This PowerPoint presentation is the second in a four-part webinar series on worms (in sheep and goats). The presentation covers integrated parasite management (IPM): host immunity, pasture and grazing management, nutrition, management, and genetics. The presentation is by Susan Schoenian, University of Maryland Extension Sheep & Goat Specialist.

1. Boer goat grazing chicory II. Integrated parasite management (IPM) Controlling internal parasites without or before you need to use anthelmintics: host immunity, grazing and pasture management, nutrition, management, and genetics.

2. Key points of parasite control The goal is not to eradicate worms, but to reduce their adverse effects in practical and economical ways. The interaction between parasites, the environment, animals, and management decisions is complex. Drug resistance is a serious challenge to effective parasite control.

3. Parasite infection in sheep and goats Parasite infection is normal in sheep and goats. The number of worms found in individual animals varies, with essentially all animals having some worms (and coccidia). It is rare to find animals uninfected.

4. Parasite infection in sheep and goats The nematode population in a flock is over dispersed. A majority of the nematodes are in a minority of the animals. The 80-20 rule: 20 percent of the animals shed 80 percent of the worm eggs.

5. Parasite infection in sheep and goats The risk and severity of parasite infection varies by . . . Season Year (weather) Geographic location (climate) Farm Production system Animal

6. Integrated parasite management (IPM) Whole farm or systems approach to managing internal parasitism. Applying best management practices to minimize the effects of parasites and the need for deworming. Holistic worm management. There is no one way or “magical” recipe for controlling parasites.

7. Integrated parasite management Host immunity Pasture and grazing management Nutrition Management Genetics Anthelmintic treatment

8. Host immunity Sheep and goats have several defense mechanisms for dealing with internal parasites: Immune exclusion Self-cure Immunity Innate Acquired

9. IMMUNE EXCLUSION SELF-CURE PHENOMENON Ingested larvae fail to establish in heavily infected animals. Adult nematodes are spontaneously expelled when there is a massive larval invasion over a very short exposure period. Usually observed after a heavy rain. Why does it occur (?) Increase in abomasal pH IgE mediated hypersensitivity

10. Immunity (2 kinds) The ability to resist a particular disease. St. Croix lambs ACQUIRED Immunity that is not inherited. Immunity that is acquired during life. Immunity that results from exposure to the disease. INNATE (inborn, natural) Infection is limited during the initial exposure. Immunity that occurs naturally as part of an individual’s genetic make-up. Crossbred lambs

11. Immunity Develops with advancing age and parasite exposure. Not until >4 months of age, depending upon breed and nematode species. Preventative anthelmintic treatments interfere with the development of immunity. Adults are generally immune to parasites, but under stress can break down. Goats show the weakest degree of immunity of any livestock.

12. Periparturient egg riseRelaxation of immunity around the time of parturition Lasts for about 4 weeks May occur earlier (in pregnancy) if animals are underfed or under stress. Primary source of infection for new crop of lambs and kids. Cause (?) Hypothesis: Lactation after pregnancy Increasing prolactin levels Reduction in IgA antibodies associated with transfer of maternal antibodies in colostrum

13. “Spring” periparturient egg rise If lambing and kidding occur in the spring, it will coincide with the maturation and egg production from previously arrested worm larvae. Management strategies Deworm all females prior to parturition with an anthelmintic that is effective against hypobiotic larvae. Increase protein level of ration during late gestation. Selective deworming using FAMACHA© system and Five Point Check©.

14. Pasture and grazing managementThe “cornerstone” of effective parasite control. Clean or safe pastures Pasture rest/rotation Stocking rates Alternative forages Browsing Plant height Plant morphology Plant moisture Mixed species grazing

15. Clean or safe pastureA pasture that is FREE from parasites. Newly planted dwarf pearl millet A pasture that has never grazed by sheep or goats. A pasture that is grazed once per year by sheep and/or goats. A pasture that has not been grazed by sheep or goats for 6 to 12 months. Pasture that has been grazed by cattle or horses for past 6 to 12 months. Pasture in which a hay or silage crop has been removed. A pasture that has been renovated with tillage. A pasture that has been rotated with row crops. Burnt pasture. Annual pastures. Cleaner, safer pastures are usually a more practical option.

16. Pasture rest/rotationThe primary method for creating safer (less contaminated) pastures. Parasite infection is driven by stocking rates and duration of grazing periods.Overgrazing -> parasitism The higher the stocking rate, the more the pasture gets infected and the more likely livestock are to ingest infective worm larvae. The longer the grazing period, the more the pasture gets infected and the more likely livestock are to ingest infective parasite larvae.

17. Rotational grazing There is no “one-size fits all” pasture rotation schedule. There are many variables to manage: Climate Season Rainfall Number of paddocks Size of paddocks Number of livestock Susceptibility of livestock Forage type and quality Supplemental feed There is often a trade-off between parasite control and good pasture management.

18. General recommendations It takes approximately 60 days for a highly contaminated pasture to become lowly contaminated with worm larvae. “Take half, leave half” Don’t graze below 4 inches (10 cm).

19. Plant height It is estimated that 80 percent of infective worm larvae are found in the first 2 to 3 inches of the ground surface. Do not graze pastures below 4 inches. Overgrazing is one of the primary causes of internal parasitism in small ruminants.

20. Alternative forages Forages containing condensed tannins and sesquiterpene lactones. Sericea lespedeza Chicory Birdsfoot trefoil Artemisia spp. Chicory How do they work (?) – reduce egg hatch and development of larvae.

21. Sericea lespedezaLespedezacuneata(high tannin variety) Warm season legume that grows in acidic soils with low fertility and is tolerant of drought. Goats readily eat.Sheep will eat. For control of barber pole worm only. Effective when consumed as Fresh forage Loose or ground hay Pelleted supplement Images from scsrpc.org

22. Browsing Goats that are allowed to browse (their natural grazing behavior) have fewer parasite problems. Browse should be managed to provide continuous nutrition for goats. Sheep will also browse.

23. Plant morphology There are lower numbers of larvae on non-grass plants, e.g. legumes, forbs. Non-grass plants reduce parasite survival on pasture or reduce larval migration up plant. Management strategies Include legumes in pasture mixes (e.g. 30%). Plant alternative forages. Red clover

25. NutritionThere is an interaction between parasites and nutrition. Livestock are far more capable of coping with parasites if their nutritional needs are being met. Animals on low protein diets are more susceptible to infection because they produce less IgA.

26. Nutritional control of parasites Improved protein nutrition. Increased body protein reserves. Feed periparturient females protein at 130% of requirements. Provide supplemental protein to grazing livestock, especially at-risk animals and during periods of poor forage quality. Manage pastures so that they are grazed in a vegetative state.

27. Management options Sanitation Biosecurity Zero grazing Timing of lambing and kidding Weaning age

29. BiosecurityDon’t introduce drug-resistant worms to your farm Quarantine new animals for 30 days In a pen away from rest of flock/herd. No fence line contact Deworm with anthelmintics from 2-3 drug chemistries, e.g. Cydectin® + levamisole Valbazen® + Ivomec® + levamisole

30. Zero grazingconfinement, dry lot, feed lot, elevated floors Can maintain animals relatively “worm-free” under zero grazing conditions. Coccidiosis is still a risk. Primary source of infection (and re-infection) is removed: grazing. Pens should be kept dry. Feeders and waterers need to be kept clean. No feeding on pen floor or ground. Dairy goats in China

33. Genetic aspects of parasite control Some animals mount a significant response to internal parasite infection, while others do not. Some animals do not mount a noticeable response to internal parasite infection, but they suffer no obvious loss of production. There is significant within and between breed variation in parasite resistance and resilience.

34. Two genetic traits RESISTANCE Ability to prevent infection from establishing. Quantified by fecal egg counts. Moderately heritable h2 ranges from 0.22 to 0.63 Avg. h2 is 0.25 RESILIENCE (tolerance) Ability to limit damage caused by parasites Quantified by clinical signs: packed cell volume (barber pole worm), dag scores, etc. Less heritable than resistance, ~ 0.1

35. Resistance and resilienceBoth traits are equally important! There is a cost to parasite resistance as resources are directed away from production traits. Resilient animals may still carry significant parasite loads and be a source of contamination to the pasture and other animals. Correlation between two traits No correlation between worm resistance and resilience in New Zealand studies. Positive correlation between two traits in Australian work. Low (positive) or no correlation in Western Maryland Pasture-Based Meat Goat Performance Test.

37. Barbados Blackbelly

38. KatahdinGulf Coast Native Kiko Spanish Myotonic Naturally-selected resistant breeds of sheep and goats have developedresistance over a much longer term(decades and perhaps centuries) than short-term (few years)genetically-selected resistant lines within breed. St. Croix sheep

39. Breeding for worm resistanceWithin breed selection RESISTANCE RESILIENCE Cull animals with high fecal egg counts. Don’t select replacements with high fecal egg counts. Don’t use rams or bucks with high egg fecal counts. Include fecal egg counts in a selection index. Select animals based on a minimum standard for parasite resistance. Use EPD’s to select for parasite resistance. Use gene markers to select for parasite resistance. Cull animals that require frequent deworming. Don’t select replacements that require frequent deworming. Don’t use a ram or buck that requires frequent deworming. Make sure you are comparing animals in the same contemporary group (i.e. similar breed, age, and management).

40. Small Ruminant Program Thank you for your attention. Any questions? Susan Schoeniansschoen@umd.eduwww.sheepandgoat.com Next webinar: Diagnostic tools (May 19)