因扩增，并对PCR产物进行测序和序列分析。结果显示，350份样品中21份为CSFV阳性，共获得14株CSFV的E2基因序列和7株CSFV的部分NS5B基因序列。E2全基因、NS5B部分基因序列分析表明，21份阳性样品均属于近年来在中国流行的CSFV 2.1d亚型，且新发现的2.1d亚型CSFV与中国较早2.1d亚型CSFV毒株间同源性差异不大，新发现的2.1d亚型CSFV分离株在E2基因的6个氨基酸（R³¹、S³⁴、W¹⁸²、K²⁰⁵、K³⁰³、A³³¹）上具有相同的分子特征，E2蛋白中15个位点上的半胱氨酸均未发生变异。韩国2.1d亚型CSFV在E2蛋白上具有3个独特的氨基酸（N⁹⁷、K¹⁵⁹、R²⁰⁵）特征，并且发现了韩国毒株YC11WB可能作为2.1b和2.1d亚型CSFV过渡毒株的证据，流行于中国和韩国的2.1d亚型CSFV可能分别来自于本国早期2.1b亚型CSFV的衍化。本研究证实，2018年中国及周边国家CSFV较为活跃，且流行毒株依然以2.1d亚型为主，为中国科学防控CSFV提供了依据。     

Content Determination of Ivermectin in the Ivermectin Microemulsion Injection

In order to establish the determination method of ivermectin (IVM) in the ivermectin microemulsion injection by high performance liquid chromatography (HPLC), Hypersil ODS2 colunm (5 μm,4.6 mm×250 mm) was used in this study. The mobile phase composed of methanol, acetonitrile and water (35:60:5,V/V/V) at a flow rate of 1 mL/min. The detection wave length was set at 244 nm and the column temperature was 30 ℃. The results showed that the HPLC system suitability of IVM was good. A good linear correlation of IVM was observed within the concentration range 80 to 320 μg/mL, and the average recovery rate was 101.90%±2.94% with RSD was 2.88%, the regression equation was Y=22 700X+2 510 (R²=0.9998). The RSD of IVM content in ivermectin microemulsion injection was 1.86%. The method was accurate and reliable,reproducible,easy to operate, which could be used in new type of ivermectin microemulsion injection. The method could be used as the basis of quality control and establishing a quality standard, and to provide basis for quality evaluation, also can provide reliable reference for safe veterinary clinical application in the future.     

蓝狐消化道5-羟色胺和生长抑素免疫组化定位

采用免疫组织化学SP法.研究蓝狐消化道内5-羟色胺和生长抑素2种免疫阳性细胞的形态结构与分布密度.结果表明,消化道中这2种免疫阳性细胞形态多呈圆形、椭圆形或锥体形,主要集中分布在胃腺上皮、肠上皮及肠腺上皮细胞之间.5-HT免疫阳性细胞数量以结肠最多,直肠和空肠次之,胃底腺区、十二指肠、回肠和幽门腺区较少,食管、贲门腺区和盲肠中未见:SS免疫阳性细胞大量出现于幽门腺区,食管、责门腺区和盲肠中未见;根据其形态推测,蓝狐消化道这2种免疫阳性细胞有内、外2种分泌功能.     

基于植被指数的典型草原光合有效吸收比例估算研究

采用常用的8种植被指数,对植被光合有效吸收比例（FPAR）数据进行了反演。结果表明,叶面积指数较大时,绿度植被指数（GNDVI）、转换型土壤调整植被指数（TSAVI）估算FPAR的效果较好,R²分别达到0.908和0.895;而当叶面积指数较小时（<0.5）,TSAVI和土壤调整植被指数（SAVI）估算FPAR可有效克服土壤等背景因素的影响,R²分别达到0.819和0.807。有效的组合近红外、红光波段的反射率构建植被指数可以提高FPAR的估算精度。     

The sites in the duodenum of receptor areas which affect abomasal emptying in the calf

Calves were prepared with abomasal and duodenal cannulae to assess the effects on abomasal emptying of duodenal infusates at different rates and different sites. In two calves infusions of isotonic NaHCO3 or 60 mM HCl 30 cm distal to the pylorus were as effective in controlling abomasal emptying as infusions of the duodenum from 5 cm distal to the pylorus, and in three other calves they were as effective as perfusing the whole duodenum including the most proximal 5 cm. Reducing the rate of duodenal infusion of 60 mM HCl from 10 to 2.5 ml/min diminished its effect from total inhibition of gastric emptying to slight or negligible inhibition. The stimulation of gastric emptying by duodenal infusion of isotonic NaHCO3 solution was undiminished by reduced rates of infusion. It is proposed that in the calf receptors which activate and inhibit gastric emptying are present throughout the duodenum.     

叶绿素含量对C3、C4植物叶绿素荧光参数的影响

以草原常见牧草C₄植物木地肤和C₃植物苜蓿为材料,在野外使用OS5P+叶绿素荧光仪,分析光合有效辐射(PAR)与叶绿素荧光(ChF)参数之间的关系;使用CCM-300手持式叶绿素仪,测量叶片叶绿素含量(Chl),分析叶绿素含量对PAR与ChF的影响。结果表明,两种植物PAR与光合系统Ⅱ光量子产额[Y(Ⅱ)]、电子传递速率(ETR)之间都呈现出相似的对数趋势,木地肤的PAR与Y(Ⅱ)对数拟合度R 2=0.71,苜蓿的PAR与Y(Ⅱ)对数拟合度R²=0.81,都表现出PAR值在500μmolm^-2s^-1附近Y(Ⅱ)达到较高水平;在充分考虑叶绿素含量的情况下,原本聚集在PAR值500μmolm^-2s^-1附近的点分散在了趋势线的两侧,使数据分布更加均匀。     

Action of long(R)-insulin-like growth factor-1 on protein metabolism in beef heifers

Insulin-like growth factor-1 (IGF-1) is perhaps the most important endogenous factor controlling growth. Most studies to date in livestock have shown that IGF-1 has greatest efficacy when animals are in a catabolic state. We have determined the effects of an iv infusion of the IGF-1 analog Long(R³)-IGF-1 on protein metabolism in beef heifers that were slowly losing liveweight because of restricted feeding. There was a tendency for both whole-body protein and skeletal muscle protein to be conserved in Long(R³)-IGF-1-treated heifers. Long(R³)-IGF-1 administration markedly reduced the plasma concentrations of all amino acids measured and glucose. There was a significant change in the profile differences of endogenous plasma IGF-1 concentrations during the 8-hr infusion period, with plasma IGF-1 decreasing sharply in the test group. There was a significant difference in mean profiles for plasma IGF-2 between the test and control groups. Overall, plasma IGF-2 for the control group decreased only slightly over time (about 40 ng/ml), whereas the test group decreased dramatically (by about 140 ng/ml). Increased plasma concentrations of a 31–32-kDa IGF-binding protein (possibly IGF-binding protein-1) in the treated group was detected by radioligand blot. We found that Long(R³)-IGF-1 infusion tended to preserve whole-body and muscle protein in beef heifers on a low-quality diet, and suggest that further investigation of this treatment may provide an alternative approach to reducing weight loss during the dry season.