2010 Annual Report
1a.Objectives (from AD-416)
Identify non-traditional plant resources and associated management methods with potential to enhance nutrition and health of small ruminants produced in central Appalachia. Specific objective 1: Identify plant resources and determine plant growth characteristics and management practices that can expand forage options. Specific objective 2: Identify plant resources and plant management strategies that can help control gastrointestinal helminths which infect small ruminants.
1b.Approach (from AD-416)
Controlled environment, field plot, and laboratory experiments will be conducted to determine growth habit, herbage yield, and chemical composition of non-traditional pasture legumes, forbs and grasses with potential for use as forage or forage supplements for small ruminants. Emphasis will be placed on plant species having physical properties or chemical constituents that disrupt the life cycle of the gastrointestinal nematode, Haemonchus contortus or provide immune system support for the ruminant. Non-traditional plant species used in these studies include condensed tannin-containing legumes, American potato bean, purslane, artemisia, and chicory. Condensed tannin-containing forage species will be evaluated for economic potential for hay production under central Appalachian growing conditions using criteria of yield, forage quality, and stand persistence. Native Appalachian plant species that have the potential to provide sufficient yield and bioactive constituents for small ruminants will be identified. The effect of plant species, management, and season on antioxidant capacity of traditional and non-traditional forage species will be measured using samples from multi-year field studies. The influence of edaphic and solar conditions on physical and chemical properties of plant resources will be determined using plants grown with and without mineral deficiencies, with varying levels of UV light, or with natural radiation attenuation. Potential adverse effects of non-traditional plant resources on rumen metabolism and potential alterations in bioactivity by rumen microbial activity will be assessed using in vitro rumen fermentation assays. Anthelmintic activity of plant materials and isolated constituents will be determined using in vitro and in vivo parasite assays. The effect of plant morphology, sward density, and canopy height on hatching and migration of parasite larvae will be evaluated to determine how physical characteristics of pastures can be manipulated to disrupt the parasite life cycle.
Collection of data related to bioactive nontraditional legumes with potential anthelmintic activity continues at high and low altitude sites in West Virginia and Pennsylvania. Tannin concentrations in herbage are being quantified. Investigations of effects of ultraviolet light on tanniferous forages are underway under controlled environments. Field studies of purslane and American potato bean, conducted by Mountain State University (SCA 58-1932-7-767) have been concluded, and final determinations of forage quality and antiquality characteristics are underway. These plants have proven to be unsatisfactory for intended applications, and research efforts have been redirected toward selection and breeding of a forage chicory cultivar with enhanced anthelmintic activity. Relationships between nutrient limitations during plant growth and antioxidant capacity and condensed tannin concentration of forage have been investigated using birdsfoot trefoil and lespedeza grown in sand culture with macronutrient deficiencies. The antioxidant capacity of alfalfa, orchardgrass, chicory, and brassica samples from multi-year field plot studies has been quantified. Artemisia annua plants that have high concentrations of artemisinic acid and dihydroartemisinic acid have been selected because these compounds have exhibited anthelmintic activity against the gastrointestinal parasite Haemonchus contortus in laboratory assays. In collaboration with Virginia Tech parasitologists (SCA 58-1932-5-534), anthelmintic effects of crude alcoholic extracts and individual constituents of A. annua and extracts of other medicinal and tannin-containing plants are being evaluated using a screening system based on the nematode Caenorhabditis elegans. Other collaborative studies have confirmed that an orange oil emulsion administered to H. contortus-infected sheep effectively reduces fecal worm egg numbers and the worm burden. Laboratory parasitological assays conducted with chicory extracts have revealed that sesquiterpene lactones differ in their ability to inhibit H. contortus larval motility and suppress hatching of H. contortus eggs. Bulk sesquiterpene lactone extracts have been prepared from chicory herbage and are being tested in a gerbil model system at Virginia Tech to investigate differential effects of sesquiterpene lactones on worm burdens. A technique for quantifying third stage larvae of H. contortus on pasture plants has been developed and submitted for patent consideration. The method is being used to examine physical and chemical disruption of the life cycle of the parasite. Substantial progress has been made in developing a chromatographic procedure for quantification of cichorin. A rumen in vitro fermentation experiment using various plants and plant extracts was completed to identify shifts in rumen bacterial, protozoal, archeal and fungal populations. This project will provide plant materials and associated management strategies to expand forage options and H. contortus control strategies for small ruminants in humid, temperate climates.
Anthelmintic potential of chicory forage is influenced by sesquiterpene lactone composition. Forage chicory is promoted for use in sheep and goat pastures to control gastrointestinal parasites like the barber pole worm. Although anthelmintic activity of chicory herbage has been attributed to natural compounds called sesquiterpene lactones, the anthelmintic capacity of individual sesquiterpene lactones has not been defined. Using a laboratory assay, ARS researchers at Beaver, West Virginia, showed that one of the sesquiterpene lactones was much less effective than another in inhibiting hatching of barber pole worm eggs. Thus, chicory plants with a high concentration of the more effective compound would be preferable in small ruminant pastures. This information is valuable for selecting among available cultivars for grazing applications and for developing a new chicory cultivar with improved anthelmintic potential. This decision support tool will help ensure long-term economic viability for sheep and goat producers and availability of small ruminant meat products for consumers.
Orange oils have potential for controlling barber pole worms in sheep. Controlling barber pole worms (Haemonchus contortus) is a major problem for sheep and goat producers because this gastrointestinal parasite has developed resistance to commercial dewormers. Collaborative studies conducted by scientists at the ARS lab in Beaver, West Virginia, and the Virginia-Maryland College of Veterinary Medicine at Virginia Tech showed that orange-peel oils administered to sheep infected with barber pole worms reduced the number of parasite eggs excreted in the feces by 90% and the number of worms in the gastrointestinal tract by 50%. Thus, orange oils have promise as a natural dewormer. This information is valuable for developing both an alternative dewormer for small ruminants and a compatible parasite control option for organic livestock production systems.
Meat goats will eat chicory containing beneficial anthelmintic compounds. Control of gastrointestinal worms is one of the most serious problems facing producers in the rapidly growing meat goat industry. Forage chicory contains compounds that may help goats tolerate worms, but the bitter taste of the forage has reduced intake in other livestock species. Scientists at the ARS lab in Beaver, WV, determined that goats could detect bitterness differences among chicory forages, but this did not reduce their willingness to eat it. Therefore, chicory with greater amounts of beneficial compounds can be fed to goats in order to provide an alternative to ineffective commercial dewormers.
5.Significant Activities that Support Special Target Populations
Scientists have participated in activities targeting small farms and socially disadvantaged/limited resource/historically under-served producers in Appalachia: .
1)participation at the American Forage and Grassland Council annual meeting;.
2)collaboration on a SARE grant awarded to Ohio State University Extension personnel for evaluation of the use of non-traditional forages for gastrointestinal parasite control in small ruminants; and.
3)education of small ruminant extension agents and producers in the management and use of traditional and non-traditional forages for improved nutrition and health of sheep and goats at a Southwest Pennsylvania Sheep and Goat Workshop.
Cassida, K.A., Foster, J.G., Turner, K.E. 2010. Forage characteristics affecting meat goat preferences for forage chicory cultivars. Agronomy Journal. 102:1109-1117.
Ferreira, J.F., Luthria, D.L. 2010. DRYING AFFECTS ARTEMISININ, DIHYDROARTEMISINIC ACID, ARTEMISINIC ACID, AND THE ANTIOXIDANT CAPACITY OF ARTEMISIA ANNUA L. LEAVES. Journal of Agricultural and Food Chemistry. 58:1691-1698.
Squires, J.M., Foster, J.G., Lindsay, D.S., Daudell, D., Zajac, A.M. 2010. Efficacy of an orange oil emulsion as an anthelmintic against Haemonchus contortus in gerbils (Meriones unguiculatus) and in sheep (Ovis aries). Veterinary Parasitology. 172(1-2):95-99.