No difference in paratuberculosis seroprevalence between organic and conventional dairy herds in the Netherlands

Purpose. Paratuberculosis or Johne’s disease in cattle is considered to play a role in the pathogenesis of Crohn’s disease in humans. Whether organic production may influence the prevalence of paratuberculosis in dairy herds was not known until now and was therefore the purpose of our study. Methods. Blood samples were taken in 2003 from cows older than three years, originating from 76 organic dairy herds. Samples were tested for antibodies against Mycobacterium paratuberculosis using an ELISA. Data were compared with a similar analysis performed by the Animal Health Service on 579 dairy farms participating in the National Dutch Paratuberculosis Program, which includes a few organic herds. Results. The mean number of animals tested was 48 and 56 for the organic versus the control group, respectively. Of the 3688 organic sera tested, 43 revealed the presence of M. paratuberculosis antibodies. These seropositive animals originated from 22 farms (28.9 %). Fourteen farms (18.4 %) only had one seropositive animal. Two farms had 6 seropositive animals. In the control group 197 farms had seropositive animals (34 %), which was not statistically significant from the organic farms. In the control group 107 farms only had one seropositive animal (18.5 %), which was also not different as compared to the organic group. Conclusions. These data show that the incidence of Johne’s disease is not different between organic and regular dairy herds. The slightly higher incidence in the control group may be due to the fact that the number of animals tested per farm was larger. Grants: This study was supported by a grant (LNV program-PO-34) from the Dutch Ministry of Agriculture, Nature and Food Qualit

Towards sustainable management of rodents in organic animal husbandry

From 26 to 28 May 2004 an international seminar was held in Wageningen, the Netherlands, about current knowledge and advice on rodent management on organic pig and poultry farms in Western Europe. This paper summarizes the discussions. Rodent management is necessary to protect the food production chain from health hazards to livestock and humans. Some organic farmers prefer biological rodent control, but since rodents can also transmit diseases this bears certain risks for the production of healthy livestock and safe food. Effective rodent management requires a thorough understanding of the biology of the pest species concerned. These can be divided into two groups: field rodents, such as voles, and commensal rodents like house mice and rats. The objective of managing field rodents is to minimize livestock exposure to these vectors, and to regulate their populations in case their density is expected to grow dramatically. Infestation of livestock facilities with commensal rodents can be prevented, but once they are present, their eradication must be aimed for. General elements of rodent management are (1) the prevention of rodent infestations through strategic actions such as modifying the habitat or rodent proofing of the buildings, (2) monitoring their appearance and population density, and (3) rodent control measures. A number of possible management actions is described to provide a basis for examining the measures’ social acceptability, their economic and environmental impacts, and their efficacy

Effects of the compulsory indoor confinement of organic layer poultry: a dust storm!

In August 2005 an order was issued in the Netherlands for free range poultry to be kept indoors to prevent the introduction of avian influenza. The Animal Sciences Group of Wageningen UR (Wageningen University and Research Centre) conducted a telephone survey at the start of this indoor confinement regime to establish its effects on the wellbeing of laying hens and to chart the economic consequences for the poultry keepers. The survey revealed that, according to the poultry keepers, the impact on the wellbeing of the birds was not serious, thanks to the introduction of enrichment material such as extra litter and extra feeding. And the economic consequences were confined to an increase in the amount of work associated with the special enrichment measures. To obtain a more objective picture of the consequences of the indoor confinement order, the researchers visited 37 organic layer poultry farms during November and December. Despite the rules having been relaxed, these farms were still keeping their laying hens indoors. During each visit various parameters were scored, including: strain and age of hens, dimensions and equipment of the sheds, method of ventilation, general appearance of the hens, plumage, mortality and use of enrichment material. In addition, a quantitative measurement of dust was made in the sheds. Like the first study, this follow-up study also showed that compulsory indoor confinement had not led to any serious wellbeing problems. Admittedly, the condition of the laying hens' plumage often left something to be desired, but this depended to a very large extent on the strain of hens and their age. It was not possible to say to what extent the protracted indoor confinement of the hens was responsible for the mediocre condition of their plumage, since no control observations were made on farms where indoor confinement was not imposed. Serious feather pecking was observed occasionally, but did not lead to cannibalism. No correlation could be found between the outward appearance of the laying hens and the use of enrichment materials such as straw bales, etc. As this was an observational study, it is quite possible that the use of enrichment material was frequently prompted by the existing behaviour and general condition of the animals, as a result of which farms with few such problems had less need to take extra measures. Thus, it was not possible to determine the effect of the enrichment measures on the wellbeing of the animals in this way. In general, it emerged that poultry keepers often paid extra attention to their flocks at the start of the compulsory confinement period, providing extra litter or feed as enrichment, but gradually cut back on these extra measures. The study revealed that most farms were still using laying hens whose beaks had been tipped. It is not clear to what extent the absence of major feather pecking problems can be attributed to this. Further research is needed into the impact on feather pecking of the introduction (on 1 March 2006) of a prohibition on beak-tipping in organic poultry keeping, notably when animals are compulsorily confined indoors. Particularly striking were the high dust levels measured in the sheds (average 4.5 mg/m3). It was clear that the amount of dust in the sheds was directly related to the density of the laying hens and the strain of hen. The latter may be because a placid strain of hen is less prone to scratching and scraping and thus generates less dust. In particular, sheds with a "volière" (tiered aviary) system tended to have high dust concentrations (6.9 mg/m3). Previous researchers have reported that a dust concentration above 3.7 mg/m3 is bad for animal health. In summary, it can be stated that the harmful effects associated with indoor confinement can be mitigated by giving animals more enrichment. However, this present study is unable to pronounce on the effectiveness of the individual enrichment measures. It was clear that the dust levels in the sheds where laying hens are confined are too high and that this is related, inter alia, to the system employed in the sheds

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

Characteristics of Organic Pig Production and risk analysis concerning Toxoplasma infection

A short written questionnaire was used to study certain characteristics of the organic pig production chain in The Netherlands and the circumstances on the farm that might play a role in the transmission of Toxoplasma infection to the pigs. Of the 81 certified organic slaughter pig farmers present in the Netherlands in 2006, 52 responded to the questionnaire (64 % response). The farms could be divided into two populations. One population was represented by small organic pig farms with a mean number of 55 slaughtered pigs per year. These farms covered 40% of the total number of investigated farms, but only represented 2.5 % of the total number of slaughtered pigs. The second population had a mean annual production of 1460 animals. Almost 95% of these animals are currently slaughtered and further distributed by the Vion Food Group (de Groene Weg). A small part of the pigs (4%) is directly delivered to a slaughter company in Germany (Thönes) and 1% is sold via farm home sales. For each farm an arbitrary Toxoplasma risk factor analysis was performed. Factors included the type of outdoor run (concrete or soil), feeding goat or sheep whey, number of cats, access of cats to outdoor run, stables and feed, rodent control and covering roughage fed to the animals. Calculation of the total risk score (summation of chance times severity scores for several factors) showed that many farmers already used management factors that decreased the risk for Toxoplasma infection. Analysis of a possible relation between risk score and farm size showed that a poor score was often seen on small farms. Because these farms mainly sell their meat in a frozen condition via home sales, this is not considered to represent a problem for food safety. Further research is needed to investigate whether the risk for Toxoplasma can be maintained via on farm prevention or whether a Toxoplasma monitoring program should be implemented at slaughter, possibly with post slaughter decontamination. The fact that a recent report by the RIVM on food related infections has concluded that Toxoplasmosis has a markedly higher disease burden than Campylobacter or Salmonella, emphasizes the priority this subject should be given on the research agenda

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

Role of rodents in transmission of Salmonella and Campylobacter

Salmonella and Campylobacter are generally regarded as the most important food-borne pathogens in the world. Reduction or elimination of these pathogens in the first part of the food chain (on the farm) is important to prevent disease among consumers of animal products. In organic farming, elimination becomes more difficult, as food animals are allowed outdoors and have easy access to potential sources of hazardous pathogens. Whilst rodents are often associated by organic farmers with infrastructural damage and eating or spoiling of stored feed and products, their zoonotic risks are frequently underestimated. They can amplify the number of pathogens in the environment and transfer them to food animals. Thus organic farmers should be aware of the need for rodent control from a food safety perspective. Preferably, rodent control should form an integral part of a total package of hygiene measures to prevent transfer of food-borne pathogens. These should also include e.g. control of wild birds and flies and obligatory disinfection of boots/clothes and equipment for farm workers and visitors

Dioxins in organic eggs: a review

Eggs contribute for about 4% to the daily dioxin intake of humans. Research among layer farms in the Netherlands and other EU countries has shown that organic eggs contain more dioxin than conventional ones and that a significant number of organic farms produce eggs with a dioxin content that exceeds the EU standard. The hens’ intake of dioxins from various sources leads to an increase in the dioxin content of organic eggs. These sources include plants, feed, soil, worms and insects, and compared with hens on conventional and free-range farms, organic hens make more use of these sources due to better access to the outdoor run. Plants appear to be relatively unimportant as a source of dioxins. Also commercial organic feed generally has very low dioxin contents, but not much is known about non-commercial feed. Consumption of worms and insects and particularly ingestion of soil are important causes of high dioxin levels in eggs. Management interventions, like a reduction of the time the hens spend outside, may decrease the dioxin levels in organic eggs but at the same time may interfere with the image of the organic production system

Vliegenbestrijding in de biologische varkenshouderij: een enquête en evaluatie van een meetmethode = Fly control on organic pig farms: a survey and evaluation of a monitoring method

Organic farming is associated with biological solutions for pest control. Flies can be such a nuisance on organic pig farms that the farmers turn to chemical weapons for controlling the problem. This became apparent after an interview of 39 organic pig farmers. Half of the farmers used chemicals to control flies and only five mentioned the use of natural predators. Manure management on many farms was irregular and was not adequate for optimal fly control. Some farmers circulated the manure in an attempt to drown fly larvae and pupae. Monitoring methods to quantitate flies in the stables showed that the sticky traps was preferred over the spotcard method

Animal-friendly production systems may cause re-emergence of Toxoplasma gondii

Toxoplasmosis is still one of the most common parasitic infections in the world, although in Europe improvements in hygiene and the introduction of ‘total’ indoor farming in livestock production have rapidly diminished the problem during the past decades. As a result of public dislike, however, introduction of alternative and more acceptable animal-friendly livestock production systems including outdoor access are gaining ground. Potentially these systems can lead to increased prevalence of certain zoonotic diseases, including Toxoplasmosis. To retain prevalence of this disease in humans at current levels, emphasis should be on disease control at farm-level. This article provides an analysis of various risk factors for farm animals to get infected with Toxoplasma gondii. Access of cats to the farm premises, the use of compost and goat whey, and rodent control were identified as possible risk factors that should be addressed. Consumers should be aware of the fact that Toxoplasma infection, besides through meat, can also be caused by the uptake of contaminated water, soil, fruit and vegetables