Comparison of different devices for predicting the lean meat percentage of pig carcasses

Lean meat percentage (LMP) is the criterion for carcass classification and it must be measured on line objectively. The aim of this work was to compare the error of the prediction (RMSEP) of the LMP measured with the following different devices: Fat-O-Meat’er (FOM), UltraFOM (UFOM), AUTOFOM and VCS2000. For this reason the same 99 carcasses were measured using all 4 apparatuses and dissected according to the European Reference Method. Moreover a subsample of the carcasses (n = 77) were fully scanned with X-ray Computed Tomography equipment (CT). The RMSEP calculated with cross validation leave-one-out was lower for FOM and AUTOFOM (1.8% and 1.9%, respectively) and higher for UFOM and VCS2000 (2.3% for both devices). The error obtained with CT was the lowest (0.96%) in accordance with previous results, but CT cannot be used on line. It can be concluded that FOM and AUTOFOM had better accuracy than UFOM and VCS2000.     

Lean content prediction in pig carcasses,loin and ham by computed tomography (CT) using a density model

Pig carcasses (122 half carcasses, 52 hams and 52 loins) from the Spanish pig population, were obtained in a commercial slaughterhouse and scanned by computed tomography to generate a predictive model determining weight and lean content. The model is mainly based on a density correction equation. The weight prediction model used the area of the histogram of the whole half carcass in a range of − 250 to + 800 Hounsfield units added to 2769 g corresponding to the average weight of the head and pig feet that have not been scanned. The lean content predictive model is based on the ratio between the area of the lean peak in the calculated histograms and the area of the histogram of the whole half carcass. Both models were correlated with a manual dissection of the samples. Results from the predictive models and from the dissection were compared with the calculation of the root mean square error of calibration (RMSEC) for weight determination and lean content. Results show that a RMSEC of 0.6 kg can be obtained for the weight half carcass. For prediction of the lean meat percentage a RMSEC of 1.48% can be obtained for the carcasses, 0.97% for the ham and 1.07% for the loin. According to our results, with a simple methodology it is possible to have good prediction values of weight and lean percentage in accordance with EU regulation.     

Lean meat prediction with HGP, CGM and CSB-Image-Meater, with prediction accuracy evaluated for different proportions of gilts, boars and castrated boars in the pig population

Prediction equations for the percentage lean meat in pig carcasses in The Netherlands were derived for the Hennessy Grading Probe 7, Capteur Gras/Maigre — Sydel and CSB-Image-Meater. Because castrated males are expected to vanish from the Dutch pig population in the near future, accuracy of prediction was evaluated for different scenarios representing a wide range of different proportions for entire males, castrated males and females in the Dutch pig population. The prediction equations for the instruments are in compliance with the EC regulations for prediction accuracy for the different scenarios. So, these equations will remain valid when castrated males are (gradually) removed from the Dutch slaughter population. Results of this study are of interest for researchers from countries or areas contemplating the use of one of the aforementioned instruments. The statistical approach for evaluation of prediction accuracy is of particular interest when changes in proportions of important subpopulations in the target population are foreseen.     

Determination of the lean meat percentage of pig carcasses using magnetic resonance imaging

The purpose of Workpackage 3 of the European Eupigclass project was to test indirect methods of measuring the lean meat percentage of a carcass that would be less costly, at least as accurate and more consistent than dissection. Magnetic resonance imaging was one of the three indirect methods tested to measure the lean meat weight and the lean meat percentage of pig carcasses, the other methods being X-ray CT and vision techniques. One hundred and twenty carcasses from three different genotypes and from both sexes were slaughtered. The left parts of the carcasses were fully dissected and the right parts were investigated with an indirect method using a 1.5T MRI system. The acquisition protocol was chosen to give an optimized contrast between fat and muscle tissues. Two different approaches, image segmentation and PLS regression, were used to extract information from the images. Automatic image segmentation was performed to quantify the volume of muscle in the images and gave a standard error of prediction using a linear regression with the dissection of the left half carcasses of 586 g and 1.10% for lean meat weight and lean meat percentage, respectively. PLS regression using the signal intensities histograms gave an estimation error of 465 g for lean meat weight. These results showed that MRI could be used in place of full dissection for authorizing and monitoring classification equipment of pig carcasses.     

猪胴体瘦肉率仪器测定值与生猪品种等级的关系研究

使用PG100瘦肉率测定仪,对四种不同品种等级的生猪屠宰后的胴体的瘦肉率进行了测定,并与精确分割试验测定的瘦肉率进行了比较。结果表明使用仪器测定的瘦肉率指标,能够较好地反映生猪品种等级的优劣,可以用于生猪屠宰过程中的智能分级。     

北京地区三元杂交猪胴体的分级优化

为了提高猪胴体分级的准确性,利用计算机视觉技术、图像处理技术及统计分析方法,对已建立的猪胴体分级标准及预测方程进行修订.结果表明:以左半胴体质量、臀中肌横长和臀中肌膘厚预测瘦肉率绝对误差小于4%;同时以瘦肉率、臀中肌膘厚、1/2横长处膘厚及6~7肋处膘厚等特征作为分级主要参数,使分级准确率达90%.将各处膘厚与瘦肉率相结合,并对猪胴体级别根据实际需求进行调整,可使分级工作更加合理,准确性也有提高.     

Evaluation of three ultrasound instruments, CVT-2, UltraFom 300 and AutoFom for predicting salable meat yield and weight of lean in the primals of pork carcasses

Three commercially available ultrasound instruments were evaluated using pigs representative of the Canadian pig population: CVT-2, UltraFom 300 and AutoFom. The reflectance probe HGP2 was utilized as the baseline instrument. Sampling was stratified by fat thickness. The original data set (n=236) was divided randomly into a calibration set (n=194 [85 barrows and 109 gilts]) to calibrate the instruments and a validation set (n=72[32 barrows and 40 gilts]) for validating the calibration models. For salable meat yield, RMSE values for the calibration models were: HGP2, 1.56; CVT-2, 1.57; UltraFom, 1.70; and AutoFom, 1.68. For lean (kg) in butt, picnic, loin and ham, and weight (kg) of the skinless, trimmed belly, RMSE for the calibration models was similar for all four instruments: respectively, 0.19–0.21, 0.21–0.23, 0.31–0.37, 0.35–0.40 and 0.35–0.36 kg. Validation results for predicting salable meat yield show that the improvement in precision and/or accuracy associated with the UltraFom 300 or AutoFom, over the baseline reflectance probe HGP2, was negligible whereas a definite advantage was observed for the CVT-2. However, validation results for predicting kg of lean in the primals did not show any clear advantage for the three commerciallly available ultrasound instruments over the baseline reflectance probe HGP2.

Calibration and validation procedures showed that, if one was to base the assessment of these three ultrsound instruments uniquely on the precision and accuracy for predicting salable meat yield and/or kg of lean in the primals, any amelioration over the baseline reflectance probe HGP2 would have to be viewed as rather negligible; particularly for the UltraFom 300 or AutoFom.     

Prediction of lean meat content in pork carcasses using the Hennessy Grading Probe and the Fat-O-Meater in Argentina

Rapid evolution of pork production in Argentina requires new calibrations for predicting carcass lean meat percentage with the Fat-O-Meater (FOM) and Hennessy Grading Probe (HGP), first adopted in 1995. The second objective was to unify the lean percentage units with those applied by the European Union. Carcasses of 59 gilts and 56 barrows from different environments and breeds were tested. Carcass weights were from 65 to 117kg, and lean content was from 38% to 62%. Predicting lean content by multiple regression equations, the coefficients of determination R(2) were 0.801 and 0.794 for the FOM and HGP equations, and the residual standard deviations (RSD) were 2.40% and 2.45%, respectively. Both instruments had the same precision and were accurate enough to be adopted in national carcass grading classification. Hot carcass weight was not selected as a significant variable. The same prediction equations could be used for gilts and barrows. Quadratic terms did not improve predictions.     

猪胴体预冷过程中雾化增湿与喷淋对干耗的影响差异性研究

本研究对比了雾化增湿与雾化喷淋两种方式对猪胴体预冷干耗的影响。采用超声雾化加湿器来增加预冷环境湿度方式以及气液两相流间歇雾化喷淋的方式分别对猪胴体样品进行预冷处理,以直接冷却猪胴体样品为对照组。实验结果表明:雾化增湿组样品最终平均干耗为1.442%,经14 h雾化喷淋处理的各样品继续冷却至24 h后测得最终平均干耗为1.066%,对照组实验样品最终平均干耗为2.914%。雾化喷淋冷却处理与雾化增湿冷却处理均可使猪胴体冷却速度加快(p<0.05)。雾化喷淋冷却处理与雾化增湿冷却处理均可有效缩短样品干耗达到峰值的时间(p<0.05),其达到峰值时间关系为:雾化喷淋组<雾化增湿组<对照组。雾化喷淋冷却处理与雾化增湿冷却处理均可显著降低猪胴体预冷干耗(p<0.05);雾化喷淋冷却处理比雾化增湿冷却处理降低干耗效果更为理想(p<0.05)。      

基于猪胴体影像分级仪的我国商品猪瘦肉率预测方程的建立

为了能够准确预测我国商品猪的胴体瘦肉率,完成生猪的在线快速分级、快速结算,最终实现优质优价,研究运用CSB-Image-Meater 猪智能化影像分级仪,挑选436 头不同类型的商品猪测定其瘦肉率、热胴体质量、背膘厚度和肌肉厚度等指标。通过多元线性逐步回归建立基于CSB-Image-Meater 的预测商品猪瘦肉率的回归方程。结果表明：瘦肉率预测方程y=61.264 － 0.583xl +0.173x2(xl 为猪胴体臀中肌处的最薄膘厚度(F 值),x2 为臀中肌末端到脊髓管边缘处垂直距离(R 值),校正决定系数R2 为0.87,残差标准差RSD 为2.31%),作为CSB-Image-Meater 猪智能化影像分级仪的瘦肉率测定模型,拟合程度较好。方程预测值与实际值差异不显著,方程预测准确率较高,效果良好,完全可以应用于实际生产中。     

The effects of dietary oregano oil supplementation on pig meat characteristics

The effects of different concentrations of dietary oregano essential oil supplementation on finishing pig meat characteristics were investigated in the present study. Thirty-two barrows and thirty-two gilts were divided into four equal groups. During the experimental period, which started when the animals were 5 months old and finished after 35 days, the first group was fed the control diet (group C), whereas the other three groups consumed the same diet, with the only difference that the feed was supplemented with oregano essential oil at concentrations of 0.25, 0.5 and 1 ml/kg of fed diet (groups OR1, OR2 and OR3, respectively). At the end of the experiment, pigs were fasted for 12 h, weighed and slaughtered. After overnight chilling, a 50 cm loin section was removed from the half of the carcasses (8 pigs per nutritional treatment; 4 barrows and 4 gilts) and transported to laboratory for further examination.     

Characteristics of Staphylococcus hyicus strains isolated from pig carcasses in two different slaughterhouses

In a previous study, we showed that coagulase positive staphylococci, which are often used as indicators for Staphylococcus aureus, are frequently found on pig carcasses. Further characterization of the strains identified only a minor part as S. aureus. Selected non-S. aureus strains were all identified as Staphylococcus hyicus, However, two studies described in this species strains that produce staphylococcal enterotoxins. The aim of the present study was to further characterize such coagulase positive S. hyicus strains isolated from pig carcasses and to assess the results for their food safety relevance. A total of 189 strains from two abattoirs were characterized. Phenotypically, 98.9% showed non-pigmented colonies, 99.5% no haemolysis and 67.7% were egg yolk-positive. DNase activity was found in all but one isolate. Only five of the 189 strains were resistant to the antimicrobials tested. One strain harboured the mecA gene. Exfoliative toxin genes were detected in 31 (16.4%), S. aureus enterotoxin genes in none of the strains.The PFGE genotyping results show only a limited number of clusters. Cluster I included more than 50% of the strains. The fact that similar or closely related PFGE patterns of S. hyicus can be found on carcasses after bleeding in both abattoirs indicates the occurrence of widespread strains in the Swiss pig population. Moreover, the genotyping results revealed a remarkable homogeneity in S. hyicus strains isolated from different process stages in abattoir B, which could indicate a recontamination problem with persisting strains.     

The effects of two alleles of IGF2 on fat content in pig carcasses and pork

The different fat infiltration capabilities of two alleles of IGF2 (G3072A) have been investigated in pigs of a Landrace-Large White × Duroc cross. Paternally inherited G allele carrier pigs show an increased content of adipose rich meat cuts such as the lard or the belly and 4 mm larger backfat thickness values. Paternally inherited A carrier pigs on the other hand contain larger muscle tissue rich cuts such as the loin, the ham and the tenderloin and have 0.19 units lower feed conversion index. No substantial differences have been found neither in intramuscular fat content in several muscles nor in meat quality in both pig groups. Hams of paternally inherited G carrier pigs are richer in both subcutaneous adipose tissue (23.1 vs 19.1 mm backfat thickness) and intermuscular fat content. The suitability and the economics of using any of the two of both genotypes for cured ham production are discussed.     

Comparison of the lipid content and fatty acid composition of intermuscular and subcutaneous adipose tissues in pig carcasses

Lipid contents and compositions were measured in 35 pigs from seven genotype-sex groups with large variations in body composition. The animals were slaughtered at 115kg live weight, and the left side was separated into four primal cuts: belly, ham, loin, and shoulder. Samples of adipose tissues were taken from flare fat and from subcutaneous and intermuscular adipose tissues in each of the four cuts. In the loin, the outer and inner layers of subcutaneous adipose tissue were sampled separately. Total lipid content was lower in intermuscular than in subcutaneous adipose tissue. It was the highest in flare fat. There was a gradient of decreasing unsaturation from the outer layer of subcutaneous adipose tissue, to the inner layer, to intermuscular adipose tissue, to flare fat. The monounsaturated fatty acid concentrations followed the same pattern. There was a statistically positive correlation between the linoleic acid concentration of the different adipose tissues and the half carcass muscle content.     

Microbiological contamination of pig and cattle carcasses in different small-scale Swiss abattoirs

A total of 750 pig carcasses and 535 cattle carcasses from 17 small-scale abattoirs were sampled by excision at four sites (pig: neck, belly, back, ham; cattle: neck, brisket, flank, rump). Samples were examined for total viable counts (TVC) and Enterobacteriaceae. Mean TVCs ranged from 2.4 to 4.2 log(10)CFUcm(-2) on pig carcasses and from 2.7 to 3.8 log(10)CFUcm(-2) on cattle carcasses. With regard to EU Regulation (EC) No 2073/2005, TVCs were mainly considered satisfactory (pig: 81.3%; cattle: 71.4%). Amongst sites, the back (pigs) and neck (cattle) tended to yield higher TVCs. Enterobacteriaceae were detected in low counts on 23.9% of pig carcasses and 21.7% of cattle carcasses. Amongst abattoirs, Enterobacteriaceae prevalence on pig and cattle carcasses ranged from 2.0% to 56.0% and from 0.0% to 55.0%, respectively. Consequently, criteria of the EU Regulation proved to be a suitable tool for the appraisal of microbiological results (TVCs) from pig and cattle carcasses from small-scale abattoirs. Because the occurrence of Enterobacteriaceae on carcasses was too infrequent to ensure log normality, frequencies should be compared for these organisms.     

Quantification of muscle, subcutaneous fat and intermuscular fat in pig carcasses and cuts by magnetic resonance imaging

The aim of this study was to determine the suitability of magnetic resonance imaging (MRI) to predict tissue composition of pig carcasses and cuts. Twenty-four pig carcasses were cut into the four primary cuts that were analyzed with a low field MRI imager before a total dissection. Images were then processed to identify and quantify pixels representing muscle, subcutaneous fat and intermuscular fat fractions. MRI provided a good prediction of muscle content in cuts and carcasses, with R² ranging from 0.970 to 0.997. The prediction was slightly less accurate for total fat (0.951 ? R² ? 0.986) or subcutaneous fat (0.918 ? R² ? 0.994). Finally, the prediction of intermuscular fat content in considering intermuscular fat classified pixels was acceptable only for the belly (R² = 0.837).     

Detection and characterization of Salmonella in lairage, on pig carcasses and intestines in five slaughterhouses

In this study, conducted at five slaughterhouses, individual pigs were sampled and followed up from stunning to cooling down of the carcasses. In this way, Salmonella prevalence and possible risk points were described. At the lairage area, pens were sampled using overshoes. At stunning and bleeding, pigs were individually identified and subsequently swabs were taken of the oral cavity and the carcass after polishing, splitting and forced chilling. Additionally, duodenum, ileum, rectum and mesenteric lymph nodes were extracted and samples were taken of the scalding water. All samples were submitted to Salmonella isolation and Salmonella isolates were serotyped and genotyped by pulsed-field gel electrophoresis (PFGE). Of all samples taken (n = 1953), 14.1% were Salmonella positive. The prevalence of S. in the lairage area varied widely (from 0 to 100%) between the slaughterhouses. Of the sampled pigs (n = 226), 48.2% were positive in at least one sample. Statistical analysis revealed that the contamination of the lairage area was related to a higher amount of positive carcasses after polishing. Furthermore, the contamination of the carcasses after splitting and forced chilling was related to the contamination level of the carcass after polishing. A relation between the outer (carcass) contamination and the inner (gut content and lymph nodes) contamination of a pig could not be established. The predominant serotypes were S. Typhimurium (58.7%) and S. Derby (17.4%). Genotyping revealed 46 different PFGE profiles among the 276 Salmonella isolates. The same genotype at the lairage area as in the oral cavity of the pigs was found in 95%. The results indicate that the lairage area is a primary source of Salmonella in slaughter pigs and that carcass contamination originates from the environment rather than from the pig (inner contamination) itself. It further shows that slaughterhouses vary in their capability of dealing with Salmonella positive pigs. A slaughterhouse specific approach is needed, however, general guidelines should be provided to decrease the contamination level of the lairage area and the slaughter environment.     

A comparison of the carcase characteristics of pigs immunized with a ‘gonadotrophin-releasing factor (GnRF)’ vaccine against boar taint with physically castrated pigs

Evaluating the effect of using a GnRF vaccine against boar taint on the carcase characteristics of boars, vaccinated pigs were compared with physically castrated. In total, 554 male pigs were randomly assigned to treatment groups. T01 comprised physically castrated pigs in the first week of life, T02 comprised pigs vaccinated twice before slaughtering. There was neither significant difference between the groups in terms of average liveweight nor in the hot carcase weight. The mean dressing percentage was 1.5% higher for T01 than for T02 (P < 0.0001). The lean meat percentage was significantly higher in T02 (P < 0.0001). Backfat and backmuscle thickness were significantly higher in T01 (P < 0.0001 and P = 0.0099, respectively). Within the EUROP grading vaccinated pigs were in favour (P = 0.0034). There were no significant differences using the AutoFOM system: weights of the boned ham, boned shoulder and loin (P = 0.5102, P = 0.8881 and P = 0.1919, respectively). The weight of the belly was significantly higher (P = 0.0042) in T01 while the lean meat percentage of belly was significantly higher (P < 0.0001) in T02.