Progress 09/15/99 to 09/14/04
Outputs
The principal objective of this project was testing of non-chemical methods of controlling gastrointestinal nematodes (GIN) of goats, primarily the use of nematode-trapping fungi. A series of confinement feeding trials in which goats were fed Duddingtonia flagrans as a small component of the diet to control GIN larval development in fecal pellets were successfully completed as part of this project. In a dose titration study in which several levels of fungal spores were fed to parasitized goats, all levels significantly reduced larval development in fecal cultures, with the highest and most consistent effect with 500,000 spores/kg body weight (BW) per day. In a second experiment, 100,000 fungal spores/kg BW were fed to parasitized goats every day, every 2nd day, and every 3rd day. The most consistent results were found with daily feeding, and this was our recommendation for use of this technology. This creates some challenges under grazing conditions, particularly in
assuring that all animals eat an appropriate amount of the fungus daily. We completed 2 grazing trials in which the fungal spores were mixed with supplement in a feed trough, and although the fungus reduced larval development in feces collected from the grazing animals, there was no evidence of a direct effect on fecal egg counts (FEC) or blood packed cell volume (PCV). Overcoming the challenge of daily feeding of the spores is a constraint to more widespread use of this technology. A bolus containing D. flagrans is under development, but is not available as of yet. Evaluation of fungal boluses under grazing conditions will be the next research to be done whenever the bolus technology is available. Additional work completed as part of this project included surveying producers as to their use of anthelmintics and goat production practices, testing of anthelmintic resistance of goat GIN on farms throughout Georgia, a 3-year GIN epidemiology study completed at the FVSU Agricultural
Research Station, and validation of the FAMACHA system of anemia detection in for goats and sheep on farms throughout the southern USA. Producer surveys showed that frequent use of chemical anthelmintics is the primary method goat farmers in Georgia use to try to control GIN. Anthelmintic resistance was much more widespread than expected, with multiple drug resistance (resistance to drugs in more than one anthelmintic family) found on most of the farms tested. In the epidemiology study, GIN contamination of pasture consistently increased during the spring, summer, and early fall each year, with reduced GIN in late fall and winter. Negative effects on the animal were greatest during pasture transition times (changing from cool-season to warm-season species dominance), including late spring and the fall-early winter period. The FAMACHA system was successfully validated for determining animals in the herd or flock most in need of treatment, allowing reduced use of anthelmintics and
slower development of anthelmintic resistance.
Impacts
Our work on anthelmintic resistance and use of the FAMACHA system has greatly impacted producers throughout the Southeastern USA by changing the perception of anthelmintics as a cure-all for parasite problems in small ruminants. Farmers reduced the use of ineffective dewormers as a result of this project, and with greatly increased on-farm use of the FAMACHA technology as a result of successful producer workshops in GA, FL, LA, AR, and several other states, the overall frequency of anthelmintic use on individual farms has been reduced, which is slowing development of anthelmintic resistance in small ruminant nematodes and making small ruminant production systems in these regions more profitable. The nematode-trapping fungi work has increased producer awareness of and interest in use of alternative, non-chemical GIN control technologies, but field testing of the fungus in a bolus formulation is needed before this method can be recommended as part of an integrated GIN
control strategy. Work from this project has been published in several scientific manuscripts and presented at a number of national and international professional meetings. This has impacted the scientific community by increasing awareness of the scope of the anthelmintic resistance challenge in small ruminants and the need for alternative, non-chemical control technologies. Research in these areas at other institutions in the USA and overseas has increased as a result of this project.
Publications
- Terrill, T.H., R.M. Kaplan, M. Larsen, O.M. Samples, J.E. Miller, and S. Gelaye. 2001. Anthelmintic resistance on goat farms in Georgia-Efficacy of anthelmintics against gastrointestinal nematodes in two selected goat herds. Vet. Parasit. 97:261-268 Mortensen, L.L., L.H. Williamson, T.H. Terrill, R.A. Kircher, M. Larsen, and R.M. Kaplan. 2003. Evaluation of prevalence and clinical implications of anthelmintic resistance in gastrointestinal nematodes in goats. JAVMA 223: 495-500.
- Terrill, T.H., M. Larsen, O. Samples, S. Husted, J.E. Miller, R.M. Kaplan, and S. Gelaye. 2004. Capability of the nematode-trapping fungus Duddingtonia flagrans to reduce infective larvae of gastrointestinal nematodes in goat feces in the southeastern United States: dose titration and dose time interval studies. Vet. Parasit. 120:285-296.
- Kaplan, R.M., J.M. Burke, T.H. Terrill, J.E. Miller, W.R. Getz, S. Mobini, E. Valencia, M.J. Williams, L.H.Williamson, M. Larsen, and A.F. Vatta. 2004. Validation of the FAMACHAc eye color chart for detecting clinical anemia in sheep and goats on farms in the southern United States. Vet. Parasit. 123:105-120.
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Progress 01/01/03 to 12/31/03
Outputs
Data from two confinement studies and a grazing trial with Duddingtonia flagrans fed to goats to control gastrointestinal nematodes were presented at the World Association for the Advancement of Veterinary Parasitology (WAAVP) meeting held in New Orleans, LA from August 10-14, 2003. Data from the 3-year goat nematode epidemiology study and from 2 studies on use of copper oxide wire particles to reduce nematode infections in small ruminants were also presented at this meeting. A scientific presentation on stress responses of parasitized goats was made at the Association of Research Director's Thirteenth Biennial Research Symposium held in Atlanta, GA, from March 29-April 2, 2003. Additional on-farm testing of anthelmintic resistance in goat nematodes was completed from June through July of this year, and data from 3 years on anthelmintic resistance testing in goats was presented at 'Smart Drenching' workshops in Georgia, Florida, Louisiana, Arkansas, and Puerto Rico in
2003. Work on evaluation of the FAMACHA system for determination of level of anemia in goats and sheep was completed this year, with a manuscript from the work submitted to Veterinary Parasitology. Producer and Veterinarian FAMACHA training workshops were completed in Georgia, Florida, Louisiana, Arkansas, and Puerto Rico. An additional grazing trial to evaluate effects of feeding copper wire oxide in bolus form to goats to control parasitic nematodes was completed during October and November, 2003. During the period from October through December, trials to evaluate the anthelmintic effectiveness of feeding hay from a condensed tannin-containing forage (sericea lespedeza), and a complete pellet containing 5% of a seaweed extract, to goats were completed. The latter two experiments were completed in January, 2004.
Impacts
Our work on anthelmintic resistance and use of the FAMACHA system is continuing to impact producers throughout the Southeastern USA and Puerto Rico by changing their perception of anthelmintics as a cure-all for parasite problems in small ruminants. Farmers are reducing use of ineffective dewormers and reducing the overall frequency of anthelmintic use, which is slowing development of anthelmintic resistance in small ruminant nematodes and making small ruminant production systems in these regions more profitable. Our FAMACHA workshops have been very well-attended, with a large number of producers purchasing the FAMACHA cards for on-farm use. The company in South Africa that distributes the FAMACHA cards said that they sold more cards in the USA than in their home country last year because of our work. Results from this year continue to show the promise of non-chemical means of controlling parasitic nematodes in goats using copper wire particles fed in a bolus, and
condensed tannin-containing forage fed as hay. Our work on on-farm testing of anthelmintic resistance was published in the August 15, 2003 issue of the Journal of the Veterinary Medicine Association, and our manuscript on biological control of goat parasites using nematode-trapping fungi was accepted for publication by Veterinary Parasitology in September of last year.
Publications
- Mweemba, C., R. Eckhart, G. Kannan, R.A. Kircher, and T.H. Terrill. 2003. Effect of gastrointestinal nematode infection on stress responses in goats. p. 43. In Proceedings of the Thirteenth Biennial Research Symposium of the Association of Research Directors, 29 March - 2 April, 2002, Atlanta, Georgia.
- Larsen, M., T.H. Terrill, O. Samples, S. Husted, J.E. Miller, R.M. Kaplan, and S. Gelaye. 2003. Potential of the fungus Duddingtonia flagrans to control nematodes in goats in southeastern United States: A dose-titration and dose-timing study. p. 133. In Proceedings of the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology, 10-14 August, 2003, New Orleans, Louisiana.
- Mortensen, L.L., L.H. Williamson, T.H. Terrill, R.A. Kircher, M. Larsen, and R.M. Kaplan. 2003. Evaluation of prevalence and clinical implications of anthelmintic resistance in gastrointestinal nematodes in goats. JAVMA 223: 495-500.
- Terrill, T.H., J.E. Miller, R.M. Kaplan, M. Larsen, R.A. Kircher, O.M. Samples, and S. Gelaye. 2003. Epidemiology of goat gastrointestinal nematodes in Georgia. p. 188. In Proceedings of the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology, 10-14 August, 2003, New Orleans, Louisiana.
- Watkins, A.D., J.E. Miller, T.H. Terrill, M. Larsen, and R.M. Larsen. 2003. Effectiveness of copper-oxide wire particles on the control of Haemonchus contortus in sheep. p. 198. In Proceedings of the 19th International Conference of the World Association for the Advancement of Veterinary Parasitology, 10-14 August, 2003, New Orleans, Louisiana.
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Progress 01/01/02 to 12/31/02
Outputs
A trial to evaluate the effect of feeding Duddingtonia flagrans to grazing does and nursing kids was completed from April-June, 2002. Fecal cultures showed that the fungus was effectively reducing larval development in the fecal pellets deposited on the pasture, but the trial was not long enough to show an effect on fecal egg counts or blood packed cell volume (PCV). The trial had to be cut short due to lack of pasture after a very dry spring. Data from the fungus dose titration, dose time interval, and grazing studies was presented at two international scientific meetings. The third and final year of the goat nematode epidemiology study on pasture was completed and the data compiled. Information from two years of university and on-farm testing of anthelmintics resistance in goats was presented to the scientific community at two international meetings in July, and to producers and county agents at a 'Smart Drenching' workshop held at Fort Valley State University in
November, 2002. Evaluation of the FAMACHA system for determination of level of anemia in goats was initiated at the University Research Station and on-farm. For all the animals tested, blood samples were taken for determination of PCV, and each animal was scored for anemia using the FAMACHA eye chart. Preliminary data analysis showed a negative correlation between FAMACHA and PCV, indicating that the FAMACHA system has potential for use in the Southern USA. Two grazing trials were completed in 2002 to evaluate new, non-chemical parasite control technologies, including feeding of an antioxidant-rich brown seaweed product to goats to improve their immune function, and feeding of copper wire particles in a bolus to parasitized goats. Improving immune function had no impact on fecal egg counts or blood PCV, but the copper wire particles significantly reduced fecal egg counts.
Impacts
Our work on anthelmintic resistance is impacting producers in the Southeast by changing awareness of drug effectiveness, with goat farmers reducing their use of ineffective dewormers and also reducing the overall frequency of anthelmintic use, which saves money and slows the development of anthelmintic resistance. The successful testing of the FAMACHA system for identifying anemic animals was described at our Smart Drenching workshop and is also increasing producer awareness of the need for selective treatment to reduce the rate of development of anthelmintic resistance in goat nematodes. Results from this year continue to show the promise of non-chemical means of controlling parasitic nematodes in goats, particularly using nematode-trapping fungi and cooper wire particles fed in a bolus.
Publications
- Terrill, T.H., J.E. Miller, M. Larsen, and R.M. Kaplan. 2002. Biological control of gastrointestinal nematodes using nematode-trapping fungi: sheep and goat studies from the southeastern US. p. 28. In Proceedings of the 3rd International Conference on Novel Approaches to the Control of Helminth Parasites of Livestock, 1-5 July, 2002, Moredun Research Institute, EdinBrough, Scotland.
- Kaplan, R.M., L.L. Mortensen, L.H. Williamson, T.H. Terrill, M. Larsen, and R. Kircher. 2002. Prevalence of anthelmintic resistance in gastrointestinal nematodes of goats in the southern United States. p. 17. In Proceedings of the 3rd International Conference on Novel Approaches to the Control of Helminth Parasites of Livestock, 1-5 July, 2002, Moredun Research Institute, EdinBrough, Scotland.
- Terrill, T.H., R.M. Kaplan, M. Larsen, and J.E. Miller. 2002. Emerging issues in control of nematode parasites of goats: anthelmintic resistance and biological control using nematophagous fungi. p. 144. In Journal of Animal Science, Volume 80, Supplement 1.
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Progress 01/01/01 to 12/31/01
Outputs
Prevalence of anthelmintic resistance in goats in Georgia was tested on 18 farms throughout Georgia in 2001. Three visits were made to each farm to collect fecal samples for counting parasite eggs in the laboratory. Resistance to anthelmintics from the three major anthelmintic classes were completed by both fecal egg count reduction tests and larval development assays. Data from a previous anthelmintic resistance study completed at the Fort Valley State University and The University of Georgia was published in the Journal of Veterinary Parasitology. Data from farmer surveys on anthelmintic use in goats (collected in 2000) were compiled and inputted to a database for statistical analysis. The second full year of a 3-year study to investigate epidemiology of goat parasites on pasture was completed in 2001. Also, the first year of a 2-year grazing study with goats to test the effectiveness of spores of Duddingtonia flagrans in reducing transmission of nematode larvae
from goat feces to pasture was completed.
Impacts
This year's work demonstrates that anthelmintic resistance in goat intestinal parasites is a widespread problem in the southeastern US, which threatens the goat industry in this region. These results again underscore the necessity of developing alternatives to chemical control of gastrointestinal nematodes, of which biological control appears to be one of the most promising
Publications
- Terrill, Thomas H., Ray M. Kaplan, Michael Larsen, Oreta M. Samples, James E. Miller, and Seyoum Gelaye. 2001. Anthelmintic resistance on goat farms in Georgia - Efficacy of anthelmintics against gastrointestinal nematodes in two selected goat herds. Veterinary Parasitology 97:261-268.
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