Animal welfare and food safety: danger, risk and the distribution of responsibility

Increased animal welfare may pose risks for public health, such as increased bacterial, viral or parasitic infections or an increased level of environmental contaminants in the food product. Examples include Campylobacter in organic boilers, Toxoplasma in pigs and poultry meat and Mycobacterium paratuberculosis in milk. Concerning environmental contaminants it is known that free-foraging laying hens will produce eggs that contain higher dioxin levels than hens kept in cages. Furthermore, outdoor chickens are considered to play an important role in the case of Avian flu outbreaks. This review indicates that it is possible to tackle each of the issues mentioned. Risk management is not only a responsibility of the government, but also should be divided amongst the participants in the food chain, including the consumer. To this end it is important that transparency about risks be maintained and optimal communication employed

Animal health in organic livestock systems: a review

Organic livestock production is a means of food production with a large number of rules directed towards a high status of animal welfare, care for the environment, restricted use of medical drugs and the production of a healthy product without residues (pesticides or medical drugs). The intentions of organic livestock production have been formulated by the International Federation of Organic Agriculture Movements (IFOAM) and were further implemented by EU regulation 2092/91 in the year 2000. The consequences of these rules for the health of the animals were not yet fully anticipated at the time these regulations were made and it has become clear that in some cases the rules are not clear enough thereby even hampering the development of the production system. In this review we shall discuss the implications of these rules for animal health, whereby we shall focus on pig, poultry and dairy production systems. Disease prevention in organic farming is based on the principles that an animal that is allowed to exhibit natural behaviour, is not subjected to stress, and is fed optimal (organic) feed, will have a higher ability to cope with infections than animals reared in a conventional way. Fewer medical treatments would thus be necessary and if an animal would become diseased, alternative treatments instead of conventional drugs should be preferred. Although homeopathy or phytotherapy are recommended according to prevailing regulations, not many organic farmers use this treatment regimen in view of lacking scientific evidence of effectiveness. Important health problems in organic livestock farming are often related to the animals’ outdoor access area. Due to such an area the animals are exposed to various viral, bacterial and parasitic infections some of which may influence the animals’ own welfare but other ones may also endanger the health of conventional livestock (e.g. Avian Influenza) or pose a food safety (Campylobacter, Toxoplasma) problem to the consumer. Many preventive measures can be taken such as using better animal breeds, optimised rearing conditions, pre-, probiotics, addition of acids to the drinking water and in case of infectious disease, tight vaccination schedules may prevent serious outbreaks

Controlling egg dioxin levels from laying hens with outdoor run

After the first news items concerning raised dioxin levels in eggs from hens with outdoor access were published in the summer of 2001, Wageningen UR carried out intensive research activities to understand the problem and to find a way to manage the problem. In 2004 the first Wageningen UR report on this issue was published. It described the possible factors that were associated with high egg dioxin levels in organic poultry farms. The most striking feature was the number of laying hens on the farm. Small and middle sized farms regularly produced eggs that exceeded the dioxin levels set out by the EU. In a follow-up study the relationship between egg dioxin levels and flock size was further analyzed and on-farm control measures were tested. Flock size was shown to be correlated with the use of the outdoor run. Two explanations were found for this observation. The first explanation is that large farms only open the barn doors late in the morning or even at the beginning of the afternoon. Small farms, on the other hand, often do not have doors at all or open them early in the morning. Furthermore, it turns out that the amount of time spent in the outdoor run is inversely related with the size of the flock. Hens from a large flock spend no more than 20% of the available time outside. The increasing scale of organic poultry systems thus already diminishes the problem with dioxin levels. Especially since large-scale organic poultry farms have a market share of 99% in The Netherlands. Various observations from the current project confirm the hypothesis that duration of outdoor run use is related to egg dioxin levels. On one farm with the same flock of hens, but kept under three different management systems, we found a direct relation between duration of outdoor run use and egg dioxin levels. Secondly, on farms where we decreased the amount of time that the hens were allowed outside and fed them inside the barn, egg dioxin levels dropped markedly. Thirdly, we noted a marked lowering of egg dioxin levels after hens were confined inside the barn due to a potential threat of aviary influenza infection from wild birds. When outside, hens pick up soil, worms and insects. The dioxins present in these are transferred very efficiently to the hens’ eggs. The longer the hens stay outside, the higher the intake from these sources, which results in high egg dioxin levels. Historical pollution of the soil with dioxins is the main cause of dioxin in the eggs of hens kept in outdoor runs. We found a clear correlation between dioxin levels in soil and in eggs from chickens kept on this soil. This project showed that replacing contaminated soil with fresh sand resulted in a marked drop in the egg dioxin levels. Although worms and other micro fauna could contribute to the egg dioxin levels, we still do not know what the relative contribution from these sources is as compared to the contribution from soil uptake. The knowledge that was gained with this project can now be used to efficiently control egg dioxin levels in poultry with outdoor access, by taking measures mainly directed at the duration of outdoor run use. Thanks to these measures and the introduction of a dioxin monitoring protocol, dioxin levels can nowadays be managed quite easily. Small organic enterprises still need some attention, as they generally do not take part in the dioxin monitoring protocol, due to economic reasons. Their market share however, is less than 1%

Effect of rodent control on Toxoplasma gondii infections in animal friendly pig farms with a rodent problem.

Livestock farming can be prone to rodent infestations as it provides unlimited amounts of shelter, water and food to commensal rodents. Besides economic losses and structural damages, these rodents may transmit pathogens directly to farmers or via livestock to consumers of livestock products. Hygienic standards in intensive pig production systems have largely eliminated the contact between rodents and livestock. The introduction of animal-friendly production sytems may however lead to an increased contact between livestock and small mammals (both rodents & insectivores). This has led to a demand for rodent control methods that are in line with ecologic principles. To underline the necessity of appropriate rodent control in animal-friendly farming systems we used the tranfer of an important food-borne pathogen, Toxoplasma gondii, as an example. Using lightcycler PCR methods we showed that rodents on animal-friendly farms indeed harbored Toxoplasma gondii. Subsequently three farms with a rodent problem were chosen to investigate the effect of an intense rodent control campaign on the seroprevalence of Toxoplasma infection of slaughtered pigs. During the time period July 2006 to January 2007 rodent control campaigns were started on these three farms and all consecutive slaughtered pigs were tested for the presence of Toxoplasma antibodies. Toxoplasma seroprevalence on all three farms dropped during the rodent control campaign. Further research is needed to exactly find out which rodent or insectivore species form the largest risk for transfer of Toxoplasma infection and which control method is most appropriate to target these species. This project thus shows that rodent control needs extensive attention in animal friendly farming systems. Although extermination of rodents is possible using methods that are in line with organic principles we would like to stress the importance of prevention. Rodent prevention includes measures such as making the direct environment of the barns unattractive for rodents, closing cracks and openings of the barn to limit access of rodents, closing feed storage and using natural predators in the vicinity of the farm (predatory birds). Inappropriate rodent control is not only a problem that concerns organic farming, but should be addressed in any livestock system where increased contact between wildlife and farm animals is possible

The role of rodents and shrews in the transmission of Toxoplasma gondii to pigs

Inadequate rodent control is considered to play a role in Toxoplasma gondii infection of pigs. This issue was addressed in the current study by combining a 4-month rodent control campaign and a 7-month longitudinal analysis of T. gondii seroprevalence in slaughter pigs. Three organic pig farms with known rodent infestation were included in the study. On these farms, presence of T. gondii in trapped rodents was evaluated by real-time PCR. All rodent species and shrews investigated had T. gondii DNA in brain or heart tissue. Prevalence was 10.3% in Rattus norvegicus, 6.5% in Mus musculus, 14.3% in Apodemus sylvaticus and 13.6% in Crocidura russula. Initial T. gondii seroprevalence in the slaughter pigs ranged between 8% and 17% and dropped on the three farms during the rodent control campaign to 0–10%, respectively. After 4 months of rodent control, T. gondii infection was absent from pigs from two of the three farms investigated and appeared again in one of those two farms after the rodent control campaign had stopped. This study emphasizes the role of rodents and shrews in the transmission of T. gondii to pigs and the importance of rodent control towards production of T. gondii-free pig meat

Challenges for avoiding and handling disease problems in organic herds

Disease prevention in organic farming is based on the principles that an animal that is allowed to exhibit natural behaviour, that is not subjected to stress and that is fed optimal (organic) feed, will have a higher ability to cope with infectious insults than animals reared in a conventional manner. Less treatments would thus be necessary and if an animal would become diseased, alternative treatments instead of conventional drugs should be preferred. Homeopathy or phytotherapy are recommended according to the prevailing regulations. The presumptions mentioned above have not yet been substantiated by scientific evidence. No data are available showing that disease prevalence of animals held under organic conditions is lower than under conventional conditions. Furthermore, to date, no proper scientific evidence is available concerning the efficacy of homeopathic remedies in farm animals. Only few reports are available concerning the use of phytotherapy in the management of sick animals. At present consumers are ignorant about these issues, but one should be aware of the fact that the postponing of proper treatment to a diseased animal may cause a severe negative impact on the “consumer” image of organic livestock production. Important health problems in organic farming are often related to the outdoor access of the animals. Due to the availability of an outdoor area the animals are confronted with various viral, bacterial and parasitic infections of which some may influence the animals own welfare but others may also endanger the health of the conventional livestock (Avian Influenza) or pose a food safety (Campylobacter, Toxoplasma) problem to the consumer

Control of the risk of human toxoplasmosis transmitted by meat

One-third of the human world population is infected with the protozoan parasite Toxoplasma gondii. Recent calculations of the disease burden of toxoplasmosis rank this foodborne disease at the same level as salmonellosis or campylobacteriosis. The high disease burden in combination with disappointing results of the currently available treatment options have led to a plea for more effective prevention. In this review we describe Toxoplasma as a hazard associated with the consumption of undercooked meat or meat products and provide an analysis of the various options to control the risk of human toxoplasmosis via this source. Monitoring and surveillance programs may be implemented for pre-harvest control of Toxoplasma infection of farm animals, with the reduction of environmental oocyst load as the most important milestone. Alternatively, Toxoplasma safe meat can be obtained through simple post-harvest decontamination procedures, whereby freezing the meat may currently be the best option, although new technologies using irradiation or high-pressure treatment may offer promising alternatives. Influence of culture, religion and food handling customs may predispose a certain type of meat as an important source of infection, indicating that prevention needs to be tailored according to social habits in different regions in the world. The rationale for more stringent control measures to prevent toxoplasmosis both from disease and economic points of view is emphasized

The ethics of rodent control

Because western societies generally see animals as objects of moral concern, demands have been made on the way they are treated, e.g. during animal experimentation. In the case of rodent pests, however, inhumane control methods are often applied. This inconsistency in the human-animal relationship requires clarification. This paper analyses the criteria that must be met when judging the use of animals during experiments, and investigates whether these can be applied in rodent control. This is important, because, until now, animal welfare has been less of an issue in pest control: effectiveness, hygiene and cost efficiency have been leading principles. Two options are available to solve the inconsistency: the first is to abandon the criteria used in animal experimentation; the second is to apply these criteria to both animal experimentation and rodent control. This latter option implies that rodent control methods should not lead to intense pain or discomfort, and any discomfort should have a short duration and should allow escaped rodents to lead a natural life. Adherence to this option will, however, require a shift in the design of rodent control methods: effectiveness will no longer be the leading principle. It will have to share its position with animal welfare and humaneness