Novel Methods for Sustainable Control of Gastrointestional Nematodes in Small Ruminants

Novel Methods for Sustainable Control of Gastrointestional Nematodes in Small Ruminants

Summary

Controlling gastrointestinal nematodes of goats and sheep requires an integrated program with targeted use of chemical anthelmintics (“smart drenching”), and novel, non-chemical control technologies. To target animals needing treatment, the FAMACHA system was validated for sheep and goats at sites throughout the southern USA and US Virgin Islands. Smart drenching and FAMACHA workshops were given in GA, FL, LA, AR, and Puerto Rico. Trials testing nematode-trapping fungi, copper oxide particles, and tannin-containing forage hay to control parasites in sheep and goats were completed. A manuscript from FAMACHA validation work, an extension publication on smart drenching, and the project web site were finalized.

Objectives/Performance Targets

1. Bring about immediate improvement in GIN control and subsequent productivity in small ruminant operations in the southern U.S. and the US Virgin Islands by disseminating to producers and extension agents current knowledge and technology.

2. Investigate and implement the use of novel non-chemical approaches in integrated, sustainable control strategies of GIN in small ruminants.

3. Determine the economic impact on the small ruminant industry of uncontrolled multi-drug resistant GIN.

Accomplishments/Milestones

Materials and Methods

Program-of-work development

Team members assembled for three project update/planning meetings in 2003. The first and third meetings were held on May 28-29 and December 18-19, 2003, respectively, at the Fort Valley State University Agricultural Research Station. The second meeting was held in New Orleans on August 15th, following the World Association for the Advancement of Veterinary Parasitology (WAAVP) meeting held from 10-14 August. At these meetings, updates on project progress were given by each of the area research coordinators, and updates on progress on project web site development and preparation of scientific and extension-type publications associated with the project were given. Successes and challenges encountered in project activities since our previous meeting were discussed each time, with adjustments made in our planned activities as needed to continue progressing toward meeting project objectives.

Objective 1

Smart Drenching and FAMACHA Workshops

Arkansas.
J. Burke hosted the 2003 Sheep and Goat Field Day at the Booneville USDA Station on September 20, 2003. Dr. James Miller presented Safe Drenching Techniques and FAMACHA demonstration. The field day was attended by nearly 200 sheep and goat producers. Smart drenching presentations were also made by J. Burke to goat producers in Yellville, AR (60 dairy goat producers), Ferndale, AR (40 goat producers) and Marshall, AR (90 meat goat producers) in March and April, 2003.

Florida.
FAMACHA workshop presented by R. Kaplan and hosted by M. Williams in Gainesville, FL, at the Goat Production Conference, June 14-15 (60 small farm and minority producers in attendance).

Georgia.
Workshop entitled “FAMACHA Wet Lab” was presented to veterinary students by R. Kaplan at the Student AVMA, National SAVMA Symposium held in Athens, GA, March 20-22, 2003.

Louisiana
Update on small ruminant nematode parasite control. LSU SVM Annual Conference of Continuing Education. September 14, 2003. Baton Rouge, LA. (Presentation only, 25 in attendance), presented by J. Miller.

Puerto Rico
In November, 2003, a Smart Drenching Workshop was held at the University of Puerto Rico in Mayaguez, PR, with 35 attendees. At the workshop, farmers viewed samples of the producer survey work sheets for goats and sheep and requested that they be translated into Spanish. Work on the Spanish translation of the survey was started in December, 2003.

In addition to the separate workshops, appropriately screened projects results and observations were incorporated into formal general Extension program meetings reaching 98 goat or sheep owners in 7 counties and clusters in Georgia during 2003. These meetings were organized in collaboration with local county agents or young farmer advisors and made the audience generally aware of new and different approaches to internal parasite management. The information was supported through power point presentations and other visual aids. Time was taken to explain the general theory that justified the new approach. Questions were answered to clarify the concept and provide additional information.

Other outreach activities

A project website and glossy color publications on the concept of smart drenching and use of the FAMACHA chart in the USA will serve as tools for sharing information about the project objectives and a sensible approach to management for sustainable GIN management. The web site development is being coordinated by FVSU scientists and non-university computer services personnel. The University of Georgia has taken the lead in developing the informational brochures that will be produced at FVSU. The website will be updated from time to time with new information on upcoming workshops and will provide copies of survey forms and the like for the convenience of participating clients who have access to the Web.

Tests for anthelmintic resistance

The DrenchRite© larval development assay work to determine prevalence of anthelmintic resistance in sheep and goat gastrointestinal nematodes from each region participating in the project was continued in 2003, with 4 additional farms tested, bringing the total number of farms tested to 27 with 25 of these providing good, useable data. All samples were analyzed at the University of Georgia, College of Veterinary Medicine parasitology laboratory, but the data analysis is not yet complete. The assay failed to yield useable results for 2 farms. Testing was interrupted due to an extended unavailability of the DrenchRite Assay Plates. Since large scale retesting could not be performed again until Spring, 2004, which would have been 2 full years after the initial farms were tested, we decided to stop and begin analysis and interpretation of the data already completed. These data will be used to select efficacious anthelmintics for deworming animals at each research site.

An on-farm test of moxidectin resistance in GIN of goats was completed in Georgia during June-July, 2003. Resistance was determined on 10 different farms using both the DrenchRite© larval development assay technique and fecal egg count reduction (FECR) tests. Most of the data have been analyzed, and a manuscript from this work will be submitted in 2004.

Sheep and goat producer surveys

Revisions were completed on the sheep and goat producer surveys to be used to gather current farmer-based animal and internal parasite management information from throughout the southern USA and Puerto Rico. A single survey form for both sheep and goat producers was developed and will be sent out to lists of producers in 2004. The survey will also be posted on our project web site to allow producers to complete it and send the information in on-line. The sheep and goat survey instrument was validated at the 2003 Goat-A-Rama held near Tennille, GA in Washington County in April, where over 30 goat owners completed the draft questionnaire. Surveys were also filled out by 15 goat and sheep producers attending the Sunbelt Agricultural Exposition held in Moultrie, GA, during October, 2003.

Objective 2

This section provides information on materials, methods and activities associated with our effort to investigate and implement the use of novel non-chemical approaches in integrated, sustainable control strategies of GIN in small ruminants.

FAMACHA validation

Validation of the “FAMACHA system” as a means of minimizing use of anthelmintics was completed in 2003, with a scientific manuscript prepared and submitted to the journal Veterinary Parasitology. Weaned and mature sheep (n = 847) and goats (n = 537) of various breeds and ages from Arkansas, Florida, Georgia, Louisiana, and the US Virgin Islands were included in the analysis. For all of the animals, the color of their ocular mucus membranes were evaluated using the FAMACHA card, which is a laminated chart showing pictures of the eyes of sheep at five levels of parasite-induced anemia, from 1 (red, healthy animal) to 5 (white, severely parasitized animal). Blood and fecal samples were also taken from each animal for PCV and FEC analysis, respectively. The relationships between FAMACHA score, PCV, and FEC were determined separately for sheep and goats using Spearman correlation coefficients.

New guidelines for the use of the FAMACHA system in the USA and the Caribbean, based upon the validation results, were developed in 2003 and will be published and distributed with the FAMACHA cards during the duration of the project.

Nematode-trapping fungi

Testing of potential of Duddingtonia flagrans as a biological control agent against parasitic nematodes continued in year 2 of the project in a grazing trial with pregnant and nursing ewes in an experiment at LSU, and in a confinement feeding trial with lambs at the USDA Research Station in Booneville, AR. In the second study, possible interactions between D. flagrans and copper oxide wire particles (COWP) given in a bolus form were studied. In this experiment, 55 lambs were supplemented with the fungus (n = 28) or control supplement (n = 27), with half of each supplement group given a bolus containing COWP. Feces and blood were collected weekly to determine fecal egg counts (FEC) and blood packed cell volume (PCV). The feces were cultured to determine viability of the D. flagrans. Data from this study are currently being analyzed.

Copper-oxide wire particles

Use of COWP in the diet of ruminants has potential to assist in controlling parasitic nematodes, and several trials were completed in 2003 to test this technology with sheep and goats.

A trial to determine the optimal dose of COWP for sheep was completed at the USDA Station in AR from June-July, 2003. Lambs were given a 1-time challenge of 10,000 H. contortus larvae and maintained in confinement on a corn/soybean diet with access to bermudagrass hay. After infection levels increased, the lambs were given 0, 2, 4, or 6 g of COWP in a single bolus. Feces and blood for FEC and PCV analysis were collected weekly for 28 days, after which the animals were slaughtered to recover and count adult worms in the gastrointestinal tract, and to measure copper levels in the liver.

During the spring and summer grazing period of 2003, the effect of COWP was evaluated for controlling nematode parasite infections in sheep at LSU. Thirty grazing and nematode parasite infected ewes were randomly assigned to treatment and control groups of 15 each. The treatment group was administered a bolus containing 4 g of COWP and 15 ewes remained untreated as controls. Similarly, 24 weaner lambs were allocated and given boluses containing 2 g of COWP. Infection level was monitored throughout the period by weekly fecal and blood collection for FEC/culture and PCV, respectively. Serum Cu levels were determined before Cu administration and at the end of the study.

At FVSU a grazing trial was initiated in October, 2003, to test the effectiveness of COWP against mature Spanish does given a 1-time drench of 10,000 infective H. contortus larvae. Twenty does were ranked by FEC and randomly assigned to 1 of 2 treatments: Treatment 1 included pasture grazing plus a single dose of COWP (4 g per dose) placed down the throat in a gelatin capsule 4 weeks after the parasite challenge was given. Treatment 2 included pasture grazing plus a capsule with no COWP. The trial was completed on January 10, 2004. Feces were sampled weekly for fecal egg count determinations, and data from this experiment is currently being analyzed. Additional trials with COWP fed to goats will be repeated during summer, 2004.

Tasco seaweed extract

Tasco seaweed extract contains several antioxidants that have been shown to improve immune function in livestock, including goats. Improved immune response has been reported to allow higher tolerance to parasitic infection. To test the effect of supplementing parasitized goats with feed containing the Tasco seaweed extract, a confinement feeding trial was completed at FVSU from October, 2003 to January, 2004. Thirty-two Spanish does were given a 1-time drench with 10,000 H. contortus larvae, and 4 weeks after the parasite challenge, the 32 animals were ranked according to their FEC level and randomly assigned to 1 of 2 treatments, pelleted Tasco feed with seaweed extract included at 5 % of the ration, or Tasco feed without seaweed extract added. For both treatments, Tasco feed represented approximately 40 % of daily intake, with ground bermudagrass hay making up the remaining 60 %.

Blood samples for determination of total immunoglobulin, differential cell counts, and PCV and fecal samples for determination of EPG were taken from all does on a weekly basis. At the end of the feeding period, all the does were subjected to 6 hours transportation, with blood samples taken from all animals hourly during the transport period to determine levels of stress hormones under simulated pre-slaughter conditions. Blood parameters from this trial are currently being analyzed.

Condensed tannin forage

Forages containing condensed tannins (CT) have been reported to have anthelmintic properties when fed to or grazed by ruminants. This possibility was explored in experiments with sericea lespedeza, a high-CT, warm-season perennial legume, at FVSU and the USDA Station in Booneville, AR. In the FVSU study, a confinement feeding trial with 20 mature Spanish does was initiated in October of 2003 and completed in January of 2004. The does were given a 1-time drench with 10,000 H. contortus larvae and allowed to graze for 4 weeks, after which they were ranked according to FEC level and randomly assigned to 1 of 2 treatments; energy and protein-balanced complete rations consisting of chopped hay (approximately 80% of daily intake) and a small amount of concentrates. For treatment 1, the hay portion of the diet was from sericea lespedeza, while the treatment 2 hay was bermudagrass, which contained no condensed tannins. The two rations were fed to the does in pens for 5 weeks, after which all the does were fed the bermudagrass diet for an additional 3 weeks. Fecal samples to determine FEC were taken weekly throughout the trial. Data from this trial has been analyzed and a manuscript prepared and submitted to the South African Journal of Animal Science.

Preliminary work with sericea lespedeza and alternate forages fed to lambs for control of H. contortus was completed at the USDA Research Station in Booneville, AR in 2003. Weaned lambs were inoculated with 500 H. contortus larvae 3 times over a period of 1 week. Twenty lambs were given diets of sericea lespedeza or tall fescue hay plus concentrates. Percentage of lespedeza in the hay was between 50 and 90%. Blood and fecal samples to determine PCV and FEC were taken weekly from individual animals during the 12-week trial.

Objective 3

Estimating the economic impact of management changes is an important part of the decision-making process. Therefore a major part of this project is to determine the economic impact of controlled and uncontrolled multi-drug resistant GIN to the small ruminant sector.

The economic analysis completed at this stage in the project has focused on reduction of drug use by treating animals based upon FAMACHA scores rather than by a particular deworming schedule. Preliminary work in repeated use of FAMACHA to identify goats or sheep in need of treatment during the Haemonchus season (May-October) was completed in year 2 at LSU, FVSU, and the USDA Station in Booneville, AR. At each institution, animals were scored with FAMACHA, only animals with a FAMACHA score of 4 or 5 were dewormed, using an effective dewormer (As determined by the larval development assay technique). Number of animals dewormed throughout the season was compiled and compared with a total herd deworming schedule based upon the calendar, which is a typical deworming regiment. Data from FVSU and Booneville are still being compiled, but LSU data has been compiled. As data are accumulated and analyzed, the results will be channeled to the coordinator of the economics element and used to establish projections and timelines that can be understood by our clients and technical specialists.

Education and Outreach

Extensive opportunities were developed for education and outreach in 2003, mainly through our smart drenching and FAMACHA workshops. Opportunities are being taken at these workshops and other venues to explain the process of validation of the FAMACHA system and the principles involved in using the tool.

The project webpage is not yet complete but it will be used for education and outreach as well as for background information on the project. Information on the project was included in the Winter/Spring and Summer/Fall editions of the Georgia Small Ruminant Research and Extension Center (GSRREC) newsletter in 2003. Additional issues of the newsletter will be forthcoming in Year 3.

Information on the work was described in University newsletters for both FVSU and UGA in 2003, and news releases were prepared at each institution.

Additional information on the project was provided by scientists and extension specialists in each participating region. For example, individual requests for related information came to the Extension specialists associated with the project at Fort Valley State University. Thirty-two (32) replies were provided via e-mail, phone, or letter from the production specialist alone. More detailed information was provided by the Extension Veterinarian.

Results and Discussion

Workshops

Hundreds of sheep and goat producers have attended our smart drenching and FAMACHA workshops, receiving hands-on training in use of the FAMACHA system for targeting parasitized animals in their herd or flock. Over 300 FAMACHA cards were distributed to trained individuals during 2003.

These meetings resulted in an awareness among members of the audience that there are alternative approaches to internal parasite management that lead to a more sustainable meat goat or sheep enterprise.

Anthelmintic resistance tests

Results of the DrenchRite© assays that have been completed to date continue to show widespread prevalence of anthelmintic resistance in sheep and goat nematodes throughout the southern USA and Caribbean. There was resistance to Albendazole and Ivermectinon on nearly 100% of the farms tested, with some instances of resistance to Levamisole. In the moxidectin resistance study carried out in Georgia, 50% of the farms tested had resistant nematodes. In a study completed on the same farms only two years earlier, Moxidectin was nearly 100% effective.

FAMACHA eye chart validation

The FAMACHA system for determination of parasite-induced anemia was successfully validated for both sheep and goats in the southern USA and the Caribbean Islands. This tool will allow producers to identify and treat those animals in their herd or flock most in need of treatment, which will save on anthelmintic costs, reduce the rate of development of anthelmintic resistance, and help in identifying animals that are most prone to parasite infection and should be culled. All of this will improve the economic viability of small ruminant production systems in these regions.

Smart Drenching Pamphlet, FAMACHA Guidelines

A revised draft of the ‘Smart drenching’ pamphlet was developed by L. Williamson, and distributed to all project participants for peer review in December, 2003, and final copy ready for printing should be available by Spring 2004. A revised draft of the FAMACHA Guidelines for use of the tool in the USA and Caribbean was also distributed to project participants at our December meeting at FVSU, and printing of the new Guidelines will also begin in Spring, 2004.

Nematode-trapping fungi

Work in 2003 confirmed earlier studies with D. flagrans in grazing trials, which was that the fungus was viable and reduced larvae on pasture, but so far has not been shown to have a large impact on production parameters in small ruminants

Copper oxide wire particles experiments.

Grazing trials at LSU.
Results from this work indicated that COWP significantly reduced the level of Haemonchus contortus infection in both ewes and lambs. Serum Cu levels were below normal levels both before and at the end of the study. Grazing sheep in this region appear to be Cu deficient and may not have problems with Cu toxicity.

Confinement study at USDA Station, Booneville, AR
All dose levels of COWP significantly reduced FEC in the lambs, from more than 8000 eggs/g feces to less than 250 eggs/g. Number of adult H. contortus in the abomasums was also significantly reduced at all dose levels. Percentage of female worms surviving in the abomasums was reduced in COWP treated lambs. Liver copper levels increased linearly with increasing COWP dose, but no signs of Cu toxicity were evident in the lambs.

Based on these studies, use of COWP particles appears to have excellent potential for reducing parasite burdens in sheep. Data on goats have not yet been analyzed.

Economic Analysis

Data from LSU FAMACHA work showed that total number of dewormings of Research Station sheep for the Haemonchus season in year 2 was reduced to 8, while anthelmintics were used on the same animals approximately 150 times in year 1. This represents a direct savings in anthelmintic costs. Labor costs were not calculated at the LSU Research Station. At the USDA Booneville Research Station, with the use of FAMACHA in year 2, anthelmintics were used 67 times compared to 298 times for the same flock the previous year. Less than 1 % of the Research Station sheep required 3 treatments, 10.7 % required 2 treatments, 32.2 % required 1 treatment, and 56.4 % required no treatments. Data from FVSU are currently being compiled. Year 3 of the project will be the year for full economic analysis. This will include direct cost savings due to reduced number of treatments for GIN infection, but also indirect savings due to reduction in the rate of development of anthelmintic resistance within the herd or flock.

Impacts and Contributions/Outcomes

Impact /Outcomes

1. Established that differential color of eye membranes provide definitive suggestions of which animals in and herd or flock are most at risk from GIN infection and will benefit from treatment with effective anthelmintic.

2. Data from previous studies and data collected in this project have established that all anthelmintics are not equally effective in controlling GIN infection in all herds or flocks.

3. An increased awareness of the need for proactive and intentional strategic GIN management in sustainable production systems was created through our Smart Drenching Workshops.

4. Results from university and USDA Station research suggest that biological interventions to GIN control have potential in augmenting the use of chemical agents that are becoming marginal in effectiveness.

5. Findings are allowing extension specialists to be more precise and definitive in making management recommendations and in collaborating with veterinarians in developing GIN control plans for clients.

Contributions

Project-related presentations

Additional FAMACHA and Smart Drenching presentations

Kaplan, R.M., “Emerging Issues in the Control of Gastrointestinal Nematode Parasites”, 140th Annual Convention of the American Veterinary Medical Association, Denver, CO, July 19-23, 2003.

Kaplan, R.M., “New Concepts in Parasite Control: Smart Drenching and FAMACHA”, 140th Annual Convention of the American Veterinary Medical Association, Denver, CO, July 19-23, 2003.

Kaplan, R.M., “Parasitology For The Equine Practitioner: Past, Present and Future”, Arizona Veterinary Medical Association – Equine Meeting, Phoenix, AZ, September 9, 2003.

Kaplan, R.M., “Equine Anthelmintics: Overview of Drug Characteristics and Considerations in Choice”, Arizona Veterinary Medical Association – Equine Meeting, Phoenix, AZ, September 9, 2003.

Kaplan, R.M., “Emerging issues and new concepts for nematode parasite control in small ruminants”, 107th annual meeting of the United States Animal Health Association, San Diego, CA, October 9-16, 2003.

Scientific presentations

Kaplan, R.M., S.B. Howell, L.L. Mortensen, L.H. Williamson, T.H. Terrill, and M. Larsen, “Comparison of fecal egg count reduction test and DrenchRite© larval development assay for detection of anthelmintic resistance on goat farms”, American Association of Veterinary Parasitologists, 48th Annual Meeting, Denver, CO, July 18-21, 2003.

Terrill, T.H., J.E. Miller, R.M. Kaplan, M. Larsen, R.A. Kircher, O.M. Samples, S. Gelaye, “Epidemiology of goat gastrointestinal nematodes in Georgia”, World Association for the Advancement of Veterinary Parasitology, 19th International Conference, New Orleans, LA, August 10-14, 2003.

Watkins, A.D., J.E. Miller, T.H. Terrill, M. Larsen, R.M. Kaplan, “Effectiveness of copper-oxide wire particles on the control of Haemonchus contortus in sheep”, World Association for the Advancement of Veterinary Parasitology, 19th International Conference, New Orleans, LA, August 10-14, 2003.

Larsen, M., T.H. Terrill, O. Samples, S. Husted, J.E. Miller, R.M. Kaplan, S. Gelaye, “Potential of the fungus Duddingtonia flagrans to control nematodes in goats in southeastern United States: a dose-titration and dose-timing study”, World Association for the Advancement of Veterinary Parasitology, 19th International Conference, New Orleans, LA, August 10-14, 2003.

Publications related to the project

Scientific

Fontenot, M.E., Miller, J.E., Peña M.T., Larsen, M., and A. Gillespie. 2003. Efficiency of feeding Duddingtonia flagrans chlamydospores to grazing ewes on reducing availability of parasitic nematode larvae on pasture. Vet. Parasito.l 118, 203-213.

Kaplan, R.M., “Emerging Issues in the Control of Gastrointestinal Nematode Parasites”, in Proceedings of the 140th Annual Convention of the American Veterinary Medical Association, Denver, CO, July 19-23, 2003.

Kaplan, R.M., “New Concepts in Parasite Control: Smart Drenching and FAMACHA”, in Proceedings of the 140th Annual Convention of the American Veterinary Medical Association, Denver, CO, July 19-23, 2003.

Mortensen, L.L., L.H. Williamson , T.H. Terrill, R. Kircher, M. Larsen and R.M. Kaplan, 2003. Evaluation of prevalence and clinical implications of anthelmintic resistance in gastrointestinal nematodes of goats. JAVMA, 223(4):495-500.

Pena, M.T., Miller, J.E., Horohov, D.W., 2004. Effect of dexamethasone treatment on the immune response of Gulf Coast Native lambs to Haemonchus contortus infection. Vet. Parasitol. 119: 223-235.

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 timing studies. Vet. Parasitol. 120:285-296.

Scientific – submitted/in press

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 FAMACHA© eye color chart for detecting clinical anemia in sheep and goats on farms in the southern United States (submitted Veterinary Parasitology).

Burke, J.M., and J.E. Miller. 2004. Resistance to gastrointestinal parasites in Dorper, Katahdin, and St. Croix lambs in the southeastern United States. Small Rum. Res. (In Press).

Abstracts

Burke, J.M., and J.E. Miller. 2004. Dose of copper oxide wire particles (COWP) and feed supplement level influences Haemonchus contortus infection in lambs. Ann Meet So Sect Amer Soc Anim Sci: No. 117.

Terrill, T.H., Kaplan, R.M., Larsen, M., and J.E. Miller. 2003. Emerging issues in the control of nematode parasites in goats: anthelmintic resistance and biological control using nematophagous fungi. J Anim Sci 80 (Suppl. 1): 144.

Terrill, T.H., Miller, J.E., Kaplan, R.M., Larsen, M., Kircher, R.A., Samples, O.M., and S. Gelaye. 2003. Epidemiology of goat gastrointestinal nematodes in Georgia. Proc 19th Inter Conf World Assoc Advance Vet Parasitol: 188.

Watkins, A.D., Miller, J.E., Terrill, T.H., Larsen, M., and R.M. Kaplan. 2003. Effectiveness of copper-oxide wire particles on the control of Haemonchus contortus in sheep. Proc 19th Inter Conf World Assoc Advance Vet Parasitol: 198.

Popular press publications

“Worms got your goat? Here are some tips to help you prevent parasite resistance”, John Leidner, Progressive Farmer, Vol. 118, No. 8, September 2003, p.30. (R. Kaplan – consultant to article)

Collaborators: