Final Report for LNC08-306
This two-year, on-farm research project sought to determine the usefulness of a non-traditional forage, forage chicory (Cichorium intybus L.), in controlling gastrointestinal nematode parasites (GIN) in grazing sheep. A comparison forage, brown mid-rib forage sorghum (Sorghum bicolor (L.) Moench.) x sudangrass (Sorghum sudanense Piper) hybrid (BMR) was used to provide a comparable forage to provide a low, or no, parasite challenge. The work was conducted on three farms in different areas of our state with different soil types and management systems. Two groups of 20 lambs each, consisting of animals of similar age, weight, sex, birth type, body condition score, and FAMACHA score, were identified at each farm, and these animals were strip grazed across these forages for period of 12-21 days. Fecal worm egg count (FEC) was determined for each animal at the beginning and end of each grazing period along with determinations of weight, body condition score, and FAMACHA score. Forage samples were taken at the beginning and end of each grazing period and were analyzed for nutritive value as well as sesquiterpene lactone (SL) content of chicory. It is believed that the SLs in chicory may have antiparasitic activity. Statistical analysis of the data collected over the two-year period revealed that during the respective grazing periods, lambs grazing the BMR gained slightly more weight than the lambs grazing the chicory, but the FEC of the lambs grazing the chicory increased less than those grazing the BMR. We believe that this suggests that the antiparasitic effect of chicory was attributable to a direct effect on GIN. When lambs grazed each forage for about two weeks, the effect of this cultivar of forage chicory on GIN parasitism was minimal and probably of low biological importance. There was no difference between the groups with respect to body condition score, FAMACHA score, or parasite species in the FEC (larval cultures consistently revealed 70-90% Haemonchus contortus).
We observed that chicory (cultivar: Forage Feast) was somewhat difficult to establish in the spring because of annual weed competition, but it was able to provide high quality nutrition. Wintertime freeze/thaw cycles pushed the tapered chicory root out of the ground at varying degrees on all three farms resulting in loss of plants and deterioration of the stand. We also observed on one farm, and suspected on another farm, that lambs refused to eat chicory plants in some areas of the field. Our initial assumptions were that the ungrazed areas would be higher in SL content than the grazed areas. The results of SL analysis of grazed areas and areas where plants were not eaten contradicted our assumptions. Forage from grazed areas had nearly twice as much SL as the forage from the ungrazed areas. The reason for this difference is not known. Ungrazed areas were randomly distributed and did not correspond to areas where animals had congregated during the previous grazing pass. The lambs may have learned to associate the bitter taste of SL with improved health status during their first grazing pass and grazed selectively during the subsequent pass to self medicate, but this is speculative. The BMR was also able to provide high quality nutrition, but plants mature quickly and their nutritive value declines rapidly. This means that the window of time when this forage is best suited for young growing lambs is narrow, 10-14 days, making it a difficult forage to manage.
We have disseminated these results to farmers, students, veterinarians, and researchers using face-to-face workshops, web programming, field days, presentations at forage and grazing conferences, and publication in professional journals.
Sheep farms that utilize managed grazing are both economically profitable and environmentally sustainable. In our region, perhaps the greatest threat to this production system is gastrointestinal parasites, especially the blood feeding Haemonchus contortus. Loss of productivity associated with parasite infections is usually more costly to the farmer than animal deaths, although mortality attributed to parasite infection can be significant too. Since the 1960s, farmers have relied almost solely on treatment with chemical dewormers to minimize deaths and maximize production. Although this approach has been very successful until recent years, worm resistance to every available dewormer chemical class has now been documented across much of the USA, including Ohio.
In recent years, a great deal of interest has been generated in the use of plants which contain anti-parasitic compounds such as condensed tannins (CT) or sesquiterpene lactones (SL). The plant which has received the most attention in the USA is sericea lespedeza (Lespedeza cuneata [Dum.-Cours.] G.Don). Some varieties of this plant have proven activity against adult parasites (reduced parasite numbers, reduced egg production) and larvae (failure to establish in the abomasum). Much of this research was conducted in the southern United States. However, many varieties of the plant are unpalatable to cattle and sheep, probably because of its high condensed tannin content. It is difficult to manage in many grazing systems, and it does not support good weight gains or milk production compared to some other forages commonly grazed in our region. It has been difficult to establish in the central Appalachian hill lands although some varieties appears to grow readily in several counties in southeastern Ohio on reclaimed coal mine land. In many states sericea lespedeza is considered a noxious weed as it is difficult to control once established.
Other plants with anti-parasitic properties have been investigated for their potential to support livestock production in other regions of the world. Among these are varieties of forage chicory.
Chicory contains SL and small amounts of CT, and it has been shown to have negative effects on the survival of adult and larval stages of internal parasites of sheep and farmed deer in research conducted in other countries. Published research suggests that the SL concentration is likely the principal factor affecting parasite numbers although this is still incompletely studied. In one study, there also appeared to be a direct negative effect of chicory sward or plant structure on development/survival/migration of the larval forms of parasitic sheep nematodes aside from the effects of any plant-derived anti-parasitic metabolites in the abomasum and intestine, which may reduce overall parasite infection in the animals. The use of chicory as forage for ruminants has been investigated in our region in PA, WV, and OH, but there are limited published reports of attempts to investigate the possible anti-parasitic effects of chicory in the USA. Although at least a half dozen forage chicory cultivars are now available, only Grasslands Puna has received intensive investigation – predominantly in work conducted outside the USA. Research in Dr. Foster’s laboratory showed that the cultivar, Forage Feast, contained the highest concentrations of total SL among several studied. This cultivar was chosen for this project for this reason and because it is readily available in the USA.
This two-year project examined the use of forage chicory in comparison with BMR, a nutritious forage not known to have direct activity against internal parasites, as part of a GIN control strategy in sheep. Specifically the objectives were to:
• evaluate and document the establishment of several acres of forage chicory and BMR;
• measure forage tonnage produced and the nutrient content of chicory and BMR;
• track animal performance on forage chicory and BMR with periodic weighing;
• evaluate and compare the effectiveness of chicory and BMR in controlling or reducing parasite load by comparing pre- and post-grazing fecal egg counts and changes in FAMACHA scores; and to
• analyze chicory samples for sesquiterpene lactone composition at the beginning and end of each period of grazing.
Three participating sheep farms were identified. They were located in Athens, Knox, and Wayne Counties in Ohio and represented differing soil types and management systems. Forage chicory was established in 5-acre plots on each farm in May of 2009. BMR was planted in early June in both 2009 and 2010, and forages were ready for the first grazing in early July. Between March and May in 2009, manure samples were collected from animals at each farm and submitted to the University of Georgia for DrenchRite Assay to determine dewormer susceptibility profiles for the major worm parasites on each farm. On each farm 40 weaned lambs were identified with similar age, weight, sex, birth type, body condition score, and FAMACHA score. These were divided into two groups of 20 animals each and ear tagged and paint branded for identification. The animals remained in their groups for the grazing season. Condition score, weight, and FAMACHA score were determined for each animal at the beginning of each grazing period and a fecal sample was taken from each lamb. Each group grazed their respective treatment forage for about 15 days. At the end of the grazing period, lambs were condition scored, FAMACHA scored, and weighed again, and a fecal sample was again taken for FEC. In 2010, blood samples were also taken from each lamb before and after each grazing pass to determine packed red blood cell volume (PCV), a measure of anemia, to compare with the FAMACHA score. Animal records were maintained in a computer spreadsheet. At the end of a grazing pass, animals were comingled and grazed on a grass/legume pasture for approximately three weeks until the treatment forages had re-grown to a point where they could be grazed a second time.
Samples from each forage plot were taken at the beginning and end of each grazing pass and submitted for nutrient analysis as well as quantitative SL analysis for the chicory. In addition, an estimate of forage tonnage available at the beginning of the grazing pass was determined as was an estimate of plant composition of the stand. At the end of the grazing pass, an attempt was also made to determine the botanical composition of what the animals ate.
Fecal samples from each lamb were individually submitted to egg counting using a quantitative McMaster procedure, and a portion of each sample was also pooled for worm larvae culture at both the beginning and end of each grazing pass. Larvae were harvested from the culture after 7-10 days and a representative sample was subjected to microscopic species identification to determine species of worms infecting the lambs and relative proportions. Fecal consistency scores were also determined for each sample according to a scale described in a previously published report. These scores were was used to adjust respective FEC for moisture content.
All animal data were analyzed using a linear mixed models analysis adjusting for farm, year, grazing pass, sex, treatment group, and initial FEC. Spearman correlation coefficients were also calculated for the animal level data examined.
All animal and forage data were collected in the 2009 and 2010 grazing seasons and ended in mid-September 2010. Statistical analysis and educational activities related to the project were conducted in late 2010 and through the fall of 2011. All three farms had dewormer-resistant populations of worms as demonstrated by the DrenchRite Assay in 2009 and later verified in some cases by fecal egg count reduction testing. All three farms had resistance to the benzimidazole class of dewormers. One farm had resistance to levamisole and ivermectin leaving only moxidectin as an effective dewormer on this farm. The other two farms had worm populations sensitive to levamisole, and DrenchRite Assay indicated susceptibility to ivermectin and moxidectin. However, subsequent fecal egg count reduction testing on these two farms showed that ivermectin only gave an 85-90% reduction in egg counts. This is a useable efficacy but indicates low resistance to this chemical.
Statistical analysis of the data collected over the two-year period revealed that during the respective grazing periods, lambs grazing the BMR gained slightly more weight than the lambs grazing the chicory although the nutritive value of the forages was similar. Because lambs were on naturally contaminated pastures prior to the start of grazing the treatment forages on all farms in both years, they had acquired a worm burden, and it was largely from consumption of overwintered parasite larvae on the spring forages they grazed. The significance of this observation is that worm larvae acquired from those pastures would not be mature and producing eggs for at least 19 days after the lambs’ last exposure (this is the “prepatent period” for the worms). Consequently, if the treatment forages had no effect on parasites or their egg output, we would expect to see an increase in the lambs’ FEC over the duration of grazing the treatment forages. In fact this occurred in all grazing passes, but the FEC of the lambs grazing the chicory increased statistically less than those grazing the BMR. Given the slightly superior weight gain in the BMR lamb groups, this suggests that there was an antiparasitic effect on the GIN in the lambs grazing chicory, at least with regard to their egg output, and that this is likely due to a direct effect of chicory on the worms as opposed to merely an effect of improved nutrition for chicory as has been suggested in a few other studies. However, under the conditions used in this project where lambs grazed each forage for about two weeks, the effect of this cultivar of forage chicory on lowering FEC was low and probably of minimal biological importance. It is important to note that on two farms we were not able to establish pure stands of chicory because of annual weed competition; chicory composition was approximately 50-69%. Thus, our results may have been influenced by dilution of the chicory intake with other plants. Nevertheless, we believe our experiences reflect what may be realistic expectations for establishment of this plant in our region.
There was no difference between the groups with respect to body condition score, FAMACHA score, or parasite species in the FEC (larval cultures consistently revealed 70-90% Haemonchus contortus) at the end of grazing passes. The fact that we balanced the groups on body condition and FAMACHA scores at the beginning of the project, and no lambs with condition scores of less than 2 (1-5 scoring system) or FAMACHA scores above 2 (1-5 system with 1 representing normal and 5 representing severe anemia) were enrolled in the groups may have prevented our seeing a difference if one existed. The correlations between FAMACHA and FEC (r=0.09) and FAMACHA and PCV (r=-0.09) were low and this too may have been biased by our assignment of animals to groups with only scores of 1 or 2 thus making it difficult to detect a relationship. Correlation between PCV and FEC was highly significant and good (r=-0.45), and this may reflect the more objective nature of PCV measurement for anemia versus the subjective nature of FAMACHA scoring and the fact that lambs may be more difficult to score than ewes.
We observed that chicory (cultivar: Forage Feast) was somewhat difficult to establish in the spring because of annual weed competition, but it was able to provide high quality nutrition. Wintertime freeze/thaw cycles pushed the tapered chicory root out of the ground at varying degrees on all three farms resulting in loss of plants and deterioration of the stand. We also observed on one farm, and suspected on another farm, that lambs refused to eat chicory plants in some areas of the field. Our initial assumption was that the ungrazed areas would be higher in SL content than the grazed areas because of the bitterness of SL influences palatability. The results of SL analysis of grazed areas and areas where plants were not eaten contradicted our assumptions. Forage from grazed areas had nearly twice as much SL as the forage from the ungrazed areas. The reason for this difference is not known. Ungrazed areas were small and randomly distributed and did not correspond to areas where animals had congregated during the previous grazing pass. Sesquiterpene lactones are believed to have anthelmintic properties. The lambs may have learned to associate the bitter taste of SL with improved health status during their first grazing pass and grazed selectively during the subsequent pass to self medicate, but this is speculative at this time. The BMR was also able to provide high quality nutrition, but plants mature quickly and their nutritive value declines rapidly. This means that the window of time when this forage is best suited for young growing lambs is narrow, 10-14 days, making it a difficult plant to manage. During this project, we scheduled grazing passes to correspond with the period of high nutritional value.
In January of 2011, all the project team, including farmers, met to discuss the results of the project and what we believed we had learned. Overall, we concluded:
• FAMACHA use must be correlated with record keeping and analysis; farmers must take time to look at trends in the animals that are being FAMACHA scored; FAMACHA can be an early warning system of approaching trouble with Haemonchus.
• FAMACHA is a great tool but probably cannot be used as the only selective deworming or management strategy in large flocks because of the labor requirement.
• Lambs can be difficult to FAMACHA score correctly; our impression is that they may be somewhat paler than the PCV indicates in the middle range FAMACHA scores (2 and 3). This may lead to unnecessary treatment, but it is the most conservative approach and safeguards animal welfare while still leaving a large portion of the animals untreated. Leaving some animals untreated slows the development of dewormer resistance.
• The message of parasite biology and lifecycle needs to be repeated and heard numerous times before it is understood well enough for farmers to make independent management decisions.
• Overall, the use of annual forages as a necessary component of parasite management may be difficult to implement on many farms. Stand establishment and timing is very weather dependent; topography and soil type will limit the acreage that can be used for annuals.
• It is critical for a farmer to know what the farm profile is on parasite dewormer resistance because designing a forage-based management system that does not require at least some selective use of dewormers will be very difficult for most farmers.
• On-farm research can positively affect the practices of the farmer and the experience base of all of the persons associated with the research.
• The use of management practices and forages with various benefits for parasite control can help extend the effective life of dewormers.
With respect to various management strategies we observed:
• Overwintered third stage larvae of Haemonchus contortus) on pastures must be a management consideration through the month of June in Ohio. On two farms and in two years we experienced severe Haemonchus infections in lambs in early July that could have only been the result of consuming overwintered larvae on permanent pastures prior to the chicory/BMR grazing. These farms had used strip grazing with a back fence, limited the grazing of animals (lactating ewes and lambs) to no more than 3-4 days on a strip, and avoided grazing of regrowth on strips animals had previously grazed. These practices prevented the animals from acquiring worms developing from eggs shed in the springtime. We hope to publish this finding as it represents exception to the current belief about poor survival of this worm’s larvae over winter in our area.
• Lambs grazed during lactation can be weaned at 60 days and be expected to have normal grazing behavior. They will subsequently need high quality nutrition to maintain acceptable performance and maintain reasonable resilience to parasite challenge.
• Egg shedding by ewes drops off rapidly at weaning; earlier weaning and separating ewes from lambs can reduce overall pasture contamination and allow grazing strategies tailored to the needs of lambs. Shortening up the time the ewes are lactating can lower the farm pasture contamination.
With respect to our observations of the forages grazed on these farms during the project we concluded:
• Chicory is a high quality feed for lambs; however, chicory is difficult to establish and maintain in some soils. Chicory should be planted with other legumes, such as a non-competitive clover variety, to help with nitrogen supply to chicory and impede frost heaving of chicory plants and competition from weedy plant species.
• Chicory can be frost seeded as long as there is low competition from other plants in the spring. (This was done in the early spring of 2010 on two farms to help replace the plants lost by frost heaving.) Bolted plants may produce enough seed to reseed the field to some extent, assuming there is not high sod competition. We need more observation on this.
• Chicory is good alternative forage, but some cultivars may be less palatable and more prone to frost heaving (such as Forage Feast). Palatability or preference may be animal species dependent. Soil environment may also affect palatability; this needs more study. Curt Cline observes that the Oasis cultivar (planted for another project in 2007) bolted more (number of stems/plant, number of bolted plants, onset and duration of bolting during the grazing season) than Forage Feast on his farm. This is not necessarily true at other locations. He also observed less frost heaving losses for this cultivar compared to Forage Feast on his farm in southeastern Ohio. SL composition of Oasis is quite different from that of Forage Feast and the various SLs may differ in their activity against GIN.
• Brown mid-rib sorghum/sudan grass (BMR) produces a high quantity of forage in a short period of time following establishment, and it is easier to establish than chicory.
• Although BMR can be a highly nutritious feed for lambs, the window of time it stays in the highly nutritious state is very short thus making it very difficult to manage correctly for growing lambs. It may be more suitable forage for other classes of animals with less demanding nutritional requirements, such as non-lactating ewes.
• Because BMR is seeded into a tilled soil (which helps with parasite control) and sheep will graze the leaves (high off the ground), the first grazing of a BMR seeding will provide parasite larvae-free forage. However, if annual grasses and broadleaf plants are present in the field, sheep may acquire larvae from these in subsequent re-grazing of the same area.
We learned a great deal about the usefulness of the forages we used in this project as well as how we might apply some additional grazing strategies. These experiences have been shared in numerous farmer-oriented Extension meetings conducted in 2011 and 2012 including an internet-based meeting held in February 2012 that reached an audience of over 250 people at 10 locations in Ohio and Kentucky. (see additional outreach and educational efforts in the Publications/Outreach section).
All three farms have updated information about drug resistant parasites on their farms and have changed their parasite control strategies for 2011 and 2012 based on observations made and new insights gained during these past two years. At one farm, they acquired some Katahdin (greater resistance to parasites) rams in the fall of 2010, and following implementation of a plan developed in December, 2010, they plan to monitor the crossbred offspring in 2011 and 2012 to determine if any genetic resistance to internal parasites can be measured in the progeny compared to their other sheep. This is part of a long term strategy to maintain sustainability of the sheep enterprise at this farm.
At the second farm, a purebred farm, a plan to begin selecting parasite-resistant sheep from their purebred animals has begun. In addition, they too have begun a crossbreeding program using Florida Native rams (a more parasite resistant breed) to develop a new commercial crossbred line with greater resistance to GIN. This effort has now become a consortium including 4 additional farms in Ohio and Michigan.
Because only moxidectin works well on the third farm, that farm has developed other approaches to selective deworming of ewes and lambs, and they plan to continue weaning lambs at an early age to facilitate their management. In 2012 that farmer plans to investigate strip grazing corn with lambs beginning in July because corn may provide better nutrition than BMR and be easier to manage. This will provide worm-free forage through the summer months.
On-farm research involves farmers who are effective in facilitating adoption of research outcomes by other farmers.
This research was not designed to evaluate the economic value of controlling parasites with chicory or annual forages. We do have estimates of the cost of establishing these two forages including fertilizer supplementation. Realistically, Ohio farmers should be able to expect a good chicory stand to provide high quality forage for at least 3 years. The minimal antiparasitic effects we observed in this project for chicory make us question if the benefits exceed the cost over using other nutritious forages. Perhaps other cultivars might give a different result (see Areas Needing Additional Study). BMR can be used as a parasite-free annual forage, for at least the first grazing, but is difficult to manage for growing lambs.
A survey of the participants in the educational activities conducted in August of 2011 (the three internet-based meetings and the field day) which featured several aspects of our project was conducted in the fall of 2011. We developed a survey instrument designed to evaluate the participants’ interest in presenting educational programming using this technology and approach, their satisfaction with the educational program, and their plans for the future with regard to parasite control. Results of this survey have been uploaded. Registrants from 14 different states participated in at least part of the programming. The majority were from Ohio (85.5%) followed by Pennsylvania (2.9%), Florida (2.2%), and Michigan (2.2%). The remaining states represented < 1% of the total participants and included: Colorado, Georgia, Iowa, Illinois, Indiana, Louisiana, South Dakota, Utah, Wisconsin, and West Virginia. Fourteen of the registrants indicated that they were veterinarians. The survey instrument was mailed to a total of 138 individuals in October, 2011, and 50 were returned for a response rate of 36%. The survey results were summarized in January 2012. Although demographic information was collected on the survey instrument, the responses were anonymous. Of the respondents 90% were farmers, 8% were veterinarians, and 2% were students.
Among the results relevant to this section of our final report: 93% of respondents indicated that this approach (internet-based meetings, face-to-face meetings, topped off by a field day) was a good educational approach; 95% of respondents said that they thought that the program would help them to better control parasites in their animals; and 93% of respondents would recommend the recorded meeting sessions to others as a useful resource in developing their parasite control strategy. Regarding their future plans: 100% of respondents indicated that they agreed or strongly agreed with the statement “I intend to apply my knowledge gained as a result of this program.”; 84% of respondents agreed or strongly agreed with the statement “I believe that I can increase my income as a result of this program.”; and 78% of respondents agreed or strongly agreed with the statement “I believe I can expand my operation as a result of this program.” Please see the uploaded document for the full survey results.
Educational & Outreach Activities
On May 17, 2011, we took 28 veterinary students from the OSU Food Animal Club to the Curt Cline farm for a discussion of our project and parasite control in small ruminants in general. We rented a bus and had a presentation/discussion session on the way to the farm (about 2 hour drive). We walked various fields on the farm, including forage chicory, and Mr. Cline presented what he had learned about parasite control and forage management during the previous 5 years from this project and others. After lunch, we visited another sheep farm in the area and discussed the parasite control program at that farm. Lastly, we visited a goat dairy farm where the farmer markets all his milk as handmade cheese. We discussed the special problems of parasite control in a dairy goat setting.
On August 4, 18, and 25 we delivered internet-based educational programs to a wide audience. The topics covered were: 1) Basic Parasite Biology and Control; 2) Parasite Management: Lessons Learned and Farmer Applications; and3) Management Tools and Techniques. We discussed what we had learned in our project in 2009 and 2010 as well as other information about parasite control. The meetings were held with a presenter-to-farmer audience in Mt. Vernon, Athens, and Wooster, Ohio, (on the three different nights) with the internet used to transmit the presentation via WebEx to 4 additional locations. The meetings qualified for continuing education credits for veterinarians who were also invited. In addition, the programs were advertised to a wide audience and farmers and veterinarians could preregister and participate in the meetings from their homes by logging in to WebEx. Over 120 people participated in one or more meetings or the subsequent field day. The registrants included residents of multiple states and also included 15 veterinarians who were mostly from Ohio but also the states of Indiana, Pennsylvania, Louisiana, South Dakota, and Florida. The presentations for the internet-based meetings were recorded and are available at: http://vet.osu.edu/extension/sare/parasite_control .
On August 27, we held a field day at the Summer Hill Farm (John and Jim Anderson), and 85 registered for the field day. The field day featured presentations on parasite control and visits to the farm’s fields for discussions of grazing strategies and use of alternate forages including chicory and BMR (see brochure). Each of our participating farmers took part in delivering the presentations and discussing things they had learned about parasite control.
A poster was prepared for the Buckeye Shepherd’s Symposium held on December 10, 2011. It described the project, results, and observations. Attendance for the Symposium was over 250. The poster was used again at the Ohio Ecological Food & Farm Association’s annual conference held February 18 and 19, 2012. We anticipate continued use of this poster.
We have planned several Extension fact sheets resulting from this work. One is published, one is nearly done, and three more are in various stages of completion. We are writing a manuscript to be submitted to Veterinary Parasitology describing the chicory work and are preparing another short communication describing our observations of overwintered Haemonchus contortus larvae. A third paper describing plant analyses and other aspects of lambs’ refusal to eat chicory at the Cline farm in 2010 is being written for submission to the Journal of Agricultural and Food Chemistry.
Below is a listing of publications and presentations thus far:
• McCutcheon, J., Shulaw, W., Foster, J., Cooper, T., Rickard, B., and Wittum, T. 2010. Cultivar Preference of Lambs Grazing Forage Chicory in Ohio [Abstract]. 2010 American Forage & Grasslands Council, Proceedings & Abstracts. Springfield, MO. (June 21)
• Shulaw, W., Lewandowski, R., McCutcheon, J., Cline C., Foster, J., & Wittum, T. 2009. Non-traditional forages in a managed grazing system for control of gastrointestinal parasites in sheep: preliminary work. [Abstract]. 2009 Annual Meeting, American Forage & Grasslands Council on CD-ROM. Grand Rapids, MI.
• Foster, J., Cassida, K., Turner, K., Sanderson, M., Shulaw, W., McCutcheon, J., Cooper, T., Parish, J., & Rosskopf, E. 2009. Plant constituents: Opportunities to control Haemonchus contortus. In: Appalachian Workshop and Research Update
Improving Small Ruminant Grazing Practices Proceedings. Beaver, WV: 33-52.
• Foster, J. G., Cassida, K. A., Turner, K. E., Sanderson, M. A., Shulaw, W. P., McCutcheon, J. S., Cooper, T. A., Parish, J. R. and Rosskopf, E. N. Plant constituents: Opportunities to control Haemonchus contortus, pp. 33-45. In Morales, M. R. (ed.) Improving Small Ruminant Grazing Practices, Proceedings of the Appalachian Small Ruminant Grazing Workshop, July 11, 2009, Beaver, WV. 2009. (Conference Proceedings)
• Foster, J. G., Cassida, K. A., Sanderson, M. A., Shulaw, W. P., McCutcheon, J., Cooper, T. and Parish, J. R.. Chicory cultivars differ in sesquiterpene lactone composition. In Proceedings of the American Forage and Grassland Council 2009 Annual Conference, June 21-23, 2009, Grand Rapids, MI. CDROM. 2009. (Conference Proceedings)
• Foster, J. G., Cassida, K. A. and Turner, K. E. Anthelmintic potential of chicory forage is influenced by sesquiterpene lactone composition. In Proceedings and Abstracts of the American Forage and Grassland Council, June 21-23, 2010, Springfield, MO. CDROM. 2010. (Conference Proceedings)
• Foster, J. G., Cassida, K. A. and Turner, K. E. 2011. In vitro analysis of the anthelmintic activity of forage chicory (Cichorium intybus L.) sesquiterpene lactones against a predominantly Haemonchus contortus egg population. Vet. Parasitol. 180:298-306.
• Foster, J. G., Cassida, K. A., Sanderson, M. A., Shulaw, W. P., McCutcheon, J. S., Cooper, T. A., and Parish, J. R. Sesquiterpene lactone composition varies among forage chicory cultivars. For Forage and Grazinglands ( to be submitted May 2012)
• McCutcheon, J., Shulaw, W., Lewandowski, R. and Foster, J. 2012. Forages for parasite control in Sheep [Abstract]. Proceedings and Abstracts 2012 Annual Conference American Forage and Grasslands Council. Louisville, KY
• McCutcheon, J., Shulaw, W., Lewandowski, R., and Foster, J. 2012. Lambs Infected with Barber Pole Worms Selectively Grazed Chicory with High Concentrations of Sesquiterpene Lactones. [Abstract]. Proceedings and Abstracts 2012 Annual Conference American Forage and Grassland Council. Louisville, KY
Areas needing additional study
Our project was carried out using the Forage Feast cultivar of chicory because it is readily available in the USA and because published work at the time of the proposal and initiation of the project indicated that it had the highest concentration of total SL of several known cultivars. If SL are indeed the compounds in chicory responsible for antiparasitic effect, we believed that use of Forage Feast might optimize our ability to detect an antiparasitic effect. During the second year of our on-farm work, using in vitro techniques in the laboratory, Dr. Foster demonstrated that total SL levels in the plant may not be as important as the concentration of one of the three major fractions, 8-deoxylactucin. In that work, egg hatching of Haemonchus contortus was examined in the presence of extracts of both Forage Feast and Grasslands Puna. In Grasslands Puna, the predominant SL (8-deoxylactucin) was associated with reduced egg hatching while the predominant SL in Forage Feast (lactucin) had little effect (Vet. Parasitol. 180:298-306). Although this finding might help explain why we saw minimal effect of Forage Feast chicory grazing on FEC, more study using different cultivars is needed in actual animal studies to evaluate direct effects on worms or worm larvae being consumed by animals.
We chose a period of grazing lasting about 2 weeks for our study as other studies looking at chicory and the CT of sericea lespedeza have used this approach as well. It is possible that longer periods of grazing chicory would have a more profound effect than we observed. However, our study is the first to demonstrate the potential value of chicory in actual on-farm trials under typical farm management conditions. It also illustrated the practical problems of establishing and maintaining this forage in our region, and we did gather useful information about selective grazing of this plant that we hope to publish.