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

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

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

Analysis of black holes in our knowledge concerning animal health in the organic food production chain

Although a large body of research on health aspects can be found via the web or in conference proceedings, only few papers reach the peer reviewed literature. This aspect makes it difficult to judge the quality of available data that relate to health aspects associated with organic livestock production. Many data deal with "on farm case type studies" which often do not lead to a direct relation between certain management procedures and incidence of certain health aspects. The principle that organic held animals are in better condition concerning their health as compared to conventionally held animals has not yet been proven. Well-controlled studies are needed to show the effects of organically held animals on innate and adaptive immune responses and disease susceptibility. The conditions in organic livestock production lead to novel challenges concerning social interactions, physical requirements, climatic conditions and infectious burden which requires certain breeds of animals that differ considerably from the conventionally held animals. More research is needed to identify these breeds whereby breeding selection criteria specific to organic conditions and principles should be used. A number of health problems such as infestation with parasites is an important problem that has been noted in organic livestock (poultry and pig) production and more research is needed to both prevent and treat these infections. Although largely recommended, phytotherapy and homeopathy do not have any demonstrated efficacy in managing helminths. A multidisciplinary approach is needed to address these questions. Investigations should be concerned with aspects such as rotation, stocking density, disinfections strategies, genetic predisposition and novel (plant derived or biological) antihelminthics. A major drawback in the use of phytotherapeuticals is the lack of good clinical trials, most claims are based on traditional use, anecdotal evidence or extrapolation of human data. Another problem is the consistency/standardisation of the product; variations exist in the levels of "active" ingredients between lots. Extensive studies have shown that garlic has a beneficial effect on human health and therefore would possibly be a suitable candidate to increase the health of animals in organic production. Further research is needed to substantiate this claim. Although mastitis is not seen more often in organic dairy production compared to conventional farms, it is still frequently encountered and both basic and applied research concerning prevention and cure without the traditional use of antibiotics is needed. More knowledge is needed concerning effects of alternative treatments in organic livestock production. As long as alternative treatments have not formally been proven to be effective, allopathic treatments should be preferred. Studies are needed concerning the welfare aspects of disease and insufficient or postponed treatment in organic animal production systems. It is generally accepted that feather picking and cannibalism is a major problem in organic poultry and more research is needed to counter this unwanted behaviour of the animals. The following aspects including genetic influences, housing environment, feed composition and the presence of external parasites may be involved. Vaccination has been one of the largest success factors in the prevention of disease in production animals. Most vaccines used nowadays are genetically engineered and should thus carry the GMO label. GMO based vaccines produced by incorporating genetic material from bacteria or viruses into plants is an attractive approach but does not comply with the principles of organic farming. Investigations concerning various vaccination strategies with or without GMO approaches should be evaluated to prevent various infectious diseases in organic livestock production systems. Organic livestock production leads to an increase or re-emergence of certain zoonotic diseases ( Campylobacter, toxoplasma). This is a serious drawback concerning claims that organic products are healthier as compared to conventional products and research into the prevalence of certain zoonotic infections, risk factors, farm management, post slaughter decontamination and consumer perception/education is badly needed. Several micro-organisms are described to be present in feeds and could be sources of infections of farm animals. Such pathogens can be either present on the outside of the plant (epiphytes) or on the inside of the plant (endophytes). The incidence of pathogenic bacteria in/on plants used for organic animal feed is not clear and therefore research on the incidence of these pathogens is needed. Biological cycles such as the utilisation of manure from organic farms may potentially lead to the creation of infectious reservoirs. Research is needed to provide evidence for this hypothesis and strategies should be devised to prevent this problem. Little is known about the role of pests in the occurrence of disease in organic livestock production. Research is needed into the efficacy of alternative pest control strategies since current pest control methods are not in agreement with organic production principles (use of anticoagulants for rodent control). The obligatory use of straw bedding in swine household management leads to higher dust and bioareosol (endotoxin) levels in stables. This may affect susceptibility to lung disease (farmer and animal) and investigations concerning measures to reduce dust and bioaerosol levels are needed. Current literature on this subject is not concordant and true differences may exist between management systems from different countries. Piglet mortality is an important problem in organic production systems and research concerning genetic and housing aspects is currently performed but not yet reported in the peer-reviewed literature. Amino acid imbalance and research into novel feed sources with high protein content is needed. More knowledge is known concerning possible anti-nutritive factors in these feeds and the effects of these new nutrients on gut health of the animals. Amino acid imbalance may lead to higher excretion of excess amino acids into the environment. On farm research should be performed to substantiate whether these claims also apply to organic production systems. It has been suggested that organic feeds for animals in organic production systems may contain higher mycotoxin levels thereby adversely affecting their health status. As yet no conclusive data concerning this issue has been published and research into this area is needed to prove or reject this myth. As yet it is not known whether phytase levels in organic feed for pigs are sufficient to allow optimal utilisation of organic phosphor thereby also leading to a lower environmental pollution; further investigations are needed in this area

Toxoplasma gondii Infection in Animal-Friendly Pig Production Systems

PURPOSE. Consumption of undercooked pork meat products has been considered a major risk factor for contracting toxoplasmosis in humans. Indoor farming and improved hygiene have drastically reduced Toxoplasma infections in pigs over the past decades. Whether introduction of animal-friendly production systems will lead to a reemergence of Toxoplasma infections in pigs is not yet known. Investigating this possibility was the purpose of this study. METHODS. Blood was obtained from pigs raised for slaughter and tested for Toxoplasma antibodies by using latex agglutination and indirect immunofluorescence testing, with confirmation by immunoblotting. RESULTS. None of the slaughter pigs (n = 621) from conventional farms (n = 30) were positive, whereas 38 (2.9%) of 1295 animals from animal-friendly systems tested positive (n = 33 farms; 13 [39%] farms positive). CONCLUSIONS. The following conclusions may be derived from this study: Conventionally (indoors) raised pigs are free from Toxoplasma infection, and (2) animal-friendly production systems may lead to a reemergence of Toxoplasma infections, although many of these farms remain Toxoplasma free. Slaughterhouse monitoring of pigs from animal-friendly production systems combined with on-farm prevention strategies should be applied to ensure safety for consumers of the meat products obtained from these animals

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%

IL-17A stimulates the production of inflammatory mediators via Erk1/2, p38 MAPK, PI3K/Akt, and NF-κB pathways in ARPE-19 cells

Purpose: To investigate the signaling pathways involved in interleukin (IL)-17A -mediated production of interleukin 8 (CXCL8), chemokine (C-C motif) ligand 2 (CCL2), and interleukin 6 (IL-6) by ARPE-19 cells, a spontaneously arisen cell line of retinal pigment epithelium (RPE).Methods: Flow cytometry analysis and western blot were used to detect the phosphorylation of extracellular signal-regulated kinases 1/2 (Erk1/2), p38 mitogen activated protein kinase (MAPK) and protein kinase B (PKB; Akt) in ARPE-19 cells stimulated with IL-17A. These cells were further pretreated with a series of kinase inhibitors and followed by incubation with IL-17A. CXCL8, CCL2, and IL-6 in the supernatant were quantified by enzyme-linked immunosorbent assay (ELISA).Results: Coculture of ARPE-19 cells with IL-17A resulted in significant increases in Erk1/2, p38 MAPK, and Akt phosphorylation. Inhibition of p38MAPK, phosphoinositide 3-kinase (PI3K)-Akt and nuclear factor-kappaB (NF-kappa B), with the inhibitors SB203580, LY294002 and pyrrolydine dithiocarbamate (PDTC) respectively, reduced IL-17 (100 ng/ml) mediated production of CXCL8, CCL2, and IL-6 in a concentration dependent manner. Inhibition of Erk1/2 with PD98059 decreased the expression of the tested three inflammatory mediators when using low doses of IL-17A (0-10 ng/ml) but not at higher concentrations.Conclusions: IL-17A-induced production of inflammatory mediators by ARPE-19 cells involves Erk1/2, p38MAPK, PI3K-Akt and NF-kappa B pathways