Ractopamine对肥育期大约克猪胴体组成及肉质的影响

用含20mg/kg Ractopamine的饲粮饲喂纯种肥育期大约克猪(始重60 kg,终重90 kg),进行屠宰试验。胴体测定表明:添加Ractopamine明显改变了胴体组成,胴体瘦肉率提高3.53％(P<0.05)。其中半腱肌、背最长肌、半膜肌、股二头肌和腹侧锯肌重量分别增加10.7％(P<0.01)、9.1％(P<0.01)、7.4％(P<0.05)、7％(P<0.05)和4.5％(P<0.05);背最长肌面积增大6.5％(P<0.05);胴体脂肪率降低了3.21％(P<0.05),背膘厚度呈降低趋势,其中髻甲部降低9％(P<0.05)。肉质测定显示,眼肌肉色、大理石纹及失水率等内质指标对照组与试验组均无明显差异,但背最长肌粗蛋白含量提高2.8％(P<0.05),粗脂肪降低3.67％(P<0.01)。

Ractopamine对不同性别大约克猪的效果

以大约克猪为试验对象，研究Ｒａｃｔｏｐａｍｉｎｅ对不同性别肥育猪生产性能、胴体组成以及血清性激素水平的影响．结果表明：饲粮中添加Ｒａｃｔｏｐａｍｉｎｅ２０ｍｇ／ｋｇ，阉公猪日增重提高１１．５％（Ｐ＜０．０１），但对其它性别的肥育猪则无明显的影响；Ｒａｃｔｏｐａｍｉｎｅ明显改善了阉公猪、阉母猪和小母猪的胴体组成．其中以对小母猪的效果最佳，可提高胴体瘦肉率９．６％（Ｐ＜０．０１），降低脂肪率１６．２６％（Ｐ＜０．０１）．此外，血清性激素测定表明，Ｒａｃｔｏｐａｍｉｎｅ使公猪睾酮浓度升高３０％（Ｐ＜０．０５），母猪孕酮浓度升高７８％（Ｐ＜０．０１），雌二醇升高１４％（Ｐ＜０．０５）；统计分析显示，性激素和Ｒａｃｔｏｐａｍｉｎｅ均能影响大约克猪的生长性能和胴体组成。

Separation and enrichment of trace ractopamine in biological samples by uniformly-sized molecularly imprinted polymers

In order to prepare a high capacity packing material for solid-phase extraction with specific recognition ability of trace ractopamine in biological samples, uniformly-sized, molecularly imprinted polymers （MIPs） were prepared by a multi-step swelling and polymerization method using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and toluene as a porogen respectively. Scanning electron microscope and specific surface area were employed to identify the characteristics of MIPs. Ultraviolet spectroscopy, Fourier transform infrared spectroscopy, Scatchard analysis and kinetic study were performed to interpret the specific recognition ability and the binding process of MIPs. The results showed that, compared with other reports, MIPs synthetized in this study showed high adsorption capacity besides specific recognition ability. The adsorption capacity of MIPs was 0.063 mmol/g at 1 mmol/L ractopamine concentra- tion with the distribution coefficient 1.70. The resulting MIPs could be used as solid-phase extraction materials for separation and enrichment of trace ractopamine in biological samples.

Lateral Flow Immunoassay for Quantitative Detection of Ractopamine in Swine Urine

A strip reader based lateral flow immunoassay （LFIA） was established for the rapid and quantitative detection of ractopamine （RAC） in swine urine. The ratio of the optical densities （ODs） of the test line （AT） to that of the control line （Ac） was used to effectively minimize interference among strips and sample variations. The linear range for the quantitative detection of RAC was 0.2 ng/mL to 3.5 ng/mL with a median inhibitory concentration （IC50） of 0.59＋0.06 ng/mL. The limit of detection （LOD） of the LFIA was 0.13 ng/mL. The intra-assay recovery rates were 92.97%, 97.25%, and 107.41%, whereas the inter-assay rates were 80.07%, 108.17%, and 93.7%, respectively.

不同饲粮蛋白水平下Ractopamine对肥育猪生长性能和胴体组成的影响

选用４０头杜长大肥育猪进行饲养和屠宰试验，研究了Ｒａｃｔｏｐａｍｉｎｅ对饲喂不同蛋白（１３．５０％和１８．００％）水平饲粮肥育猪生长性能和胴体组成的影响。试验结果表明：在１８．００％蛋白水平下，Ｒａｃｔｏｐａｍｉｎｅ（２０ｍｇ／ｋｇ）使猪日增重提高了９．０３％（Ｐ＜０．０５），料重比下降了１４．４８％，而在１３．５０％蛋白水平下，Ｒａｃｔｏｐａｍｉｎｅ对日增重和料重比均无明显影响；添加Ｒａｃｔｏｐａｍｉｎｅ，胴体组成发生了明显改变，饲粮蛋白为１３．５０％和１８．００％时，胴体瘦肉率分别提高了４．５（Ｐ＜０．０５）和４．１８个百分点（Ｐ＜０．０１），脂肪率分别下降了４．０９（Ｐ＜０．０５）和４．１９个百分点（Ｐ＜０．０１）；此外，本研究发现Ｒａｃｔｏｐａｍｉｎｅ对不同骨骼肌的作用效果存在显著差异，背最长肌、股二头肌和半腱肌明显增大（Ｐ＜０．０５），而股四头肌和臀中肌无明显变化。肉质测定显示，Ｒａｃｔｏｐａｍｉｎｅ对背最长肌大理石纹、色泽、系水力、ｐＨ值等指标均无显著影响。

Zinc Alters Ractopamine HCl Response in Cultured Skeletal Muscle Cells

The objective of this study was to determine if zinc, when added in combination with ractopamine hydrochloride (RH), would stabilize the interaction of RH with the β-adrenergic receptor, as indicated by altered cAMP concentrations, mRNA quantity, or protein abundance. Cultured bovine skeletal muscle cells were established and treated after 120 h for 6, 24, and 96 h with differentiation media of specific treatments. Treatments were applied in a factorial arrangement with two levels of zinc (0 μM or 1 μM) and two levels of RH (0 μM or 10 μM) in differentiation media. cAMP levels were measured at 6, 24, and 96 h, while mRNA and protein were measured at 24 and 96 h. At 6 h, no differences (P > 0.05) were detected in cAMP levels between the treatments. However, at 24 h the 10 μM RH, 1 μM zinc treatment had the greatest concentrations of cAMP (P < 0.05). At 96 h the 10 μM RH, 0 μM zinc treatment had a lower concentration of cAMP (P = 0.05) compared to the control. No differences were detected in mRNA (β1-adrenergic receptor, β2-adenergic receptor, AMPKα, myosin heavy chain I, myosin heavy chain IIA, and myosin heavy chain IIX) concentrations between treatments. Protein quantity of the β1-adrenergic receptor and β2-adrenergic receptor did not differ between treatments. These results indicate that zinc, in combination with RH, may help sustain the RH response during prolonged exposure as indicated by increased cAMP concentrations.

Ractopamine Hydrochloride and Estradiol + Trenbolone Acetate Implants Alter Myogenic mRNA, <i>β</i>-Adrenergic Receptors, and Blood Metabolites

Two commonly used growth promotants in the United States beef industry are β-agonists and anabolic steroid hormones. Each has been shown to increase lean muscle deposition in cattle provided treatments of each growth technology, but much is still unknown of how steroidal implants and β-agonists work in combination. It was our goal to determine the effect of implant strategy and β-agonist administration in beef feedlot heifers (n = 264). A 3 × 2 factorial randomized complete block design was used with 2 levels of OPT and 3 different durations of terminal implant (TI) windows for a total of 6 treatment groups with 9 replications. Terminal implants (20 mg estradiol/200 mg trenbolone acetate implant, Component TE-200) were provided to heifers 140 d from slaughter (TI140), 100 d from slaughter (TI100), or 60 d from slaughter (TI60). Animals receiving the later two TI being first implanted on day 0 (8 mg estradiol/80 mg trenbolone acetate implant, Component TE-IH). The second treatment of the cattle received was the orally active beta adrenergic agonist, ractopamine-hydrochloride (RH) in the form of Optaflexx®(OPT;0 (NO) or 200 (YES) mg/hd·d-1) over the final 28 days of the trial. Thirty animals were subjected to longissimus muscle (LM) biopsies on d 0, 40, 80, 112, and at slaughter on d 140 to view mRNA levels of myogenic related genes and protein quantities of the β1-adrenergic receptor (β1 AR) and β2-adrenergic receptor (β2 AR). On the same days, blood samples were taken from 108 animals to assess changes in plasma blood urea nitrogen (BUN), non-esterified fatty acids (NEFA) and progesterone due to treatments. Relative mRNA levels of myosin heavy chain IIX (MHC IIX), AMPKα, and IGF-I were increased (P < 0.05) in animals receiving a TI100 over the other two implant dates after OPT was fed to animals. After OPT administration myosin heavy chain IIA (MHC IIA) mRNA levels tended to decrease (P = 0.09) due to OPT. An interaction between TI d and OPT administration caused an increase (P < 0.05) in MHC IIA mRNA level in the TI60/Yes treatment group over all other treatments except the TI100/No treatment group. Protein intensity of the β2 AR was decreased (P < 0.05) by the latest TI d (TI60) during OPT feeding, while β1 AR protein intensity tended to be lower (P < 0.10) in animals fed OPT. Plasma BUN levels were reduced (P < 0.05) after terminal implants and OPT feeding;while progesterone was decreased (P < 0.05) by OPT alone. Neither growth promotant affected NEFA levels in plasma. Collectively, these data indicate that ractopamine hydrochloride and estradiol + trenbolone acetate implants alter myogenic mRNA, β-adrenergic receptors, and blood metabolites in finishing beef heifers.

An immunoassay based on lab-on-a-chip for simultaneous and sensitive detection of clenbuterol and ractopamine

Both clenbuterol(CLB)and ractopamine(RAC)areβ-adrenergic agonists.After long-term excessive intake,there will be adverse reactions such as headache,chest tightness,limb numbness,and serious lifethreatening.Simultaneous detection of CLB and RAC in related samples is of great importance for human health.In this work,we outline a microfluidics-based indirect competitive immunoassay(MICI)system that can sensitively detect residual CLB and RAC in pork,swine blood and swine urine.The rapid detection of multiple samples can be achieved in one chip,which greatly improves the detection efficiency.This method has good stability and reproducibility and the microfluidic chips are easy to manufacture.The linear ranges for CLB and RAC detection by MICI are 0.1-2.5 ng/mL and 0.1-5 ng/mL,and the limits of detection(LODs)are 0.094 ng/mL and 0.091 ng/mL,respectively.This straightforward and portable immunoassay system provides a good platform for rapid detection of harmful substances in food samples.

Fate and transport of theβ-adrenergic agonist ractopamine hydrochloride in soil–water systems

The feed additive ractopamine hydrochloride was fortified at four concentrations into batch vials containing soils that differed in both biological activity and organic matter（OM）.Sampling of the liquid layer for 14 days demonstrated that ractopamine rapidly dissipated from the liquid layer. Less than 20% of the fortified dose remained in the liquid layer after 4 hr,and recoveries of dosed ractopamine ranged from 8 to 18% in the liquid layer at 336 hr. Sorption to soil was the major fate for ractopamine in soil：water systems, i.e., 42%–51% of the dose at14 days. The major portion of the sorbed fraction was comprised of non-extractables; a smaller fraction of the sorbed dose was extracted into water and acetone, portions which would be potentially mobile in the environment. Partitioning coefficients for all soils suggested strong sorption of ractopamine to soil which is governed by hydrophobic interactions and cation exchange complexes within the soil OM. Ractopamine degradation was observed, but to mostly non-polar compounds which had a higher potential than ractopamine to sorb to soil. The formation of volatiles was also suggested. Therefore, despite rapid and extensive soil sorption,these studies indicated a portion of ractopamine, present in manures used to fertilize soils,may be mobile in the environment via water-borne events.

Ractopamine up take by alfalfa (Medicago sativa) and wheat (Triticum aestivum) from soil

Ractopamine is a beta adrenergic agonist used as a growth promoter in swine, cattle and turkeys. To test whether ractopamine has the potential to accumulate in plants grown in contaminated soil, a greenhouse study was conducted with alfalfa（Medicago sativa） and wheat（Triticum aestivum） grown in two soils having different concentrations of organic matter（1.3% and 2.1%）, amended with 0, 0.5, and 10 μg/g of ractopamine. Plant growth ranged from 2.7 to 8.8 g dry weight（dw） for alfalfa, and 8.7 to 40 g dw for wheat and was generally greater in the higher organic matter content soil. The uptake of ractopamine in plant tissues ranged from non-detectable to 897 ng/g and was strongly dependent on soil ractopamine concentration across soil and plant tissue. When adjusted to the total fortified quantities, the amount of ractopamine taken up by the plant tissue was low, 〈 0.01% for either soil.

莱克多巴胺快速检测竞争ELISA试剂盒的研制及其性能测定(英文)

Mixed anhydride(MA)was used to conjugate ractopamine(RAC)to BSA and obtained artificial antigen BSA-RAC identified by UV and SDS-PAGE.Balb/c mice were immunized with BSA-RAC and hybridoma lines that secrete RAC monoclonal antibody(mAb)were generated with cell fusion.A ciELISA kit for detection of RAC(RAC-Kit)was developed with RAC mAb and its performance were tested.The results indicated that BSA-RAC was successfully synthesized and its conjugation ratio of RAC to BSA was about 24.5∶1.Three hybridoma lines were filtered and the best one was 4D8-3E11,its affinity constant(Ka)was 1.65×1010 L/mol.The limit of detection of RAC-Kit was 0.5 ng/ml and its detection range was 0.5-184 ng/ml.The mean recoveries of RAC spiked in feed were 85.6% and in swine urine were 88.6%.The precision and accuracy of the assay as determined by inter-assay and intra-assay coefficient variation were below 15%.It had 9.4% cross-reactivity(CR%)to dobutamine and little or no CR to other compounds.The validity of RAC-Kit in 4 ℃ was in 180 d.

Segmental arterial mediolysis: A clinical-pathologic review, its role in fibromuscular dysplasia and description and differential diagnosis of the masquerader-muscular artery cystic necrosis

Segmental arterial mediolysis (SAM) is an uncommon non-inflammatory iatrogenic arteriopathy caused by alpha-1 adrenergic agonists or Beta-2 agonists able to release norepinephrine from the peripheral nervous system. Causative agents include adrenergic agonists used to control blood pressure, B-2 tocolytic agonists, and ractopamine used as a repartitioning agent in animal husbandry. The liberated norepinephrine both injures and stimulates a robust reparative response in the muscular arteries in the abdomen, brain base, and coronary arteries. This response may be augmented by endothelin-1 formed in the arterial adventitia. Three types of arterial lesions develop in the injurious stage: 1) apoptotic induced mediolysis, 2) separation of the outer media from the adventitia and 3) the formation of arterial gaps. The latter enlarge, particularly in elderly patients, to form gap-aneurysms complicated by dissections and dissecting an- eurysms that when ruptured cause the calamitous hemorrhages that clinically announce SAM. The other types of injury remain clinically silent but with repair develop sequelae and can metamorphose into fibromuscular dysplasia. The sequelae are mainly asymptomatic but may cause arterial stenosis and ischemic lesions. The definitive diagnosis of SAM re- quires histological conformation but misinterpreta- tion of smooth muscle vacuolar change has caused di- agnostic errors. Muscular artery cystic necrosis a newly named non-inflammatory muscular artery ar- teriopathy may be confused with SAM both clinically and pathologically. This arteriopathy represents the muscular artery equivalent of cystic media necrosis of the elastic arteries since it exhibits similar morphol- ogic features and can occur concomitantly with this entity. Adrenergic agents to counter hemorrhagic shock in SAM are contraindicated since they may intensify injury and create new lesions. The use of norepinehrine antagonists introduces a new, but as yet untested, treatment option for SAM.

Development of a reversed dispersive based graphene functionalized with multiwalled carbon nanotubes for detection ofβ2-agonists in pork by high-performance liquid chromatography

A reliable and inexpensive pretreatment procedure in the determination ofβ2-agonists in pork was developped.The procedure used a nanocomposite of multiwalled carbon nanotubes(CNTs)functionalized with graphene(rGO)as the reversed dispersive sorbent.It was analyzed after purification by highperformance liquid chromatography,the extraction time and the properties of the nanocomposite were optimized.Under optimized conditions,present method has linear response over concentration range of 0.5–50 ng/mL in pork samples with a satisfactory detection limit close to 0.1 ng/mL.The precisions of the current method(coefficient of variation)are lower than 5%,while recoveries are more than 98.3%.The nanocomposite exhibited high adsorptivity,long-term storage stability,satisfactory anti-interfering activity and high selectivity toward2-agonists compared with those of rGO and CNTs.