Non-traditional Forages in a Managed Grazing System for Control of Gastrointestinal Parasites in Sheep

View the project final report

• 2009 annual report
• 2010 annual report

Commodities

• Animals: goats, sheep

Practices

• Animal Production: feed/forage, parasite control, grazing management, preventive practices, grazing - rotational, therapeutics
• Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research, workshop
• Pest Management: integrated pest management, prevention
• Production Systems: holistic management
• Sustainable Communities: sustainability measures

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.

Introduction:

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.