Use of Forage Chicory in a Small Ruminant Parasite Control Program

Internal parasites can limit profitability in pasture-based small ruminant production systems. Haemonchus contortus, also known as the barber pole worm, is the parasite of greatest concern in Ohio. It causes poor weight gains and lowered milk production. Its blood-feeding activity can lead to severe anemia and death of the host animal. Animals with higher nutritional needs, lactating ewes, and lambs less than 8 months of age are particularly susceptible to heavy worm infections. Chemical dewormers (anthelmintics) have been used extensively to control internal parasite infections, but these products are becoming less effective because the parasites have developed resistance to them. Numerous studies conducted on U.S. sheep and goat farms have documented the resistance of H. contortus to all of the classes of dewormers available in the U.S. market. We need viable parasite control strategies that minimize the use of dewormers. Forage chicory may be a tool in the development of these strategies.

Some research, conducted principally outside the United States, has indicated certain compounds in forage chicory may have harmful effects on internal parasites of sheep and goats resulting in improved animal performance, reduced worm burdens, and possibly reduction in worm egg production. These compounds are secondary plant metabolites called sesquiterpene lactones. Preliminary on-farm research conducted in Ohio in 2007 supported these observations. During the summers of 2009 and 2010 funding provided by a NCR SARE Research and Education grant permitted the investigation of the use of some non-traditional forages within a managed grazing system as a strategy to reduce the parasite burden in lambs. One of the forages we used was chicory.

Forage chicory is a perennial forb that produces large, upright leaves during spring, summer, and early fall (Photo 1). It has a deep taproot and heat tolerance allowing for continued growth during the summer months. Previous research in surrounding states indicates that forage chicory can be more nutritious forage than cool-season grasses and alfalfa. The most common varieties of forage chicory available in Ohio are Grasslands Puna, Forage Feast, and Oasis (a more cold-tolerant and disease-resistant variety developed from Grasslands Puna). Forage chicory was originally developed in New Zealand. Grasslands Puna is the oldest and most widely tested variety in the eastern United States. The forage chicory varieties INIA le Lacerta and La Niña, which originated in Uruguay, will persist in Ohio pastures for shorter periods than the previously mentioned varieties because they behave as biennials in our climatic region. These two varieties also have more fibrous root systems and they contain lower concentrations of sesquiterpene lactones.

Agronomic Considerations  

Forage chicory varieties that behave as perennials can survive between 3 and 5 years if well managed. Well-drained to moderately drained soils with medium to high fertility provide conditions for optimal growth. Both spring (March 15–April 15) and early fall (August) seeding have been successful. The Ohio Agronomy Guide recommends that soil pH be maintained above 5.5 for best results. Critical levels of soil phosphorus and potassium are 25 ppm and 110 ppm respectively. Similar to cool season grasses, the yield response of forage chicory is dependent upon nitrogen. The Ohio Agronomy Guide suggests split applications of nitrogen totaling between 100 and 150 lbs of actual nitrogen/acre annually to achieve maximum yields of dry matter (DM)/acre if legumes are not included in the mixture. The split applications would be three applications of 50 lbs of actual nitrogen per acre. One would be at spring green up, one in early summer after a grazing, and another in early fall.

Forage chicory should be planted in a tilled seedbed. A firm, finely textured seedbed is recommended for establishment. Drilling or broadcasting are both acceptable planting methods. Chicory should be planted to a depth of between 0.25 and 0.50 inch. If the seed is broadcast, then the soil should be prepared and cultipacked both before and after seeding to ensure adequate seed to soil contact.

The Ohio Agronomy Guide recommends a seeding rate of 6 lbs/acre for drilled plantings of pure stands. Forage chicory can be included in forage mixtures with legumes and/or grasses. It can also be frost seeded by broadcasting into pastures with exposed soils in late February and early March.

Management Options: Opportunities and Challenges

Forage chicory can grow rapidly during the months of July and August when temperatures can exceed 90 degrees F. It is productive during dry periods when growth of other forage species is limited. Depending upon the soil fertility and the amount of nitrogen available, total forage DM yield can be in the range of 3 to 5 tons/acre.

Forage chicory paddocks should be grazed when they are in a vegetative growth stage. Grazing should begin when the plants are 8 to 10 inches in height. The grazing pass should end when there is 1 to 2 inches of plant residual. This residual will allow for best plant recovery and rapid re-growth. With this type of management and good growing conditions, a grazing pass can be made every 14 to 21 days. Higher residuals or longer rest periods may allow the plants to produce flower stalks (bolting). 

As with any other pasture plant, nutritional quality is related to the stage of growth and maturity. A forage chicory plant at an 8 to 10 inch vegetative growth stage (Photo 2) is high quality forage. Plant crude protein (CP) levels in such forage will range between 10 and 32% (DM basis), depending upon the nitrogen available to the stand. Leaves have been shown to be up to 90% digestible. It is not unreasonable to expect that grazing lambs provided forage with this level of nutrient quality, in a pasture where few to no infective parasite larvae are ingested, will experience good weight gains. The high moisture content of chicory leaves (85%), however, could limit forage DM intake.  

Once the chicory plant begins stem elongation toward flower and seed production (Photo 3), plant nutritive quality and palatability decline rapidly. Similar to other forages, the CP and total digestible nutrient (TDN) content of chicory decrease while fiber levels, as measured by acid detergent fiber (ADF) and neutral detergent fiber (NDF), increase with bolting. The tendency to bolt during the establishment year varies with forage chicory variety. All varieties will bolt readily in the second and subsequent seasons. Managing bolting after the establishment year is one of the main challenges in using forage chicory. Our experience in Ohio, working with forage chicory over the course of this and other studies, has been that the plant could advance from a high quality vegetative stage to bolting during the May to June time period. After bolting occurs, leaf production is slowed. Bolting can be managed by mowing during the stem elongation phase. This may sometimes be necessary between planned grazing passes, especially in midsummer when the rate of reproductive growth is rapid.

One approach to provide high quality chicory forage to grazing lambs or kids is to strip graze across a paddock with a high stocking density, moving animals to a new forage allotment frequently. Animal movement to a new allotment could be as frequently as less than a day up to every three days. The use of a back fence ensures that regrowth in grazed areas is not selected preferentially. This practice will facilitate plant recovery and eliminate exposure of animals to infective larvae of internal parasites left on strips grazed earlier in the pass.

The persistence of forage chicory depends on a healthy tap root. Frost heaving and subsequent plant death is a particular problem in pure stands of Forage Feast chicory, and exposed tap roots are easily damaged by grazing animals. Stand longevity is also decreased by overgrazing and excessive hoof traffic, so care in the determination of the number of animals allotted to a grazing area and the timing of animal movement is important.

Ohio On-Farm Results  

During the 2009 and 2010 growing seasons, the Forage Feast cultivar of forage chicory was grown on three farmer cooperator farms as part of a NCR SARE-funded Research and Education project to examine non-traditional forages in a managed grazing system for the control of gastrointestinal parasites in sheep. This cultivar was chosen for this project because research has shown that it typically produces higher amounts of sesquiterpene lactones, the compounds thought to be active against internal parasites in sheep and goats, than most other varieties. Its taproot is typically more thick and tapered than that of other varieties (Photo 4), but leaf dry matter production and nutritive quality is comparable to other varieties. All forage chicory cultivars contain three major sesquiterpene lactones; however, the dominant sesquiterpene lactone in Forage Feast is not the most prevalent sesquiterpene lactone in the other forage chicory cultivars.

The cooperators' farms were located in Athens, Knox, and Wayne counties in Ohio. Soil type and soil test values for the respective farms are listed in Table 1. The goal in 2009 was to get the forage established by the first of June. This planting schedule, combined with adequate soil moisture, provided forage ready to be grazed by mid-July. The intent of the study was to make two grazing passes through this forage with weaned lambs each year. Each grazing pass lasted 14 to 21 days, and animal measurements and fecal worm egg counts (FEC) were obtained for each animal in the test group. A comparison group of lambs was grazed on brown mid-rib sorghum sudangrass (BMR) which is a nutritious summer annual not thought to have any activity against internal parasites. (See OSU Extension fact sheet VME-30, "Use of a Brown Mid-Rib Sorghum x Sudangrass Hybrid in a Small Ruminant Parasite Control Program.")

Forage quality (CP, TDN, ADF, and NDF) and yield (DM) samples were taken at the beginning of each grazing pass. Analytical results, expressed on a DM basis for 2009 and 2010 are shown in Tables 2 and 3, respectively. The dates in the table refer to the beginning of each grazing pass by farm location listed by county.

Table 1: Soil type and soil test values on trial farms.

Table 2: Forage quality at the start of each grazing pass in 2009.

Table 3: Forage quality at the start of each grazing pass in 2010.

As the tables illustrate, there were delays in starting the initial grazing pass for two farms in at least one of the study years. These delays were unrelated to the forage chicory availability which was ready for grazing by early to mid-July on each farm in each year. In cases where the initial growth could not be used for the parasite study, the forage was harvested either by worm-free sheep or mechanically. Therefore, DM yield values in the tables do not reflect the total quantity of forage that could have been grazed in a more intensive management system. In addition, the DM yields do not reflect plant growth during the grazing pass. In July and August, DM accumulation per day was determined to be about 70 lbs/acre.

The design of the parasite study dictated when animals entered the forage chicory, how long it was grazed, and when animals would enter for another grazing pass. Timing from the animal side did not always match up with timing from a forage management perspective. This increased the difficulty of managing the grazing pass to provide adequate forage quality for the lambs during the entire grazing pass period. However, the tables provide a good picture of the potential yields and quality of forage chicory across several locations in Ohio with differing soil types and fertility.

Lessons Learned

Over the course of the two-year project, on-farm observations, conversations with farmer cooperators, and data collection and analysis provided some teachable moments. Some of the lessons we learned regarding the use of forage chicory for growing lambs include:

• Chicory is a nutritious forage for lambs.
• Chicory can be difficult to establish and maintain in some soils. Chicory should be planted with forage legumes, such as a non-competitive clover variety, to help provide nitrogen to chicory and impede frost heaving of chicory plants and competition from weedy plant species.
• Frost heaving can cause a significant loss of plants during some winters. This may be somewhat more pronounced with Forage Feast that has a very large tap root than with cultivars that have some fibrous roots in addition to a tap root (Photo 5).
• Spring-seeded chicory can have strong competition from weeds. Planting into a weed-free seedbed is crucial. There are few options for weed control.
• 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 chicory plants lost by frost heaving during the preceding winter. Frost seeding is not recommended as a primary establishment method.
• Bolted plants may produce enough seed to reseed the field to some extent, assuming there is not high sod competition.
• Some cultivars of forage chicory may be less palatable than others. Compared to Oasis, the cultivar used in the preliminary studies in 2007, Forage Feast appeared to be less palatable to lambs at the Athens County location in 2010, especially at certain locations in the field. Soil environment may affect palatability. Palatability or preference may be animal species dependent.

With respect to the possible effects of chicory on internal parasites in lambs, we learned:  

• Statistical analysis of the data collected on the three farms 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 two forages was similar.
• The FEC of lambs grazing both forages increased while grazing as a result of their exposure to worm larvae on the grass pasture they grazed before being moved to chicory and BMR. This was not unexpected. However, 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 observation suggests that there was an antiparasitic effect on the worms in the lambs grazing chicory, at least with regard to their egg output, and that this was 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. Discrimination among chicory plants within the paddock at the Athens County farm in 2010 may be evidence of self-medication by lambs carrying a heavy worm burden because chicory leaves collected from grazed areas had higher concentrations of sesquiterpene lactones than leaves from the ungrazed areas.
• Under the conditions used in this project where lambs grazed each forage for about two weeks, the effect of this cultivar of forage chicory (Forage Feast) on lowering fecal worm egg counts was low and probably of minimal biological importance. Longer periods of chicory consumption may be of greater benefit, but this is inadequately studied at this time. It must be noted that two of the farms had heavy weed competition in the chicory stands that reduced the overall chicory composition to 50–70%.

Laboratory analyses have shown that forage chicory cultivars vary in their proportions of three sesquiterpene lactones. Other research has recently indicated that the dominant sesquiterpene lactone in Forage Feast may have low antiparasitic activity compared to the dominant sesquiterpene lactone in other cultivars. This work suggests that other forage chicory cultivars may be better than Forage Feast for use in a small ruminant parasite control program. NCR SARE project reports are available at northcentral.sare.org/project-reports.

Summary

The planting and subsequent grazing of forage chicory is not an effective parasite control strategy in and of itself. However, forage chicory has potential as one tool within a multi-faceted approach to internal parasite control in small ruminants. It can provide a safe pasture capable of producing high quality forage for grazing lambs for a defined time period, and it can provide nutritious forage in midsummer when cool season grasses and legumes are less productive. Some forage chicory cultivars, such as Grasslands Puna and Oasis, may have greater antiparasitic activity against small ruminant internal parasites, and grazing lambs with heavy internal parasite infections may use forage chicory to self-medicate.

Within the scope of our study using Forage Feast, the benefits of forage chicory from a parasite management perspective may be limited. However, if a forage chicory cultivar with better persistence and greater anthelmintic potential were used and if high quality chicory forage were grazed for a longer period, the results might be more favorable. As a non-traditional forage, chicory should be used in combination with strategies that reduce the use of dewormers, guard against resistant worm selection, and minimize animal exposure to infective larvae. (See OSU Extension fact sheet VME-28-12, "Strategies for Coping with Parasite Larvae on Pastures in the Springtime in Ohio" at ohioline.osu.edu) Farmers need to carefully weigh the cost of establishing and managing forage chicory against the potential benefit that could be gained in their management system.

Made available with support from the Sustainable Agriculture Research and Education (SARE) program, which is funded by the U.S. Department of Agriculture–National Institute of Food and Agriculture (USDA–NIFA). Any opinions, findings, conclusions or recommendations expressed within this product do not necessarily reflect the view of the SARE program or the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.