Oesophagostomum dentatum and Trichuris suis infections in pigs born and raised on contaminated paddocks

SUMMARY Transmission of Oesophagostomum dentatum and Trichuris suis was studied in outdoor reared pigs. Six farrowing paddocks were naturally contaminated in May to mid June 2001 by experimentally infected seeder pigs. Early July, 1 sow farrowed on each paddock and starting week 3 post partum (p.p.) the offspring was slaughtered serially every 2 weeks for recovery of O. dentatum and T. suis. Faeces was collected regularly for parasite egg counts and acid-insoluble ash (AIA) content as an indicator for geophagy. Weaning took place week 7 p.p. by removing the sow. Paddock infection levels were estimated in mid June (O. dentatum) and late November (O. dentatum and T. suis) using helminth naïve tracer pigs. Soil and vegetation samples were collected regularly. Despite a high initial contamination by the seeder pigs, O. dentatum paddock infectivity was negligible to low throughout the raising of the experimental piglets, which had a slow accumulation of nodular worms ending with a mean of 422 worms/pig week 19 p.p. As only few eggs developed to infectivity overall T. suis transmission was minimal. The first T. suis were recovered week 11 p.p. and the highest mean burden of 21 worms/pig was recorded week 19 p.p. The experimental pigs had high faecal levels of AIA though it was decreased from 53 % in 3 weeks old piglets to 15 % in 19 weeks old pigs. The results are discussed in relation to the biological characteristics of the 2 parasites and their occurrence in organic pig production

Non-midical control of parasitic worms in pigs

Generally there is a higher prevalence of intestinal parasites in organic pigs compared to conventional indoor pigs. It may be possible to reduce infection levels by ensuring that new animals are parasite free, using a moderate stocking rate, co-grazing cows and sows, using noserings, altering feed composition and feeding the pigs predatious fungi. In addition, paddock rotation is recommended in order to remove the pigs from the infectious parasite stages (eggs and larvae). Resent results show that the free-living larvae of the nodular worm do not survive for long on pasture. Overall, the nodular worm is considered to be less of a problem than other parsites. Eggs from the large round worm and especially the whipworm can take long to become infective but may in return survive several years in the soil. It seems as if ploughing may reduce the transmission of whipworm considerably, whereas the effect on the large round worm is not as strong. The large differences between the three parasites mean that control strategies may have to be designed according to the parasites present in a given herd

Ascaris suum infections in pigs born and raised on contaminated paddocks

The transmission of Ascaris suum was studied in outdoor reared pigs. From May to June, 2001 6 farrowing paddocks were naturally contaminated with A. suum using experimentally infected seeder pigs. Early July, 1 sow farrowed on each paddock. One piglet per litter was slaughtered every second week starting week 3 post partum (p.p.) for registration of liver white spots and recovery of A. suum from the lungs and the small intestine. The last pigs were slaughtered week 19 p.p. Faeces was examined for eggs and blood was analysed for A. suum specific antibodies. Weaning took place week 7 p.p. by removing the sow. Paddock infection levels were estimated by regular examination of soil samples and in late June and late November using parasite naïve tracer pigs. Paddock contamination was high but eggs developed slowly resulting in a low initial transmission to the experimental pigs. By week 5 p.p. transmission had increased and the numbers of infective eggs in the soil increased during the study. The results indicate a continuous uptake of infective eggs, but visceral larval migration was reduced with time probably due to the development of a pre-hepatic barrier. Nevertheless, a rather large population of adult worms remained in the pigs throughout the study, and it may primarily have been eggs ingested in the early infection phase that gave rise to the patent infections. It is suggested that neonatal exposure may result in increased persistence and size of adult worm burden and that the higher ‘life time worm burden’ may be of significant economic importance

Long-term survival of Ascaris suum and Trichuris suis eggs in relation to pasture management

Background: Organic pig production systems are commonly characterized by high helminth prevalences. This problem is partly associated with access to outdoor facilities such as pastures and more knowledge is needed on long-term pasture infectivity patterns to improve farmer advisory services and guidelines on pasture management. Methods: Six identical paddocks were originally contaminated in the spring to autumn of 2001 by pigs infected with high levels of Ascaris suum and low levels of Trichuris suis. Since then, no further eggs have been deposited and 3 of the paddocks have been ploughed to a depth of 20 to 28 cm and re-sown once a year while 3 paddocks remained untouched apart from yearly cutting of the vegetation. In the late spring and late autumn of 2001, 2002, 2003, and 2004 as well as in the autumn of 2005, 2007, and 2010, survival of parasite eggs was measured by analysis of soil samples and by recovery of worms from short-term exposed helminth naïve tracer pigs. Results: Following a high initial egg mortality in 2001-2002, the number of parasite eggs in the soil declined slowly over time for both species. In 2001, very few T. suis eggs developed to infectivity. The tracer data show that overall pasture infectivity for T. suis did not peak until 3-4 years after the initial contamination. Preliminary data from 2010 indicate that T. suis is still present on the paddocks, though at very low levels. Infective A. suum eggs were detected in 2001 and paddock infectivity levels peaked within 2 years after contamination, resulting in livers with very high numbers of white spots, irrespective of paddock treatment. Transmission of T. suis was more consistently reduced by ploughing compared to A. suum. Conclusion: Development and maturation of A. suum eggs and especially T. suis eggs was overall slower than expected, indicating that pasture rotation schemes should ideally exceed 3 years. However, 9 years after initial contamination, both species were still detected and A. suum pasture infectivity was still too high for the paddocks to be suitable for pigs. Overall, transferring the eggs deeper into the soil by ploughing appeared to reduce parasite transmission

Survival and development of Ascaris suum and Trichuris suis eggs in deep-litter on an organic pig farm

Background: Helminths are common in European organic pig production systems and the use of deep-litter has long been considered a serious risk factor contributing to this problem. However, until now hardly any data has existed to either support or reject this hypothesis, thus complicating formulation of farmer guidelines. Methods: On an organic Danish pig farm, 3 different areas (latrine, resting area and the area in-between) of 2 indoor fattening pens with deep-litter (min. 2 months old) were examined for Ascaris suum and Trichuris suis eggs. The deep-litter was sampled vertically 10, 20, 30, 40, 50, and 60 cm from the surface, by pooling 4 sub-samples per level. In addition, eggs were isolated from the top, middle, and bottom of deep-litter (3-4 months old) of the same areas but in 3 other pens. Percentage embryonation was determined before and after incubation in H2SO4 at 25OC for 7 weeks. For comparison, control eggs isolated from fresh faeces were also incubated. Results: Though less common in the resting areas, eggs of A. suum (0-481 eggs/g dry litter) and T. suis (0-58 eggs/g dry litter) were detected in all pen areas and vertically throughout the deep-litter, but the large majority of eggs was unembryonated and some were damaged. Hardly any eggs were partially or fully embryonated. Once isolated and given optimal conditions, eggs of both species from all 3 areas were able to develop to a larvated stage, but the ability to do so declined with the depth within the deep-litter. Compared to control eggs from faeces, A. suum eggs from deep-litter were less successful in embryonation while T. suis eggs from deep-litter had the same percentage embryonation as fresh eggs. Conclusion: For the first time data has shown that deep-litter may not be a risk factor for A. suum and T. suis transmission within the pens as previously suspected. However, it does appear that a high number of eggs may survive and potentially embryonate if they are transferred to a more beneficial environment. The consequence being that manure should not be spread indiscriminately onto pastures, which may later be used for pigs. A solution may be to inactivate the eggs first

Parasite impact, transmissions and control

Scientific Workshop on Organic Pig Production, Hovborg Kro, Holmeåvej 2, 6682 Hovborg, DK June 12th and 13th 2013 Welcome (Marianne Bonde, UHF) Sandra Edwards (UK): Future challenges in organic pig production Theme 1: Production of entire male pigs / Chaired by Jan Tind Sørensen The aim of organic pig production is to ensure high animal welfare and natural products. Banning castration is thus a logical step forward, but the risk of boar taint in the meat is a major barrier for marketing meat from entire male pigs. Is it possible to use genetic tools and breeding strategies to prevent boar taint? What is the effect of feeding, management, housing and hygiene? Is it possible to process the meat to minimize the risk of boar taint? These issues will be discussed based on the results from the research project NOCAST, as well as other on-going Danish research projects on entire male pigs. Susanne Støier (DK): Boar taint – detection, consumer response and product quality Hanne Maribo (DK), Bent Borg (DK) and Rikke Thomsen (DK): Reduction of boar taint – the practical way. Anders Strathe (DK): Prevention of boar taint by means of genetics and breeding Theme 2: Outdoor production of growing-finishing pigs, provision of roughage / Chaired by Jan Tind Sørensen Use of roughage and outdoor production are two very important characteristics in organic livestock production. How does the use of roughage affect health and performance in growing-finishing pigs? Is it possible to encourage outdoor pigs to find a large part of their food directly in the field where they are kept, and how does this influence pig performance and meat quality? These issues will be discussed on the basis of results from two major research projects, SUMMER and ICOPP. Liisa Voutila (FI): Effect of roughage on pig health and performance Anne Grete Kongsted (DK) and Margrethe Therkildsen (DK): Outdoor growing-finishing pigs: effect of genotype and feeding strategy on animal behaviour, performance and meat quality Theme 3: Environmental impact and animal welfare / Chaired by Jan Tind Sørensen Robust and competitive organic pig production must minimise environmental impact as well as ensuring good animal health and welfare. In theory, improving animal health and welfare reduces environmental impacts through decreased medicine use, improved growth rates and feed conversion efficiency. Is it possible to verify these hypotheses on working farms? The relationship between animal health, welfare and environmental impact will be discussed based on the results from the Core organic II research project ProPig including data collection on these aspects on 75 organic pig farms across Europe. More specifically, it will also be discussed how management practices may affect parasite transmission and thus animal welfare within organic systems (PAROL and NOCAST projects). Christine Leeb (A): Assessment of animal welfare and environmental impact. Helena Mejer (DK): Parasite impact, transmission and control John Hermansen (DK): Introduction to group discussions Group discussions Plenum discussion, chaired by John Hermansen Closing remarks / Marianne Bonde, UHF Dinner, social get-together Farm visit (Bus transportation from Hovborg Kro provided

Spolorm i økologiske svinebesætninger

Spolormen er en parasit, der lever i tarmkanalen og er udbredt i alle egne af verden, hvor der holdes grise. Spolormen kan være et problem, fordi den kan påvirke grisens tilvækst, foderforbrug og sundhed. Et igangværende treårigt Organic RDD projekt (PAROL) arbejder derfor på at kortlægge smitten i fem danske besætninger, for at forbedre rådgivningen omkring kontrollen af spolorm

Alternativ kontrol af indvoldsorm hos svin

De fleste almindelige indvoldsorm i danske svin er helt afhængige af værtsdyrenes nærmiljø, fordi en del af deres livscyklus skal gennemføres uden for værtsdyret. Ormene udskiller æg, som deponeres med værtens gødning i dennes omgivelser, hvor æggene dernæst udvikler sig til mere eller mindre hårdføre infektive stadier, som enten kan gensmitte værten eller smitte nye værtsdyr. Danske svin er gennem mange år blevet koncentreret i stadig større og mere intensive besætninger. Sammen med en udbredt brug af medicinering har dette forårsaget en markant reduktion i forekomsten og intensiteten af parasitter. Den økologiske driftsform, hvor forebyggende medicinsk behandling ikke er tilladt, og hvor dyrene skal have rigelig strøelse og adgang til udendørs faciliteter, er imidlertid en tilbagevenden til mere parasitfavorable betingelser. En undersøgelse i 1990-91 af 12 danske økologiske svinebesætninger påviste således en moderat til meget høj ormebelastning sammenlignet med konventi-onelle besætninger (Roepstorff et al., 1992), mens en nyere undersøgelse af 9 økologiske besætninger i 1999 (Carstensen et al., 2002) viste, at flere besætninger her havde et mere moderat infektionsniveau. Denne forskel mellem de to undersøgelser kan muligvis skyldes bedre faciliteter og øget viden og der-med en bedre håndtering af parasitproblemet i 1999. Det skal dog bemærkes, at besætningerne i begge undersøgelser generelt var forholdsvis nyetablerede. Vi har derfor kun ringe kendskab til eventuelle langsigtede problemer, da infektionerne muligvis ikke havde nået at blive opformeret på de benyttede arealer. I begge undersøgelser blev der kun påvist få arter af indvoldsorm, nemlig spolorm (Ascaris suum, 15-30 cm lang), knudeorm (Oesophagostomum spp., ca. 1 cm), piskeorm (Trichuris suis, ca. 5 cm) og tråd-orm (Strongyloides ransomi, ca. 0,5 -1 cm) - den sidstnævnte blev kun fundet sporadisk i den første under-søgelse. Normalt resulterer infektionerne i nedsat foderudnyttelse og tilvækst, men i værste tilfælde kan for eksempel piskeorm give utrivelighed og dødsfald. For konventionelle svineproducenter er kontrol med orm hos svin sædvanligvis synonym med orme-behandling, men dette er i strid med lovningen og de økologiske idealer, og der findes adskillige andre muligheder for at holde parasitinfektioner nede på et acceptabelt niveau i økologiske besætninger. Disse er kort præsenteret og kommenteret i tabel 1. Desværre er disse kontrolforanstaltninger kun undersøgt i relativt begrænset omfang, og det er derfor umuligt at drage klare konklusioner vedrørende de enkelte kontrolforanstaltningers potentiale, endsige give en anbefaling af et godt kontrolprogram, som kombinerer disse muligheder

Ikke-medicinsk kontrol af indvoldsorm i grise

Der er generelt en højere forekomst af indvoldsorm i økologiske grise i forhold til indendørs grise. For at reducere forekomsten af indvoldsorm kan man bl. a. sørge for at nye dyr er parasitfri, holde en moderat belægningsgrad, samgræsse søer med kvier, bruge næsering, ændre foderets sammensætning og fodre grisene med rovsvamp. Derudover anbefales det at man benytter foldskifte, så man fjerner grisene fra smittekilden (ormenes fritlevende larver og æg). Et større markforsøg har vist at larver af knudeormen overlever dårligt i det fri og må overordnet anses for at være et mindre problem. Æg af spolormen og piskeormen kan derimod overleve i flere år selvom især pisleormens æg kan være lang tid om at blive infektive for grise. Grises optag af æg af piskeormen ser ud til at kunne reduceres ved at pløje markerne, mens effekten ser ud til at være mindre for spolormen. De meget store forskelle imellem de tre ovennævnte indvoldsorm gør, at kontrolstrategier bør tilpasses afhængig af hvilke orm, der findes i en given besætning

Helminth parasites in pigs: New challenges in pig production and current research highlights

Helminths in pigs have generally received little attention from veterinary parasitologists, despite Ascaris suum, Trichuris suis, and Oesophagostomum sp. being common worldwide. The present paper presents challenges and current research highlights connected with these parasites. In Danish swine herds, new indoor production systems may favour helminth transmission and growing knowledge on pasture survival and infectivity of A. suum and T. suis eggs indicates that they may constitute a serious threat to outdoor pig production. Furthermore, it is now evident that A. suum is zoonotic and the same may be true for T. suis. With these ‘new’ challenges and the economic impact of the infections, further research is warranted. Better understanding of host–parasite relationships and A. suum and T. suis egg ecology may also improve the understanding and control of human A. lumbricoides and T. trichiura infections. The population dynamics of the three parasites are well documented and may be used to study phenomena, such as predisposition and worm aggregation. Furthermore, better methods to recover larvae have provided tools for quantifying parasite transmission. Thus, an on-going study using helminth naïve tracer pigs has surprisingly demonstrated that soil infectivity with A. suum and T. suis increases during the first 2–3 years after pasture contamination. Though all three helminth species stimulate the Th2 arm of the immune system, Oesophagostomum seems weakly immunogenic, perhaps via specific modulation of the host immune system. A. suum and T. suis potently modulate the host immune response, up-regulating Th2 and down-regulating Th1. As a consequence, A. suum may compromise the efficacy of certain bacterial vaccines, whereas T. suis, which establish only short-term in humans, is a favourite candidate for down-regulating autoimmune Th1-related diseases in man. Some basic research findings have offered new possibilities for future sustainable control measures. For example, the heredity of host resistance to A. suum and T. suis is so high that breeding for resistant pigs may be a possibility. Experimental studies have demonstrated that fermentable dietary carbohydrates have an antagonistic effect on Oesophagostomum and to a lesser extent on T. suis and A. suum, whereas egg-destroying microfungi may be used to inactivate the hard-shelled A. suum and T. suis eggs in the environment. Helminth control in Denmark has previously relied solely on anthelmintic treatment in herds with low helminth transmission. When indoor transmission rates increase, or in outdoor herds with high pasture contamination levels, medication may advantageously be combined with sustainable control measures, such as selected pig genomes, bioactive forages, and egg-destroying microfungi. © 2011 Elsevier B.V. All rights reserved