The occurrence of Listeria monocytogenes in imported ready-to-eat foods in Japan

Quantitative analyses of Listeria monocytogenes in imported ready-to-eat (RTE) foods sold at retail stores in Japan were performed. Of the 77 non-cooked meat products, 6 samples (7.8%) tested positive. The levels of contamination of 4 of the samples were below 100 colony-forming units (CFU)/g, which is the microbiological criterion for L. monocytogenes in RTE foods as determined by Codex. However, Listeria cells at levels of 100 and 400 CFU/g were detected in a salami sample and a raw ham sample, respectively. All of the 70 cheese samples and the 3 samples made from raw ham and cheese showed negative test results. These results suggest that imported RTE foods are potential sources of the causative agent of listeriosis.     

The occurrence of pathogenic Listeria monocytogenes and antibodies against listeriolysin-O in buffaloes

The occurrence of Listeria monocytogenes in meat and milk samples, and antilisteriolysin O (ALLO) antibodies in sera of buffaloes were studied. Isolation of the pathogen was attempted from the samples by selective enrichment in University of Vermont Medium and plating onto Dominguez-Rodriguez isolation agar. The pathogenicity of the isolates was tested by Christie, Atkins, Munch Petersen test and mouse inoculation test. Of 167 meat samples 2.4 and 10.17% were positive for L. monocytogenes and Listeria sp., respectively. Of the 64 milk samples 6.25 and 26.13% were positive for L. monocytogenes and Listeria sp., respectively. A total of 284 serum samples were tested by listeriolysin O (LLO)-based indirect enzyme-linked immunosorbent assay of which 25.35% were found to be seropositive. The culture positivity for L. monocytogenes and detection of ALLO did not show any agreement (kappa = 0.035). The prevalence of pathogenic L. monocytogenes in milk and meat and the occurrence of anti-LLO antibodies is of concern from the public health point of view.     

The occurrence of Toxoplasma gondii and Neospora caninum as regards meat hygiene

Toxoplasma gondii and Neospora caninum are phenotypically and phylogenetically closely related cyst-forming coccidia, both of which may cause abortion in livestock animals. T. gondii exhibits also zoonotic potential by causing diaplacental infections in the human fetus and harmful infections in immunosuppressed individuals. Humans get infected either by consuming inappropriately prepared cyst-containing meat or by ingesting oocysts originating from cat feces. Therefore, in order to assess infection risk we need to have knowledge on the prevalence of the parasite in consumable meat and thus slaughtered animals. So far, no data indicate any zoonotic potential for N. caninum. Due to its high economic impact in the bovine production in Switzerland, we included this parasite in the present study as well. The prevalence of both parasite species were investigated by PCR in muscle and brain samples of slaughtered bovines, sheep, pigs and horses. Comparatively, a serum sample from each animal was simultaneously tested serologically by a Toxoplasma-P30-ELISA and a Neospora-SA-ELISA. The prevalences determined by the T. gondii-PCR were the followings: adult cows 3%, young bulls 2%, young cows prior to gravidity 6%, calves 1%, sheep 6%, horses and pigs each 0%. For N. caninum, the PCR-prevalence was 2% for adult cows and 0% for all other animal groups. Conversely, the seroprevalences were much higher for both parasite species and all animal groups, with the exception of the fattening pigs. However, as T. gondii was principally detectable in bovine (cows and calves) as well as in sheep meat, the consumption of this meat harbours a potential infection risk for humans. In contrast, the lack of any parasite detectability in fattening pig and horse meat allows to consider this infection source as neglectable when compared to bovine and ovine meat.     

Birth weight, parturition and meat production in the dairy cow population

Birth weight was found to be closely related to calving behaviour. With all variations in Friesian dairy cattle, rising beef yield proved to be achievable even along with medium birth weight, so that calving complications and resulting decline in reproduction can be avoided.     

The occurrence of deep pectoral myopathy in broilers and associated changes in breast meat quality

1. Two experiments were conducted to determine the effect of slaughter weight on the incidence and intensity of deep pectoral myopathy (DPM) of M. pectoralis minor (p. minor muscle) in commercial conditions in Turkey and to evaluate the impact of DPM on meat quality traits of pectoralis major (p. major) muscle in broilers.

2. In Experiment 1, a total of 116 250 carcasses from 59 Ross-308 broiler flocks, classified according to slaughter weight as 2.0–2.2, 2.2–2.4, 2.4–2.6 and >2.6 kg, were evaluated for occurrence of DPM. In Experiment 2, p. major samples from unaffected broilers and each DPM stage were evaluated for meat quality, oxidant and antioxidant properties, nutritional value and fatty acid profile. DPM was characterised as 1: muscles with coagulative necrosis, 2: muscles with fibrous tissue texture and pink to plumb and 3: muscles with green necrotic area.

3. The average incidence of DPM was found to be 0.73% in Experiment 1 and independent of slaughter weight.

4. In Experiment 2, p. major muscle of broilers with DPM 1 and 2 had higher pH values with higher redness and drip loss. All DPM stages resulted in an increase in lipid content and malondialdehyde activity and lowered ash content of p. major muscle compared with unaffected birds. DPM 2 increased superoxide dismutase and glutathione peroxidase activities in M. p. major. The p. major of broilers with DPM had lower content of C18:2 conjugated linoleic and C20:3n-6 fatty acids than those of unaffected broilers. Lower Δ6 desaturase and thiosterase activities and 18:2n-6 to 18:3n-3 ratio were observed for all DPM stages compared to unaffected.

5. It was concluded that these changes obtained in p. major muscle of broilers with DPM might indicate biochemical characteristics of muscle degenerations.     

Relationships between the turnover before slaughter, welfare and the occurrence of defective DFD type meat in cattle

In this article we have presented genetic predispositions and the influence of numerous factors that occur during cattle fattening, transport and holding in slaughter plants, on their welfare and subsequently on the occurrence of defective meat, known in the literature as DFD (Dark, Firm, Dry) meat. Such meat is unwillingly bought by contemporary consumers because of its consistency and processing plants cannot intend it for production of durable processed meat due to its compliance to decay. To a great extent the occurrence of this meat defect is caused by people as a result of ignorance and incompliance of cattle welfare. It should also be remarked that there is a rising number of consumers interested in the place of origin of cattle and the way it was treated.     

Survival of sylvatic Trichinella spiralis isolates in frozen tissue and processed meat products

The ability of Trichinella spiralis larvae to survive at subfreezing temperatures encysted in the musculature of wild carnivorous mammals was assessed by evaluating motility and infectivity (to rodents) of trichinae at various intervals after storage in frozen skeletal muscle. Fifty to 60% of the larvae in grizzly bear meat were alive after storage for 27 months at -6.5 to -20 C, and 30% to 50% were still alive at 34 months. However, none survived for 38 months, on the basis of infectivity in mice and larval motility. Trichinella larvae survived up to 4 months in frozen (-6.5 to -20 C) wolverine tissue. Viable larvae were not recovered from mountain lion or fisher muscle frozen for 1 month. The effect of postslaughter processing on Trichinella larvae encysted in bear meat was evaluated by use of a similar bioassay procedure. Viability of larvae recovered from black bear meat that had been processed into ham or jerky was not affected by dry curing with a commercial salt mixture. Trichinae from both preparations induced infections in mice (58 to 90 larvae/g of tissue). However, a combination of curing and smoking was consistently lethal to encysted larvae. Viable trichinae were not recovered from ground bear meat preparations (pepperoni, salami, or sausage) processed according to commercial standards.     

Risk assessment strategies for Europe: integrated safety strategy or final product control: Example of Listeria monocytogenes in processed products from pork meat industry

The European regulation 2160/2003 of November 17th, 2003 clearly shows the European strategy of zoonosis monitoring and control as an integrated approach, including the entire food production chain with a first application to Salmonella control in different animal species. This regulation is the consequence of a risk assessment performed with a "farm to fork" philosophy. European strategy is scarcely different from the American strategy, despite the fact that both were achieved by a quantitative risk assessment, as for instance, in the USA the control of Salmonella in eggs is supposed to be completed by refrigeration. Nevertheless, the EU will still have a final product control approach towards future regulations on microbiological criteria for foodstuffs. The final production monitoring and control with HACCP (93/43/EC) and microbiological criteria is the only one available for L. monocytogenes in foodstuffs. The purpose of this paper is to discuss alternative control strategies for L. monocytogenes in pig production including integrated risk assessment. In France, most of the food-borne outbreaks associated with L. monocytogenes in delicatessen were due to one particular group of strains belonging to serovar 4b and presenting a particular RFLP/PFGE (Restriction Fragment Length Polymorphism/Pulsed Field Gel Electrophoresis) profile. The outbreak itself is always associated with the initial contamination of a RTE ("ready to eat") product and re-contamination by inappropriate handling after cooking. Consequently, in most cases the RTE product is subject to inadequate refrigeration during an excessive shelf-life. The responsibility of the food industry and the consumer is clearly engaged during this scenario of foodborne diseases. The question is how to avoid the introduction of this particular strain of L. monocytogenes in the food chain. In a study we tried to evaluate the risk of pig carcass contamination at slaughterhouse level and to identify the main risk factors associated with the infection of live pigs. In most cases inappropriate cleaning and disinfection of surfaces were associated with the contamination of raw meat, but in some cases the introduction of epidemic strains in the food chain was also associated with primary production. Feeding with soup in piggeries seemed to select a particular microbial ecology associated to L. monocytogenes contamination of live pigs. The possible strategies that may be used to control L. monocytogenes in live pig production are not yet developed sufficiently to be included in the EC regulation but should be discussed in more detail.     

Associations of the variation in the porcine myogenin gene with muscle fibre characteristics, lean meat production and meat quality traits

Pig breeding is aimed at improving lean meat production ability as well as meat quality, and muscle fibre characteristics may be important for enhancing these traits. Therefore, new molecular markers have been demanded for selecting lean meat production ability and meat quality in live animals. Myogenin belongs to the MyoD gene family, and is a candidate gene responsible for muscle fibre characteristics. We identified a new single nucleotide polymorphism (SNP) site in the 5' upstream region of the myogenin gene (nucleotides C and T). A total of 252 pigs of three breeds were genotyped by polymerase chain reaction–restriction fragment length polymorphism using BspCNI . Additionally, they were genotyped for the previously detected Msp I site in the 3'-flanking region (alleles A and B). The CCBB diplotype had the highest frequency over breeds, followed by TCBB and CCAB. The other diplotypes were not found in studied pigs. Association analysis performed for the markers found that the TCBB diplotype has desirable effects on the total number of fibres (p   < 0.002), fibre cross-sectional area (p   < 0.06), and loin eye area (p   < 0.001) than the other diplotypes. Moreover, the diplotype had the highest muscle pH value (p   < 0.07) and all meat quality traits were near the upper limit of the normal range as a reddish pink, firm and non-exudative (RFN) pork. Therefore, we suggest that selection for the myogenin diplotypes could improve total muscle fibre number, size and lean meat production ability with good meat quality.     

Review of the production of ostrich meat

Ostrich meat was originally considered to be a by-product of the leather industry. Ostrich farming focused on the production of good quality hides and was mainly based on experience. Since a few years there has been a move from hide production to meat production; however, little is known about ostrich meat production which has consequences for legislation. There is insufficient knowledge about the factors influencing muscle growth. The strong growth of ostrich meat production in the EU member states should be discussed because the climatic conditions are not optimal and the price of the meat may remain high compared to meat of broilers, pigs, and cattle. Information programmes have to be set up for all members in the production chain. The present method for stunning of ostriches has to be changed in most slaughterhouses. In this study the effects of electrical and mechanical stunning on unconsciousness, duration of unconsciousness, behaviour, and meat quality parameters were examined. At least 500 mA is needed to stun ostriches effectively, and they can be killed using a short-stick interval or a long stunning duration. A modified captive needle pistol, using air pressure, is an alternative to electrical head-only stunning.     

Epidemiological studies on the occurrence of Listeria monocytogenes in the feces of dairy cattle

Seasonal variation in the fecal shedding of Listeria spp. in dairy cattle was examined by collecting a total of 3,878 fecal samples during a period of two years. The prevalences of Listeria spp. and L. monocytogenes were higher during the indoor season (12.7% and 9.2%, respectively) than in samples collected from the animals on pasture (5.3% and 3.1%, respectively). The highest frequencies of Listeria spp. (19.4%) and L. monocytogenes (16.1%) were detected in December. Listeriae were isolated from at least one of the dairy cows from 45.8% of the 249 herds examined. 2.9% of the 314 milk samples collected from the farm bulk tanks on 80 dairy farms on four different occasions yielded L. monocytogenes. The seasonal occurrence of these bacteria in milk reflected the frequencies of Listeria in the fecal material but not those in the main roughage used; grass silage and pasture grass. Fecal material is considered to be a potential source of contamination of raw milk by L. monocytogenes. Investigation of the numbers of viable Listeria organisms in different animal fodders is considered essential in further epidemiological studies of these bacteria.     

清远市清新区肉类生产近况分析

本文对清新区近二年畜禽养猪和肉类生产情况进行了统计分析.结果表明,在非洲猪瘟影响下,与2019年相比,2020年清新区肉猪出栏减少75％,同期禽肉产量增加了6.5倍,部分填补了肉猪减产形成的肉类供应空缺.2020年1月以来,肉猪存栏缓步上升,母猪存栏数也呈现阶梯式增长;鸡和鹅的出栏和存栏则保持相对稳定.非洲猪瘟仍是本区...     

黄秋葵对肉兔生产性能、肉品质和血清生化指标的影响

为研究在饲料中添加不同量的黄秋葵对肉兔生产性能、脏器指数和血清生化指标的影响,试验选用35日龄健康新西兰肉兔120只,随机分成5组,每组3个重复,每个重复8只,预试期7 d,正试期28 d,试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组分别在基础日粮中添加1％、2％、3％和4％黄秋葵粉.结果表明:与对照组相比,试验Ⅰ、Ⅱ、Ⅲ组滴水损失率分别降低...     

哈尔滨市鲜肉中单核细胞增生性李斯特菌的分离鉴定及耐药性分析

为了解哈尔滨市单核细胞增生性李斯特茵(Lm)的污染状况及耐药状况.在哈尔滨市市场随机采集158份鲜肉样品,采用显色培养基分离,API试剂条和PCR鉴定等方法对样品中的Lm进行分离鉴定,并通过Kirby-Barer法测定分离菌株对24种抗生素的耐药性.结果从鲜肉中共分离到Lm 23株,检出率为14.56%,其中鲜猪肉检出率最高,达20.00%(14/70);23株分离菌株中耐药菌株为22株,耐药率高达95.65%.这表明哈尔滨市鲜肉中存在一定程度的Lm污染,并且分离菌株存在较严重的耐药现象.应加强控制动物饲料亚治疗抗生素的使用并严格遵守休药期,防止耐药菌株产生进而控制食源性疾病的发生.     

Immunomagnetic separation and PCR detection of Listeria monocytogenes in turkey meat and antibiotic resistance of the isolates

1. Conventional cultivation and immunomagnetic separation (IMS) cultivation methods were compared for the isolation specificity and sensitivity of L. monocytogenes from turkey meat samples. PCR was used to confirm the isolates. Disc diffusion was performed to determine the antibiotic susceptibility profiles. A total of 180 turkey meat samples collected from markets in Turkey were tested. 2. L. monocytogenes was detected in 23 samples (12.7%) by IMS and conventional cultivation. It was isolated from 16.6% (10/60), 11.6% (7/60) and 10.0% (6/60) of the meat cut, breast and leg samples, respectively. PCR assay was performed based on hlyA (LLO-listeriolysin O) gene specific primers. In all 23 (100.0%) isolates of the hlyA gene were determined. The disc diffusion test showed that 19 (82.6%) isolates were resistant to penicillin G and 17 (73.9%) to ampicillin. In addition, 8 isolates were partially resistant to erythromycin and 8 to streptomycin. 3. In conclusion, to safeguard public health turkey meat must be produced under hygienic and suitable technological conditions. Furthermore antimicrobials, as prophylactic or growth promoter agents, must be firmly controlled by governmental agencies.     

Simultaneous occurrence of selected food-borne bacterial pathogens on bovine hides, carcasses and beef meat

The aim of this study was to determine the simultaneous occurence of Salmonella spp., L. monocytogenes, verotoxigenic E. coli (VTEC), and Campylobacter spp. in slaughtered cattle and in beef meat subjected for human consumption. A total of 406 bovine hides and 406 corresponding carcasses were used to collect the samples with a swab method after exsanguination and evisceration of animals, respectively. Furthermore, 362 beef meat samples were purchased in local retail shops over the same period of time as for the bovine samples. Food-borne bacterial pathogens were identified with standard ISO methods with some modification by the use of PCR for VTEC. The isolated bacteria were then molecularly speciated (Campylobacter), serotyped (L. monocytogenes) and characterized for the presence of several virulence marker genes (VTEC and Campylobacter). It was found that 49 hide (12.1%) and 3 (0.7%) carcass samples were contaminated with more than one bacterial pathogen tested. Most of the hides were positive for Campylobacter spp. and VTEC (27 samples) and Campylobacter spp. together with L. monocytogenes (12 samples). Eight bovine hides contained L. monocytogenes and VTEC while L. monocytogenes and Salmonella spp. were detected in one sample. Furthermore, 3 pathogens (Campylobacter spp., L. monocytogenes and VTEC) were simultaneously identified in one bovine hide tested. In case of bovine carcasses 2 samples contained Campylobacter spp. and VTEC whereas one carcass was positive for L. monocytogenes and VTEC. On the other hand, 10 out of 362 (2.8%) minced beef samples were contaminated with at least two pathogens tested. The majority of these samples were contaminated with L. monocytogenes and Salmonella spp. (6 samples). It was noticed that equal number of C. jejuni and C. coli were found, irrespective of the origin of the samples. Most of the strains possessed more than one pathogenic factor as identified by PCR. Molecular serotyping of L. monocytogenes revealed that the majority of the isolates (27 out of 31; 87.1%) belonged to 1/2a serogroup. It was found that most of the VTEC isolates possessed the Shiga toxin stx2 gene (12 strains) whereas only 2 strains were str1-positive. The eneterohemolysin and intimin markers were identified only in 7 and 2 isolates, respectively. PCR analysis revealed that 4 VTEC belonged to O91 serogroup, 2 strains were O145 and 1 isolate was identified as O113. None of the VTEC detected in the study was O157 serogroup.