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.
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.