Assessment of organoleptic postmortem inspection techniques for bovine offal

Objective To evaluate organoleptic postmortem inspection techniques for bovine livers and kidneys.
Study design At Australian export abattoirs, bovine liver and kidneys are assessed and graded by qualified meat inspectors during normal operations. Over a 12-month period at a large abattoir in eastern Australia during 1997 and 1998, a sample of these organs was reassessed independently using a range of pathological and microbiological methods. Agreement between routine inspection and independent assessment was evaluated using methods of inter-rater agreement.
Results A total of 944 livers and 1374 kidneys were included in the study. All of these organs had been classified during routine inspection. The authors examined 363 livers and 329 kidneys both grossly and histologically, including 36 livers and 14 kidneys that were also subjected to microbiological examination. All other organs were only examined grossly. There was only a moderate level of agreement between the routine and independent assessment methods. For livers, the percentage agreement was 80.2%, McNemar's test of symmetry 55.2 (3 degrees of freedom, P < 0.001) and kappa 0.63. For kidneys, the percentage agreement was 67.8%, McNemar's test of symmetry 9.9 (1df, P = 0.002) and kappa 0.35.
Conclusions The results reinforce concerns from a number of authors about organoleptic postmortem inspection. Risk assessment methodologies offer the opportunity to modify inspection techniques in a manner that is most relevant to current public health concerns.     

Risk-based evaluation of postmortem inspection procedures for pigs in Australia

The results of traditional (incision) and risk-based (visual) postmortem inspection procedures were compared on groups of approximately 30,000 pigs. The performance characteristics used as a basis for comparison included the non-detection rates of grossly detectable abnormalities, the microbiological contamination rates of carcases and boned product, the association of reactive lymph nodes with carcase condemnation and the achievement of 'finished product standards' for 'wholesomeness'. It was estimated that 6 per cent of all cases of abscessation and 28 per cent of all cases of arthritis were undetected by the traditional method, and the comparable figures for the risk-based procedure were 19 per cent and 39 per cent. However, when the rates of contamination of undetected abnormalities with foodborne hazards and other carcase contamination parameters were taken into account, it was concluded that both inspection systems were likely to result in a very similar level of consumer protection. Any increase in potential exposure to foodborne hazards in the abnormalities undetected by risk-based inspection would be insignificant in comparison with the potential exposure to foodborne hazards resulting from contaminated 'normal' lymph nodes and carcase surfaces. There were no statistically significant differences between the two procedures in the contamination rates of pre-chill carcases or boned retail products with Salmonella and Yersinia species.     

A risk-assessed evaluation of postmortem meat inspection procedures for ovine thysanosomiasis

A risk assessment model was used to evaluate 4 meat inspection procedures for routine detection of Thysanosoma actinioides, a tapeworm that commonly infests the bile duct system of adult sheep in the United States. The overall sensitivities of different procedures ranged from 11.96 to 58.70%, and the nondetection rates per 1,000 viscera sets that passed inspection ranged from 38 to 77. On the basis of performance attributes for each procedure produced by the risk assessment model, the consumer was exposed to an aesthetic defect that was in 9 to 17 of every 1,000 livers passed for human consumption. The amount of wastage was also identified (3 to 39 livers/1,000 passed). Viewing of the incision site of the common hepatic duct was the most preferable routine inspection procedure, and matched pair analysis revealed that there was no additional benefit in combining this procedure with routine expression of a portion of bile from the gallbladder.     

Comparison of two different meat inspection techniques

Field studies of meat inspection procedures in three different slaughter houses were performed in Germany, in 1996. In total 22,634 fattening pigs from 63 farms were inspected twice, using a visual and the traditional (mandatory inspection system) procedure. Statistical analysis was performed using the rate of ND+ (Non-Detected Positives) for both visual and traditional inspection. Neither the visual nor the traditional methods detected all lesions which were supposed to be in the lot of animals inspected. Some of the results could be explained by the nature and obviousness of the respective lesion. Conclusions regarding the future performance of inspection should not be drawn before a formal risk analysis procedure for the particular lesion has been done.     

Causes and implications of bovine organs/offal condemnations in some abattoirs in Western Nigeria

Food animals though sources of protein and revenue to man, also serve as vehicles of disease transmission. This work reviews a three year record of slaughtered cattle in 12 abattoirs/slaughter slabs in western Nigeria to determine the economic and public health issues associated with their disease conditions. Out of 641,224 cattle slaughtered, 51,196 (7.98%) were attributable to 14 diseases/conditions including tuberculosis, pneumonia, fascioliasis, pimply gut, paramphistomosis, cysticercosis, dermatophilosis, tonsillitis, taeniasis, ascariosis, abscess, mange, mastitis and immature fetuses. Pneumonia (21.38%), fascioliasis (20.28%) and tuberculosis (7.95%) were major reasons for condemnations; least being ascariosis (0.01%). The lungs (45.66%) and liver (32.94%) accounted for most organ condemned while the heart (0.02%) was the least affected. The proportions of pneumonia, fascioliasis and immature fetuses observed were not statistically different (Mean = 3895.7; 3654.0; 3467.3); however, a significant difference existed with other conditions (Mean_A = 3895.7; 3654.0; 3467.3; Mean_B = 1359.7; 1057.7; 510.3). Organs/offal condemnations constituted loss of revenue and animal protein as 124,333 kilogrammes worth of meat valued in Naira at N41,613,043 (332,904) was lost over the period giving an average of N13,871,014 (332,904) was lost over the period giving an average of N13,871,014 (110,968) annually. This, coupled with fetal wastage represented an economic loss; with associated public health implications.     

Sarcomere length influences postmortem proteolysis of excised bovine semitendinosus muscle

The interaction between sarcomere length and postmortem proteolysis as related to meat tenderness is not clear. The extent of thick and thin filament overlap alters actomyosin binding and may alter substrate availability during aging-induced tenderization. The objective of this study was to determine the influence of sarcomere length on proteolytic degradation in beef. Strips from bovine semitendinosus were either stretched 40% and restrained or allowed to shorten unrestrained in an ice bath. After rigor completion, 0.6-cm cross sections were fabricated and were randomly assigned to 2, 4, 7, or 10 d of aging treatments. Myofibrils were isolated for sarcomere length determination. Samples were collected and frozen for shear force analysis, and muscle proteins were extracted for SDS-PAGE and Western blotting analyses to determine troponin T (TnT) proteolysis. Sarcomere length was greater (P < 0.01) in stretched muscle samples compared with shortened samples (2.57 vs. 1.43 microm, respectively). Correspondingly, shear force values were greater (P < 0.05) in shortened samples than stretched samples. Western blots revealed the presence of 3 major intact TnT bands that diminished with time postmortem and 4 bands (TnT degradation products) that accumulated during postmortem storage. Quantification of intact TnT showed increased (P < 0.05) proteolysis at 4 and 7 d postmortem in samples with long sarcomeres. By 10 d, only traces of the greatest molecular weight intact TnT band were evident in both shortened and stretched samples, suggesting this TnT band may be more susceptible to proteolysis than other intact TnT bands. Degradation products of TnT appeared earlier postmortem in samples with long sarcomeres. The 30-kDa TnT fragment appeared after 7 d of postmortem storage in samples with long sarcomeres but not until 10 d in muscle containing short sarcomeres. Collectively, these data show that postmortem TnT proteolysis is sarcomere length-dependent and suggest that thick and thin filament overlap may influence the postmortem aging process in beef.     

Tropical fish medicine. Biopsy and rapid postmortem techniques for diagnosing diseases of fish

Biopsy and rapid postmortem techniques are simple to perform with commonly available instruments. Because the skin and gills are the target organs for so many infectious agents, biopsy is a very useful tool in pet fish medicine. The major requisite for successful diagnosis using biopsy materials is the ability to recognize different taxonomic groups of pathogens. Many of these pathogens may be present in clinically normal individuals, and their importance must be interpreted with other clinical findings. Rapid postmortem techniques can identify several common systemic diseases affecting pet fish. The usefulness of these procedures is highly dependent on the state of tissue preservation of the specimens presented.     

3项实验综合检验判定病死肉

在肉品卫生质量检验中,鉴别病、健肉有很多种理化方法,通过多年的研究及多方面的探讨,我们于1997年初开始引进原解放军农牧大学科研成果-动物性食品兽医卫生检验箱中的病死畜禽肉综合检验技术,经过实验室对照试验及小区试验,最后在全省范围内推广.     

Comparison of postmortem techniques for the detection of Mycobacterium bovis in white-tailed deer (Odocoileus virginianus).

A retrospective study of various diagnostic postmortem techniques used in a 4-year surveillance program for detection of Mycobacterium bovis infection in wild white-tailed deer (Odocoileus virginianus) was conducted. The tests evaluated were routine histopathology, acid-fast staining, detection of acid-fast bacilli in culture, and an M. tuberculosis group-specific genetic probe applied to pure cultures. Each of these techniques were compared with a reference or "gold standard" of mycobacterial culture and identification. Histopathology, the most rapid form of testing for M. bovis infection in white-tailed deer samples, had a sensitivity of 98% and a specificity of 87%, resulting in a positive predictive value of 94%. The detection of acid-fast bacilli by staining was less sensitive than histopathology (90%), but its higher specificity (97%) resulted in a positive predictive value of 99%. The detection of acid-fast bacilli on culture was both highly specific (93%) and sensitive (100%). The group-specific genetic probe had the highest sensitivity and specificity and produced results in complete agreement with those of mycobacterial culture, suggesting that this technique could be used as the new "gold standard" for this particular wildlife tuberculosis surveillance program.     

Subpopulations of bovine lymphocytes separated by rosetting techniques

A combination of E-rosetting techniques with both neuraminidase- and AET-treated sheep erythrocytes (RBC) was used to enumerate subsets of bovine T lymphocytes. Direct (anti-Ig) rosetting procedures were used to enumerate B lymphocytes bearing surface immunoglobulin (Ig). Approximately 10% of bovine peripheral blood lymphocytes formed rosettes only with neuraminidase-treated RBC; 20% formed rosettes with either neuraminidase- or AET-treated RBC; 30% formed rosettes only with AET-treated RBC; 25% possessed surface Ig, as shown by rosette formation with anti-Ig-coupled RBC; and the remaining 15% lacked both E receptors and surface Ig. These five populations were physically separated by centrifugation on Ficoll-Diatrizoate and recovered for functional analysis. The procedures reported here should be useful for the identification of lymphocyte populations responsible for recognition, effector, and cooperative functions in the bovine immune system.     

Assessment of producer conducted antemortem inspection of market pigs in Australia

OBJECTIVE: A field trial was conducted to evaluate the effectiveness of on-farm antemortem inspection performed by Australian pig producers in terms of proficiency in detecting unhealthy animals (suspects), the impact on food safety and animal welfare outcomes. ANIMALS: A total of 64 trial groups of market pigs (n = 10,703) were dispatched from 20 herds to three abattoirs in three states. PROCEDURE: All producers and abattoir antemortem inspectors were trained in antemortem inspection prior to the trial, using a standardised set of antemortem criteria. Study 1 consisted of three comparisons: on-farm versus abattoir antemortem inspections on the same pigs, transport effects in suspect and normal pigs, and meat rejection and carcase disposition in suspect and normal pigs. Study 2 compared Salmonella spp. status of suspect and normal pigs. Studies 3 and 4 were conducted to assist the interpretation of the results of on-farm versus abattoir inspection. Antemortem inspection results of three producers and one abattoir antemortem inspector were compared with those of a reference inspector (Gold Standard). RESULTS: Of the pigs examined, 2.12% (95% CI: [1.84%, 2.42%]) were classified as suspect at on-farm antemortem inspection compared to only 0.14% at abattoir antemortem inspection. Forty one percent of pigs classified as suspect on-farm had locomotor problems (arthritis, lameness and foot abscess). Compared to normal pigs, suspect pigs had a relative risk of 67.7 (P < 0.0001) of suffering transport injuries. Meat rejection amounted to the equivalent of 9.68% of suspect carcases, compared to the equivalent of 0.35% of normal carcases. The isolation of Salmonella species from caecal content from 20.9% of 67 suspect pigs and 18.8% of 133 control pigs (two matched healthy pigs from the same batch for each suspect pig) were not significantly different. When compared with the reference inspector on-farm, three producers classified abnormalities in 2495 pigs with high specificity (0.98), acceptable sensitivity (0.82) and kappa (0.57). CONCLUSIONS: With training, producer sensitivity in antemortem inspection may be high and more proficient than abattoir antemortem inspection. Use of producer inspections may have benefits for animal welfare and chain efficiency, but not food safety.     

Assessment of producer conducted antemortem inspection of market pigs in Australia

OBJECTIVE: A field trial was conducted to evaluate the effectiveness of on-farm antemortem inspection performed by Australian pig producers in terms of proficiency in detecting unhealthy animals (suspects), the impact on food safety and animal welfare outcomes. ANIMALS: A total of 64 trial groups of market pigs (n= 10,703) were dispatched from 20 herds to three abattoirs in three states. PROCEDURE: All producers and abattoir antemortem inspectors were trained in antemortem inspection prior to the trial using a standardised set of antemortem criteria. Study 1 consisted of three comparisons: on-farm versus abattoir antemortem inspections on the same pigs, transport effects in suspect and normal pigs, and meat rejection and carcase disposition in suspect and normal pigs. Study 2 compared Salmonella spp status of suspect and normal pigs. Studies 3 and 4 were conducted to assist the interpretation of the results of on-farm versus abattoir inspection. Antemortem inspection results of three producers and one abattoir antemortem inspector were compared with those of a reference inspector (Gold Standard). RESULTS: Of the pigs examined, 2.12% (95% CI: 1.84%, 2.42%) were classified as suspect at on-farm antemortem inspection compared to only 0.14% at abattoir antemortem inspection. Forty one percent of pigs classified as suspect on-farm had locomotor problems (arthritis, lameness and foot abscess). Compared to normal pigs, suspect pigs had a relative risk of 67.7 (P < 0.0001) of suffering transport injuries. Meat rejection amounted to the equivalent of 9.68% of suspect carcases, compared to the equivalent of 0.35% of normal carcases. The isolation of Salmonella species from caecal content from 20.9% of 67 suspect pigs and 18.8% of 133 control pigs (two matched healthy pigs from the same batch for each suspect pig) were not significantly different. When compared with the reference inspector on-farm, three producers classified abnormalities in 2,495 pigs with high specificity (0.98), acceptable sensitivity (0.82) and kappa (0.57). CONCLUSIONS: With training, producer sensitivity in antemortem inspection may be high and more proficient than abattoir antemortem inspection. Use of producer inspections may have benefits for animal welfare and chain efficiency, but not food safety.     

Assessment of defined antigens for the diagnosis of bovine tuberculosis in skin test-reactor cattle

The continued use of purified protein derivative (PPD) tuberculin is considered to be the main factor which limits the specificity of diagnostic tests for bovine tuberculosis (TB). This study evaluated a whole blood interferon-gamma (IFN-gamma) assay and compared the diagnostic potential of PPD with two tuberculosis-specific antigens, ESAT-6 and MPB70. To provide estimates of sensitivity and specificity, responses were measured in 180 skin test-reacting cattle, of which 131 were confirmed as tuberculous, and in 128 cattle from TB-free herds. For the skin test reactors, there was a positive correlation between the IFN-gamma responses to PPD from Mycobacterium bovis (PPDB) and PPD from Mycobacterium avium (PPDA), indicating cross-reactivity between these complex antigens which are the basis of the skin test. In comparisons of the ESAT-6 IFN-gamma test with a PPD IFN-gamma test (using PPDB compared with PPDA), there was a decrease in sensitivity (76.3 per cent vs 89.3 per cent), but a clear increase in specificity (99.2 per cent vs 92.2 per cent). The provision of high specificity, even with lower sensitivity, offers major benefits for testing in areas with a low incidence of TB.     

Comparison of three culture techniques for the isolation of Brucella abortus from bovine supramammary lymph nodes

Three different culturing techniques were compared and evaluated to determine the most effective method for isolating Brucella abortus from bovine supramammary lymph nodes (SM's). In method I, the SM was sliced in half, and the inner surface was minced finely with a sterile scalpel. The minced surface was spread onto the agar surface of 4 selective media. In method II, the SM was cut into small pieces and placed in a bag with a volume of phosphate-buffered saline equal to the volume of the lymph node. The bag was placed in a laboratory blender and the SM was macerated for 5 min. The tissue suspension was spread with a sterile cotton swab onto the agar surface of 4 selective media. In method III, the SM was processed in the laboratory blender. One milliliter of the suspension was pipetted into a flask of biphasic medium, and 2 ml of the suspension was pipetted into another flask of biphasic medium. A total of 626 SM's from 285 cows were cultured. Brucella abortus was isolated from 149 (52.3%) cows by 1 or more methods. Brucella abortus was isolated from 136 cows by method I. 137 cows by method II, and 86 cows by method III. Nine (3.2%) cows were positive by method I only, 11 (3.9%) cows by method II only, and 2 (0.7%) cows by method III only. The isolation rate for method III was significantly lower than for method I or II. There was no significant difference between methods I and II.