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

Multifunctional one-droplet microfluidic chemosensing of ractopamine in real samples: a user-oriented flexible nano-architecture for on-site food and pharmaceutical analysis using optical sensors

Illegal use of ractopamine (RAC) in the food industry has dire consequences for health which should be curbed by inexpensive on-site checks. In this study, four advanced nanostructures of AuNPs were examined for this purpose. For the first time, a novel cost-effective colorimetric opto-sensor based on gold nanoparticles in aqueous solution was developed and successfully utilized for the recognition of RAC in real samples. The colorimetric chemosensor based on AuNPs-CysA exhibited a linear range of 0.1 μM to 0.01 M with a limit of detection (LOD) of 0.001 μM. Also, using AuNPs-DDT as a photonic probe two ranges of linearity of 0.01 to 50 μM and 0.005 to 0.01 M were obtained (LOD = 1 nM). The outstanding features of the utilized nanostructures are the simple preparation, the suitable stability of AuNPs-CysA and the excellent selectivity of AuNPs-DDT toward RAC recognition. Finally, the engineered colorimetric systems were combined with a simple and inexpensive optimized microfluidic glass fiber-based device. This work paves the way for devising inexpensive and efficient on-site recognition devices for food safety checks.

Glucometer-based biosensor for the determination of ractopamine in animal-derived foods using rolling circle amplification

Screening for persistent organic pollutants (POPs) in food is a complex and challenging process, as POPs can be present in very low levels and can be difficult to detect. Herein, we developed an ultrasensitive biosensor based on a rolling circle amplification (RCA) platform using a glucometer to determine POP. The biosensor was constructed using gold nanoparticle probes modified with antibodies and dozens of primers, magnetic microparticle probes conjugated with haptens, and targets. After competition, RCA reactions are triggered, numerous RCA products hybridize with the ssDNA-invertase, and the target is successfully transformed into glucose. Using ractopamine as a model analyte, this strategy obtained a linear detection range of 0.038-5.00 ng mL^-1 and a detection limit of 0.0158 ng mL^-1, which was preliminarily verified by screening in real samples. Compared with conventional immunoassays, this biosensor utilizes the high efficiency of RCA and the portable properties of a glucometer, which effectively improves the sensitivity and simplifies the procedures using magnetic separation technology. Moreover, it has been successfully applied to ractopamine determination in animal-derived foods, revealing its potential as a promising tool for POP screening.

d-Penicillamine functionalized dendritic fibrous nanosilica (DFNS-DPA): synthesise and its application as an innovative advanced nanomaterial towards sensitive quantification of ractopamine

During the twentieth century, ractopamine (RAC) as one of the important and frequently used feed additives and doping agents has attracted considerable attention in the animal breeding industry and sports competitions.

New Insights in Muscle Biology that Alter Meat Quality

Fresh meat quality is greatly determined through biochemical changes occurring in the muscle during its conversion to meat. These changes are key to imparting a unique set of characteristics on fresh meat, including its appearance, ability to retain moisture, and texture. Skeletal muscle is an extremely heterogeneous tissue composed of different types of fibers that have distinct contractile and metabolic properties. Fiber type composition determines the overall biochemical and functional properties of the muscle tissue and, subsequently, its quality as fresh meat. Therefore, changing muscle fiber profile in living animals through genetic selection or environmental factors has the potential to modulate fresh meat quality. We provide an overview of the biochemical processes responsible for the development of meat quality attributes and an overall understanding of the strong relationship between muscle fiber profile and meat quality in different meat species.

AgNPs/QDs@GQDs nanocomposites developed as an ultrasensitive impedimetric aptasensor for ractopamine detection

Developing easy-to-use and miniaturized sensors for in-field monitoring of targets which is related to human health is necessary. Ractopamine (RAC) is a feed additive with serious side effects that is forbidden in many countries. This study reports the fabrication of an impedimetric aptasensor for ultrasensitive and selective detection of the RAC in human biological fluids. Accordingly, an efficient nanocomposites was synthesized by a beneficial combination of graphene quantum dots (GQDs), quantum dots (QDs) and silver nanoparticles (AgNPs) for modifying a glassy carbon electrode (GCE). This nanocomposite is promising to present a synergistic effect in the increase of the active surface area of the modified electrode to more load the biocapture of the target. Next, the RAC-binding aptamer (Apt) was attached to the AgNPs/QDs@GQDs/GCE surface and a sensitive layer for the RAC detection was embedded. A RAC-Apt complex was formed upon adding the RAC and the changes of the electrochemical behavior were studied by some electrochemical techniques such as electrochemical impedance spectroscopy (EIS). Under optimal conditions, the charge transfer resistance (R_ct) value was increased linearly with increasing of the RAC concentrations in the range of 1 fM to 901.4 nM. Limit of detection (LOD) was calculated to be 330 aM which is superior by other reported electrochemical methods in the RAC sensing. The applicability of the aptasensor was tested in human urine and blood serum as the real samples and satisfactory results of specificity were achieved. It seems that the proposed strategy not only provides a new ultrasensitive strategy for RAC detection but also expands the application of the sensing interface to develop other aptasensors by changing the Apt sequence.

Metabolism of glycerol in pigs fed diets containing mixed crude glycerin and β-adrenergic agonist

The optimised use of mixed crude glycerin (MCG) and ractopamine hydrochloride (RH) in diets for finishing pigs requires a better understanding of glycerol metabolism. Therefore, the present study evaluated the performance, blood parameters, metabolite concentrations in the Longissimus lumborum muscle and the activity of enzymes in the liver, subcutaneous adipose tissue and kidney of pigs fed diets containing MCG and/or RH. According to the initial weight, 64 barrows were distributed in a 4 × 2 factorial design, corresponding to four concentrations of MCG (0, 100, 150, and 200 g/kg) in diets containing 0 or 10 mg/kg of RH. There was no MCG × RH interaction for any of the evaluated parameters (P > 0.05). Moreover, there was no isolated effect of dietary MCG or RH on the weight gain and the blood concentrations of glucose, insulin, triacylglycerols, total cholesterol, total protein, albumin, creatinine, cortisol and lactate (P > 0.05). There was a higher rate of phosphorylation of glycerol in the liver, stimulation of lipogenesis in adipose tissue and a likely increase in the utilisation of glycerol by muscle fibres in response to an increased concentration of circulating glycerol from the diet (P < 0.05). In contrast, when the diet contained up to 200 g/kg MCG and 10 mg/kg RH, there were indications of a lower utilisation of glycerol for the synthesis of triacylglycerols in muscle, liver and adipose tissue, in addition to increased oxidation of amino acids in the liver followed by improved feed conversion of pigs (P < 0.05).

Determination of ractopamine and salbutamol in pig hair by liquid chromatography tandem mass spectrometry

A liquid chromatography tandem mass spectrometric method was developed for the determination of two β-agonists (ractopamine and salbutamol) in pig hair samples. An isotope of ractopamine-d5 or salbutamol-d6 as an internal standard was used to carry out quantitative analysis. Concentrated sodium hydroxide was used to pretreat hair samples and then purified by the solid phase extraction (SPE) procedure. The extracted solution was evaporated and reconstituted for injection in the instrument with electrospray ionization (ESI) operating in a positive multiple-reaction-monitoring (MRM) mode. Ractopamine and salbutamol separation were performed on C18 analytical column under gradient condition. The internal standard calibration curve was linear in the range of concentration from 0.5 to 100 ng mL⁻¹ (R² > 0.995). Recoveries of this method estimated at three spiked concentrations of 100, 250 and 500 ng mL⁻¹ in pig hair samples, were 79–82% for ractopamine and 77–96% for salbutamol. The corresponding inter-day and intra-day precisions expressed as relative standard deviation (RSD %) were 3.8–6.4% and 3.8–8.6%, respectively. The analytical time for one sample was 8 min. The detection limit of this method was 0.6 and 8.3 ng mL⁻¹ for ractopamine and salbutamol, respectively. This developed method can be applied for monitoring the use of the β-agonists salbutamol and ractopamine in swine feed incurred pig hair.

A review of heavy weight market pigs: status of knowledge and future needs assessment

Marketing weight is an important economic variable that impacts the productivity and profitability of finishing pig production. Marketing weight has been increasing worldwide over the past decades driven by the dilution of fixed production cost over more weight per pig and the improvement of genetic selection of lean-type pigs. This review was aimed to summarize current knowledge and assess the future research needs on producing finishing pigs with marketing weight greater than 130 kg. Based on a thorough literature review, increasing marketing weight affected overall pig growth; in particular, cumulative average daily gain (ADG) decreased by 4.0 g, average daily feed intake (ADFI) increased by 78.1 g, and gain-to-feed ratio (G:F) decreased by 0.011 for every 10 kg increase of marketing weight. Increasing marketing weight by 10 kg increased carcass yield by 0.41% units, backfat by 1.8 mm, longissimus muscle (LM) area by 1.9 cm², carcass length by 2.2 cm, and belly yield by 0.32% units, but decreased percentage of fat-free-lean by 0.78 units and decreased loin, shoulder, and ham yields by 0.13, 0.16, and 0.17% units, respectively. Studies that investigated the effects of marketing weight on pork quality observed decreased pH by 0.02 and 0.01 at 45 min and 24 h postmortem, respectively, and increased a* value by 0.28 per 10 kg marketing weight increase. Heavier market pigs had increased concentrations of saturated fatty acids and intramuscular fat. However, studies reported conflicting results for L* and b* values, drip loss, Warner-Bratzler shear force, and sensory properties of pigs in response to increasing marketing weight. A limited amount of research has been conducted to estimate nutrient requirements for pigs greater than 140 kg. Increased weight and size of heavy pigs can create challenges to farm and packer facilities and equipment. Discussions and recommendations are provided concerning the adjustments for floor and feeder space, barn design, ventilation, disease control, transportation, and carcass processing needed for increasing marketing weight. In conclusion, increasing marketing weight creates both opportunities and challenges to current finishing pig production, and future research is needed to provide nutritional and management guidelines and improve feed efficiency and meat quality of heavy weight market pigs.

Molecularly Imprinted Membrane Electrospray Ionization for Direct Sample Analyses

Typically dealing with practical samples with very complex matrices, ambient ionization mass spectrometry suffers from low detection sensitivity. In this study, molecular imprinting technology was explored and integrated with the membrane electrospray ionization (MESI) method for direct sample analyses. By enriching targeted analytes on molecularly imprinted membranes (MIMs), improvement (by 10- to 50-fold) in the limit of quantitation could be achieved, compared to conventional nanoelectrospray ionization methods or other ambient ionization methods. MIMs were prepared by cross-linking a synthesized molecularly imprinted polymer layer onto a polyvinylidene difluoride (PVDF) membrane. The characteristics of MIM in recognizing target analytes were investigated and verified. Experiments showed that MIM-ESI could provide satisfactory performances for direct quantification of targeted analytes in complex samples using mass spectroscopy (MS), and the quantitative performance of this methodology was validated. With the capability of target enrichment, the uses of MIM-ESI MS in different application fields were also demonstrated, including food safety, quantification of drug concentrations in blood, pesticide residues in soil, and antibiotic residues in milk.

Simultaneous detection of clenbuterol and ractopamine based on multiplexed competitive surface enhanced Raman scattering (SERS) immunoassay

In this work, we demonstrate a competitive surface-enhanced Raman scattering (SERS) immunoassay for multiplexed detection of clenbuterol and ractopamine.

Ractopamine with dietary lysine concentrations above basal requirements of finishing barrows improves growth performance, carcass traits and modifies the mTor signalling pathway

A 28-day study was conducted to evaluate the effects of three step-up levels of ractopamine hydrochloride (RAC) together with two additional levels of standardised ileal digestible lysine (Lys) above the basal requirements on growth performance, carcass characteristics and the mechanism of action on adipose and muscle tissue. In all, 108 finishing pigs (initial bodyweight 75.37 kg ± 2.88) were used for growth data and 54 pigs for carcass data. Samples from 18 pigs were used for the molecular study. Pigs were blocked by initial bodyweight and allotted to one of the following nine treatments: negative control (NC) without addition of RAC or Lys supplementation, constant 7.5 mg/kg RAC, 5 mg/kg RAC for 14 days, followed by 10 mg/kg for 14 days (Step-up 1), 5 mg/kg RAC for 21 days, followed by 10 mg/kg for 7 days (Step-up 2) and 5 mg/kg RAC for 7 days followed by 10 mg/kg for 21 days (Step up 3); on constant and step-up treatments were added 15% or 30% Lys above the basal level, giving a 4 × 2 + 1 factorial with six replicates. Loin muscle and fat tissue were collected for carcass-characteristic analysis and western blotting for p-AKT, p-P70S6K and carnitine palmitoyltransferase I. Feeding RAC increased gain to feed ratio and efficiency of energy utilisation (EF) from Day 0 to Day 13 (P < 0.05) compared with NC. From Day 14 to Day 27, greater average daily gain (ADG) was observed in RAC-treated animals (P < 0.05), except in the Step-up 2 with 30% additional Lys. During the second half of the trial, RAC positively affected ADG, gain to feed ratio and EF (P < 0.01), while a Step-1 versus Step-2 effect was observed for ADG (P < 0.03). For the overall period, RAC-treated pigs had greater ADG than did NC pigs (P < 0.05). An average of 8.1% improvement on feed efficiency and 30% improvement on EF were observed for RAC-fed pigs in comparison to NC pigs (P < 0.05). Chilled carcass weight and loin eye area were increased in pigs fed RAC (P < 0.01). Western blotting showed greater p-P70S6K in muscle samples from pigs fed RAC with 15% additional Lys than in those from NC pigs (P < 0.10). RAC was effective at improving efficiency of production. Lys supplementation of 15% was enough for optimal performance of the pigs in the present study; however, step-up programs did not outperform RAC-constant programs. Results of the present study suggest that RAC stimulates protein synthesis through the mTOR signalling pathway.

Ham and belly processing characteristics of immunological castrated barrows (Improvest) fed ractopamine hydrochloride (Paylean)

Effects of sex class (physically castrated, PC or immunologically castrated, IC) and diet (0 or 5mg/kg ractopamine hydrochloride, RAC) on characteristics of ham and bellies were determined from pigs slaughtered in three groups with similar ending live weights. One carcass per pen per marketing group (n=8) was selected to evaluate further processing characteristics. Data were analyzed as a 2×2 factorial design with a split plot in time and fixed effects of sex, diet, marketing group, and their interactions. IC fresh bellies were thinner (P<0.01) and softer (P<0.01) than PC bellies. IC hams and bellies were leaner (P<0.05) than those from PC pigs. RAC feeding did not affect (P>0.05) fresh ham or belly characteristics but decreased (P<0.01) fat in cured PC bellies. Marketing group affected (P<0.05) fresh quality, processing characteristics, and composition of hams and bellies. Immunological castration and RAC produced leaner finished products but did not alter processing yield of hams or bacon.

Label free electrochemical aptasensor for ultrasensitive detection of ractopamine

A label free electrochemical (EC) aptasensor for ultrasensitive detection of ractopamine (RAC) was developed. A special immobilization media consisting of gold nanoparticles/poly dimethyl diallyl ammonium chloride-graphene composite (AuNPs/PDDA-GN) was utilized to improve conductivity and performance of the biosensor. The RAC aptamer was attached on AuNPs of the composite membrane via Au-S bond. The fabrication process of the EC aptasensor was characterized by electrochemical impedance spectroscopy and cyclic voltammetry. The peak currents obtained by differential pulse voltammetry decreased linearly with the increasing of RAC concentrations and the sensor responds approximately logarithmically over a wide dynamic range of RAC concentration from 1.0 × 10(-12)mol/L to 1.0 × 10(-8)mol/L. The linear correlation coefficient of the developed aptasensor was 0.998, the limit of detection was 5.0 × 10(-13)mol/L. The proposed EC aptasensor displayed good stability, reproducibility and robust operation in animal urine. Particularly, the generality of the fabrication approach of electrochemical aptasensor is highlighted with a further example for illegal drugs detection via the aptamer identification.

Desempenho e rendimento de carcaça de suínos na fase de terminação, recebendo dietas com diferentes níveis de ractopamina

ResumoO objetivo com este trabalho foi avaliar o desempenho e o rendimento de carcaça de suínos na fase de terminação de machos castrados e fêmeas, recebendo dietas contendo diferentes níveis de ractopamina. Foram utilizados 60 animais, com peso inicial de 84,27 ± 2,26kg, aleatoriamente distribuídos para uma das seis dietas experimentais compostas por diferentes níveis de ractopamina (zero; três; seis; nove; 12 e 15ppm) e cinco repetições por tratamento. Ao final do período experimental, foi avaliado o efeito dos diferentes níveis de ractopamina sobre o peso final (PF), consumo de ração médio diário (CRMD), ganho de peso médio diário (GPMD), conversão alimentar (CA) e rendimento de carcaça. Observou-se aumento linear (P<0,05) para peso final e ganho de peso médio diário, à medida que houve aumento dos níveis de ractopamina. Para a conversão alimentar (P<0,05), evidenciou-se decréscimo de 25,50% nos animais que receberam 15ppm de ractopamina na dieta. Para o consumo de ração médio diário e rendimento de carcaça, não foram observados efeitos significativos (P>0,05). A adição de ractopamina na dieta de suínos machos castrados e fêmeas em terminação proporcionou melhor desempenho aos animais, promovendo melhoras nos parâmetros produtivos.

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.

Effects of diet mix time and ractopamine hydrochloride on finishing pig growth and carcass performance

Two experiments were completed to determine the effects of diet mix uniformity and ractopamine HCl on finishing pig performance. In Exp. 1, a total of 200 pigs (BW = 90 kg) were used in a 33-d growth assay arranged in a randomized complete block design with 5 pigs/pen and 8 pens/treatment. Treatments were a corn-soybean meal-based control diet mixed for 360 s or the mixed control diet with 10 mg/kg ractopamine added before additional mixing for 0, 30, 120, or 360 s. Chromium was added to the diet and analyzed to determine mix uniformity of the ractopamine. Therefore, this experiment was designed to determine the effects of nutrient utilization from a thoroughly mixed diet with a potentially nonuniform distribution of ractopamine. Pigs fed diets with ractopamine had greater (P < 0.05) ADG, G:F, final BW, HCW, dressing percentage, loin depth, and percentage carcass lean with lower (P = 0.005) 10th rib backfat thickness. Increasing mix time from 0 to 360 s decreased (quadratic, P = 0.001) CV for Cr from 67 to 12% but had no effect on the response to ractopamine for any growth or carcass measurements. In Exp. 2, a total of 160 pigs (BW = 93 kg) were used in a 27-d growth assay arranged in a completely randomized design with 2 pigs/pen and 16 pens/treatment. Treatments were a corn-soybean meal-based control diet mixed for 360 s or the control diet with 10 mg/kg ractopamine mixed for 0, 30, 120, or 360 s. Diet mix uniformity was determined by measuring Cr and using Quantab Cl titrators (low range 0.005 to 0.1% as NaCl; Environmental Test Systems Inc., Elkhart, IN) to measure the concentration of salt. This experiment was designed to determine the combined effects of potentially nonuniform distribution of both nutrients and ractopamine. The use of ractopamine increased (P < 0.05) ADG, G:F, final BW, HCW, dressing percentage, percentage lean, and loin depth. Increasing mix times from 0 to 360 s decreased (quadratic, P = 0.050) CV for salt and Cr from 51 to 12% and 51 to 15%, respectively, with no effect on ADG, ADFI, final BW CV, HCW, dressing percentage, backfat thickness, loin depth, or percentage carcass lean; however, G:F tended to increase (linear, P = 0.07) as mix time increased from 0 to 360 s. In conclusion, increasing mix time of diets from 0 to 360 s did not affect the response of finishing pigs to ractopamine

Effects of feeding ractopamine hydrochloride (Paylean) to physical and immunological castrates (Improvest) in a commercial setting on carcass cutting yields and loin quality

Effects of feeding ractopamine (RAC; 5 mg/kg) to physically castrated (PC) and immunologically castrated (IC) pigs on carcass characteristics, cutting yields, and loin quality were evaluated using 285 carcasses. Male pigs were randomly assigned to sex treatments (PC and IC) at birth and fed the same nursery diets before allotment into 32 pens with 22 pigs per pen in a grow-finish barn. Pigs in the PC group were physically castrated at approximately 5 d of age, and pigs in the IC group were administered Improvest at 11 and 18 wk of age. Diet treatments (control or RAC) were initiated on study d 87. Pigs were marketed at 12 d (4.5 wk post-second Improvest dose), 19 d (5.5 wk post-second Improvest dose), and 33 d (7.5 wk post-second Improvest dose) following the start of final diet treatments. Three carcasses per pen were selected for evaluation of cutting yields and loin quality. Data were analyzed using PROC MIXED in SAS with fixed effects of sex, diet, market group, and their interaction; carcass (N = 285) was the experimental unit. Carcasses from RAC-fed pigs were heavier (P < 0.01) and had deeper (P = 0.02) loins than control-fed carcasses. Carcasses from IC pigs were similar (P = 0.22) in weight but had less (P < 0.01) fat and shallower (P = 0.02) loins when compared to PC carcasses. There were differences (P < 0.05) among market groups for carcass weights, fat depths, loin depths, and estimated carcass leanness. For cutting yields, RAC-fed carcasses had greater (P ≤ 0.03) bone-in lean and total carcass cutting yields than control-fed carcasses while there were no differences (P > 0.05) between RAC-fed and control-fed carcasses when evaluating LM color, marbling, firmness, pH, drip loss, and tenderness. Carcasses from IC pigs had greater (P < 0.05) boneless lean yields, bone-in lean yields, and total carcass cutting yields than PC carcasses. There were minimal differences (P < 0.05) in LM marbling, firmness, composition, and tenderness between PC and IC pigs. There was an interaction (P = 0.03) between sex and diet for LM composition. Control-fed PC loins had more (P < 0.01) lipid than all other treatment combinations. Market group had effects (P < 0.05) on carcass cutting yields, LM color, marbling and firmness scores, pH, purge loss, composition, and tenderness. The results from this study indicated RAC and immunological castration were additive in terms of improving carcass cutting yields while having minimal effects on pork quality.

Effects of feeding ractopamine hydrochloride (Paylean) to physical and immunological castrates (Improvest) in a commercial setting on growth performance and carcass characteristics

Growth performance and carcass characteristics of physically castrated (PC) and immunologically castrated (IC) pigs fed ractopamine hydrochloride (RAC; 5 mg/kg) were evaluated in 64 pens of 22 pigs each. Male pigs were randomly assigned to castration method at birth. Pigs in the PC group were physically castrated at 5 d of age while IC pigs were administered Improvest at 11 and 18 wk of age. Pigs entered the grow-finish barn at approximately 9 wk of age (d 0). Dietary treatments (control or RAC) were initiated on d 87. Final treatment arrangement was a 2 × 2 factorial of castration method and diet. Data were analyzed using a mixed model with fixed effects of castration method, diet, market group, and all 2- and 3-way interactions. Pen was the experimental unit. From d 0 to 65, IC pigs had 11.2% greater (P < 0.01) G:F and 11.6% less (P < 0.01) ADFI than PC pigs, but ADG was increased 1.0% in PC pigs compared with IC pigs (P < 0.01). From d 65 to 87, IC pigs had 7.9% greater (P < 0.01) ADG and 12.1% greater (P < 0.01) G:F than PC pigs while having similar (P = 0.16) ADFI. At the initiation of diet (RAC) treatments, BW of all treatments were similar (P ≥ 0.32). From d 87 to 120 (RAC feeding period), IC pigs had 10.0% greater (P < 0.01) ADG and 10.5% greater (P < 0.01) ADFI than PC pigs while having similar (P = 0.64) G:F. Feeding RAC increased (P < 0.01) ADG by 16.9% and G:F by 17.9% while having no effect (P = 0.42) on ADFI from d 87 to 120. There were no significant interactions between castration method and diet on growth performance from d 87 to 120. For the entire study (d 0-120), IC pigs had 2.6% greater (P < 0.01) ADG, 4.6% less (P < 0.01) ADFI, and 7.3% greater (P < 0.01) G:F than PC pigs. Averaged over market groups, IC pigs were 2.5 kg heavier (P < 0.01) and had similar (P = 0.10) carcass weights and 1.8 percentage units less (P < 0.01) dressing yields than PC pigs. Additionally, IC pigs had 1.3 mm less (P < 0.01) fat and 1.7 mm less (P < 0.01) loin depth than PC pigs. Pigs fed RAC were 2.9 kg heavier (P < 0.01) and had 2.3 kg heavier (P < 0.01) carcasses and 2.2 mm deeper (P < 0.01) loins but similar (P = 0.21) dressing yields and tended (P < 0.10) to have 0.4 mm less fat than control-fed pigs when averaged over market groups. Group 3 pigs were the heaviest (P < 0.01) at slaughter and had the heaviest (P < 0.01) carcasses, greatest (P < 0.01) dressing yields, and the most (P < 0.01) carcass fat of all market groups. Overall, immunological castration and RAC were additive in terms of improving growth performance and carcass characteristics.

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 7.4ppm), and two levels of CLA (0 and 0.6%) for 28days. 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.

Evaluation of additional cooking procedures to achieve lethality microbiological performance standards for large, intact meat products

The U.S. Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) has a specific lethality performance standard for ready-to-eat products. To assist meat processing establishments in meeting the performance standard, USDA-FSIS developed Appendix A, which provides guidelines for cooking temperatures, times, and relative humidity. This project determined whether the USDA-FSIS performance standards for lethality were met when using parameters other than those identified in Appendix A to cook large hams and beef inside rounds. The effects of alternative lethality parameters on the reduction of Salmonella Typhimurium and coliforms and on the toxin production of Staphylococcus aureus were evaluated. Large (9- to 12-kg) cured bone-in hams (n = 80) and large (8- to 13-kg) uncured beef inside rounds (n = 80) were used in this study. The products were subjected to 1 of 10 treatments defined by combinations of final internal product temperatures (48.9, 54.4, 60.0, 65.6, or 71.1°C) and batch oven relative humidities (50 or 90 % ). For all treatments, at least a 6.5-log reduction in Salmonella Typhimurium was achieved. The coliform counts were also substantially reduced for both hams and rounds. Across all treatments for both products, S. aureus toxin production was not detected. The relative humidity did not alter the lethality effectiveness for any of the treatments. The final internal temperatures and relative humidity combinations used in this project achieved the lethality performance standard established by USDA-FSIS for fully cooked, ready-to-eat products.