Preparation of ractopamine-tetraphenylborate complexed nanoparticles used as sensors to rapidly determine ractopamine residues in pork

In this work, we reported a simple, fast, and sensitive determination of ractopamine (RAC) residues in pork by using novel ractopamine-tetraphenylborate complexed nanoparticles (RT NPs) as sensors. The prepared RT NPs exhibited a fast response time of 10 s, a wide linear range from 0.1 to 1.0 × 10⁻⁷ mol/L, and a very low detection limit of 7.4 × 10⁻⁸ mol/L. The prepared sensor also presents a high selectivity for ractopamine under different pH conditions ranged from 2.85 to 7.18. These results reveal that the fabricated RT NPs can be used as efficient electrochemical sensors to determine ractopamine in animal productions.     

Effect of ractopamine level, gender, and duration of ractopamine on belly and bacon quality traits

The objective was to determine belly and bacon quality traits in pigs fed ractopamine (RAC) for various durations during finishing. A 2 × 3 × 2 factorial arrangement was used with barrows and gilts, fed RAC levels of 0.0, 5.0, or 7.4 ppm, for 21 or 28 d prior to harvest. Bellies were fabricated and measured for length, thickness, firmness, and processing yields. Once processed, 1.27 cm slices were removed at 25%, 50%, and 75% the distance from the blade end, packaged and digitally imaged using a Chem1 Genius² Bio Imaging System. Total slice area (TA), total slice length (TL), secondary lean length (SL), secondary lean area (SA), and percent lean area (TA – all lean components = LA) were determined by tracing images in Adobe Photoshop Elements. A composite sample from the three slices was used for proximate analysis to determine moisture and fat composition for each belly. Feeding RAC increased belly yield, TA, TL, SA, and LA (P < 0.05), but did not alter moisture or fat composition (P > 0.05). Gilts had decreased firmness and higher pump uptakes compared to barrows (P < 0.05). Additionally gilts had increased TL, SL, and LA with lower fat and higher moisture content (P < 0.05). RAC feeding duration had no significant effect on belly or bacon quality traits (P > 0.05), furthermore, no interactions were found to be significant (P > 0.05). RAC administration during finishing resulted in improved belly and bacon yields with no negative effects on the quality traits evaluated.     

Validation of an ultra-performance liquid chromatography-tandem mass spectrometry method for determination of ractopamine: Application to residue depletion study in swine

A sensitive and reliable method was developed and validated for the analysis of ractopamine in swine tissues. The sample preparation procedure was based on hydrolysis overnight, extraction with ethyl acetate, and solid-phase extraction cleanup. The target compound was determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry. The average recoveries ranged between 93.3% and 106.5%, with relative standard deviations of 7.2–12.8%. The detection and quantification limits were 0.2 and 0.5 μg/kg, respectively. The depletion profile of ractopamine was studied in healthy pigs after oral administration of feed containing 20 mg/kg ractopamine for 30 consecutive days. Ractopamine residues were still detected 11 days post-medication in all tissues examined with the exception of muscle. The highest ractopamine level was found in lung tissue. The developed method has been successfully applied to the depletion study of ractopamine in swine tissues.     

Detection of ractopamine residues in pork by surface plasmon resonance-based biosensor inhibition immunoassay

A surface plasmon resonance (SPR) biosensor inhibition immunoassay for determination of ractopamine (Rac) residue in pork was constructed by immobilising Rac derivative on the SPR-2004 biosensor chip. After extraction with perchloric acid, pork sample was cleaned by ethyl acetate and analyzed by SPR-2004 biosensor. The limit of detection (LOD) was 0.6 μg/kg for pork sample. Recoveries of Rac were higher than 80% with relative standard deviations below 10%. Although the same pretreatment was applied for both the UPLC–MS/MS and the biosensor, the biosensor showed little matrix interference by constructing pure solution and matrix-match calibration curves. Compared with Biacore Q made by Biacore AB, SPR-2004 biosensor made by Chinese Academy of Sciences which is of low cost and showed minimal matrix interferences. Accordingly, this biosensor was a promising screening instrument to be used for detection of ractopamine in supermarkets, food factories and food regulatory organisations.     

The effect of corn distiller's dried grains with solubles, ractopamine, and conjugated linoleic acid on the carcass performance, meat quality, and shelf-life characteristics of fresh pork following three different storage methods

The objective of this study was to evaluate dietary corn distiller's dried grains with solubles (DDGS), ractopamine hydrochloride (RAC), and conjugated linoleic acid (CLA) on growth performance, carcass and fat quality, and shelf-life of fresh pork from finishing pigs. Barrows (n = 72) were fed one of eight treatments consisting of two diet sources (corn-soy and corn-soy + 20% DDGS), two levels of RAC (0 and 7.4 ppm), and two levels of CLA (0 and 0.6%) for 28 days. Loins were portioned (n = 3) into one of three storage conditions (fresh, cold, frozen); each followed with seven days of retail display. Feeding RAC improved ADG and G:F (P < 0.05), whereas DDGS decreased belly fat firmness (P < 0.05). Dietary DDGS increased total polyunsaturated fatty acids in jowl and belly samples and increased Iodine Value (IV) (P < 0.05), but addition of CLA decreased IV. Dietary DDGS, RAC, or CLA had minimal impact on pork quality following varied storage methods.     

The interaction between ractopamine supplementation, porcine somatotropin and moisture infusion on pork quality

Ninety six crossbred pigs were used in a 4×2×2 experiment to determine the influence of management strategy, moisture infusion and ageing on pork quality. The treatments were i) management strategy (MS) during the last 28days pre-slaughter (Control: conventional diet; Ractopamine (Rac): porcine somatotropin (pST); and combined (Rac+pST): Rac for 28days and pST for the final 14days), ii) moisture infusion (MI) (0% and 10%) and iii) ageing period (24h and 7days). L* was decreased by pST and Rac+pST, followed by Rac and then the Control MS. Shear force was increased by Rac and Rac+pST but not by either pST or the Control MS. MI decreased L* and shear force while ageing for 7days increased L* and yellowness, and decreased drip loss and WB shear force. MI or ageing for 7days improved sensory pork quality. The results from this experiment indicated that as expected MI and ageing can be used to improve pork quality.     

Antibiotic and synthetic growth promoters in animal diets: Review of impact and analytical methods

Food quality and safety have been a significant and pressing issue in recent years. In light of the FAO's definition of food security – the physical, social and economic access to sufficient and nutritious food – food safety plays a fundamental role. Animal feed and feeding is pivotal to the livestock industry, but the use of veterinary antibiotics (VAs) and synthetic growth promoters (SGP) diminishes the sustainability of the diets and can cause an accumulation of residues in animals (meat, milk and eggs) and the environment (water and soil pollution). Wastewater systems are another major pathway through which antibiotics and hormones can enter the environment, with negative consequences. In order to protect the planet through more sustainable feeding, the reduction of antibiotics and synthetic growth promoters is a key aim, in particular with the goal of reducing antibiotic resistance and allergies. Analytical methods play a crucial role in food analysis, to determine the presence of antibiotics and other additives. Recent methods are based on liquid chromatography with ultraviolet, fluorescence, or mass spectrophotometry detection, which is recognized as an essential technique in food analysis, able to identify more than 300 compounds in feed samples. In general, a monitoring program put in place to educate the population on the hazards of residues in animal products is necessary, in conjunction with a continuous decrease in the use of antibiotics and synthetic growth promoters in animal diets.     

Effect of ractopamine–HCl supplementation for 28 days on carcass characteristics,muscle fiber morphometrics,and whole muscle yields of six distinct muscles of the loin and round

This study evaluated the effects of ractopamine–HCl (RAC) supplementation on carcass characteristics, muscle fiber morphometrics, and tenderness. Thirty-four steers (2 groups, 4 replicates) were fed RAC or carrier for 28 days prior to harvest. Seventy-two hours postmortem, the Longissimus lumborum (LL), Gracilis (GRA), Vastus lateralis (VL), Rectus femoris (RF), Semimembranosus (SM), and Adductor (ADD) were dissected from each carcass. Commodity weight, denuded weight, and muscle dimensions were collected. RAC supplementation tended to affect dressing percentage (P = 0.15) and muscle firmness (P < 0.15), and significantly affected lean maturity (P < 0.05) and marbling score (P < 0.05). With the exception of the LL and GRA (P < 0.05), RAC had no effect on muscle dimensions. RAC did not influence the tenderness of vacuum-packaged, aged steaks as measured by Warner–Bratzler shear force. Muscle fiber size within the six muscles was unchanged (P > 0.05) by RAC. Thus, RAC improves carcass parameters without a negative impact on tenderness.     

微珠芯片免疫法对肉制品中莱克多巴胺残留的检测

构建了一个基于功能化微珠表面竞争性免疫反应的流控芯片体系,在环氧化微珠表面固定小分子莱克多巴胺的蛋白全抗原,然后依次与一抗和携带荧光的二抗反应,最后输出荧光信号。在检测中,采用内标-标准曲线法,先利用标准品制作竞争性免疫反应的标准曲线,然后进行实际样本检测。该系统检测的莱克多巴胺的最低检测限达到0.03μg/L,检测时间不超过45 min。     

The effect of ractopamine hydrochloride (Paylean) on lean carcass yields and pork quality characteristics of heavy pigs fed normal and amino acid fortified diets

Effects of ractopamine hydrochloride (RAC) on carcass parameters in heavy weight (133.24 ± 8.07 kg) finishing pigs (n = 278) given amino acid fortified (AA) or 16% crude protein (CP) diets were evaluated. A total of seven experimental diets were formulated; RAC was added at 0, 5 and 20 ppm to the 16% CP diets (CP0, CP5 and CP20, respectively) and at 0, 5, 10 and 20 ppm to the AA fortified diets (AA0, AA5, AA10 and AA20, respectively). Carcass, tenderloin, and ham weights were heavier (P < 0.05) for RAC AA diets vs. AA0. Loin weight was heavier (P < 0.05) for AA20 vs. AA0 and CP20 vs. CP0. No differences (P > 0.05) were observed for color or firmness scores. Carcass muscle score, ham weight and protein% were greater (P < 0.05) for RAC diets. Moisture was greater (P < 0.05) and fat was lower (P < 0.05) for AA5 and AA20 vs. AA0 and CP5 and CP20 vs. CP0. Feeding RAC to late finishing swine increases carcass yields and protein% with lower fat% for pigs weighing up to 136 kg.