Presentation on theme: "ANSC 420: Critical thinking in Animal Science"— Presentation transcript:
1 ANSC 420: Critical thinking in Animal Science Susan Schoenian Sheep and Goat Specialist Western Maryland Research & Education Center University of Maryland Cooperative Extension –
2 Critical thinking is learning to think for yourself and to develop your own independent opinions, backed by sound reasoning and support.Critical thinking is the process of evaluating what other people say or write to determine whether to believe their statements.
3 Critical thinkers gather information from all senses, verbal and/or written expressions, reflection, observation, experience, and reasoning.. . . to form a solid judgment that reconciles scientific evidence with common sense.
4 (Internal) parasite control in small ruminants Lecture/Discussion topic(Internal) parasite control in small ruminants
5 Small ruminants Ruminant Small Even-toed hoofed animal Cud-chewing 4 compartment stomachBovidae (hollow horns) familyCaprinea sub familyOvis aries (54 chromosomes)Capra hircus (60 chromosomesSmallsheep, goat, cervids (deer)
6 Sheep and goats Multi-purpose animals Meat Dairy Fiber Vegetation controlResearch and biomedicalHobbyYouth projects (4-H, FFA)Pets
7 Sheep vs. goats More similarities than differences. Same problems, same opportunitiesMostly the same diseases and health issues.
8 Sheep and goats in Maryland 2002 Ag Census: 22,702 sheep (655 farms) and 9,601 goats (702 farms)Some large farmsfemalesOver 500Largest farm has 1,600 sheep for bleedingOnly 4 certified dairy goat farms; no sheep dairiesA lot of small fiber flocksMostly small farmsAverage flock size is less than 30A lot of niche marketing of lamb and wool products.Some commercial productionMostly hobby, 4-H, tax advantage
9 Internal parasite Parasite An animal or plant that lives in or on a host (another animal or plant) and obtains nourishment from the host without benefiting or killing the host.Internal parasiteAn organism which lives in an animal and derives its nutriment from the host animal often causing death or damage to the host. This term is usually reserved for worms.
10 Internal parasites (worms) Primary health problem affecting small ruminants in warm, moist climates like Maryland.Sheep are goats are more susceptible to the effects of internal parasites than most other livestock.
11 Why more susceptible? Close grazing Goats forced to graze Small fecal pelletsGraze close to feces and each other.Slower to develop immunityIncomplete immunity (goats)Temporary relaxing of immunity at lambing/kidding.Lack of veterinary expertiseLack of FDA-approved drugsWorms have become resistant to most dewormers (drugs).Main parasite is a blood sucker and killer!
12 Lack of veterinary expertise Many veterinarians will not work with farm livestock.Many veterinarians lack technical and/or practical knowledge of sheep and goat health issues.The cost of treating a sheep or goat often exceeds its value.There is often a disconnect between veterinarians and producers.Most sheep and goat producers learn to do their own veterinary work.They are often in violation of extra-label drug laws (they have no choice!).
13 Lack of FDA-approved drugs Three families (chemistries) of anthelmintics.BenzimidazolesNicotinic agonistsMacrolytic lactones1-2 drugs in each family are FDA-approved for use in sheep.Valbazen®Levamisol ®Ivermectin ® and Cydectin ®Only two drugs are FDA-approved for use in goats.Safeguard ®Rumatel ®U.S. Organic standards do not permit deworming of meat animals.There is growing public scrutiny regarding the use of drugs in food animal production.Therapeutic Medical use
14 Lack of anthelmintic efficacy Overuse (therapeutic) and sometimes misuse (e.g. pour-ons and injectables, underdosing) has lead to the emergence of drug-resistant worms in all three anthelmintic classes.Highest levels of resistance have been reported in the benzimidazoles and ivermectins.Drug resistance is determined using a fecal egg count reduction test or DrenchRite® larval assay test.Resistance is permanent (levamisole ?).
16 Non-chemical “dewormers” Nematode-trapping fungusCopper oxide wire particlesCondensed tannins (Sericea lespedeza)Natural dewormers are currently be evaluated by researchers:Garlic juicePumpkin seedsWormwoodDiatomaceous earthOregano oil (coccidiosis)A vaccine is under development.
17 The internal parasites of sheep and goats Stomach wormsTapewormsLungwormsLiver flukesCoccidiaMeningeal worm
18 The “other” parasites These parasites tend to cause less problems than the others TapewormsTend to be non-pathogenicNo beneficial effect of treatmentLungwormsDifficult to diagnoseLiver flukeNot thought to be a problem in MarylandMeningeal wormParasite of the white tail deer (sheep and goats are abnormal hosts)Requires intermediate host (snail, slug)Causes neurological damage.
19 Coccidia Eimeria sp. Single-cell protozoa Species-specific Permanently damages lining of the small intestines.
20 Coccidia life cycle2 to 3 weeks oxygen, moisture, warmth
21 Diagnosing coccidiaAffects mostly young lambs and kids, 1 to 6 months of age.Diarrhea is the most common symptom. It often contains blood or mucous.Other symptoms: loss of appetite, rough hair coat, poor growth, ill thrift, loss of body condition, dehydration.Fecal egg flotation*
22 Treating coccidiosis Amprolium (Corid)* Sulfa drugs* Must individually treat each animal.Must treat each animal in pen.Cannot reverse permanent damage.* Not FDA-approved for goats
23 Prevention of coccidiosis Some level of “infection” is normal.Most fecal tests will be “positive” for coccidia eggs.Young animals require low level of exposure to develop immunity.Prevention starts with good sanitation and management.Clean pensFeed and water that is free from fecal matterAvoid overstocking
24 Prevention of coccidiosis Coccidiostats aid in the prevention of coccidiosis and can be put in the feed, mineral, or drinking water.Monensin (Rumensin®1)Lasalocid (Bovatec®2)Decoquinate (Deccox®12)Oregano oil (experimental)Amprolium (Corid)Feed/mineralDrinking water1 FDA-approved for goats 2 FDA-approved for sheep
25 Coccidiostats Inhibit growth but do not kill coccidia Reduce coccidia in the environmentStart 30 days before lambing/kiddingContinue through weaningInclude in lamb and kid rationsHave many other beneficial effectsFeed efficiency, rate-of-gain, aid in prevention of toxoplasmosis and bloatCan be toxic to equines
26 Gastro-intestinal worms The barber pole worm and its relatives Haemonchus contortus Barber pole wormOstertagia circumcincta Medium or small brown stomach wormTrichostrongylus Bankrupt or hair worm
27 Barber Pole Worm Symptoms Is difficult to control because . . Rough hair coatSymptomsPale mucous membranesEdema (bottle jaw)Not diarrhea (scours)Sudden DEATHFecal egg flotation (?)Is difficult to control because . .Short, direct life cycleProlific egg producerCan go into “hypobiotic” (arrested) state during winter to survive.Can survive on pasture for a long time.Weight loss, unthriftyBottle jawPale membranes
28 Stomach worm life cycle 2-3 weeksEggs require warmth (60°F) and humidity to hatch to first stage larvae.
29 Infective larvae on pasture (if no treatment) Lambing RiseSpring Rise
30 Fecal egg counts Ewes Lambs Lambing Weaning F M A M J J A S O N D J F SpringSummerFallWinter
31 Integrated Parasite Management (IPM) Goal is not to create parasite-free animals. It is normal for sheep and goats to have parasites. Goal is to prevent clinical disease and production losses.
32 Parasite control begins with good management and common sense Good sanitationFeeders which prevent wastage and contamination.Clean water, free from fecal matter.Not overstocking pens and pastures.Isolation and deworming of new animals.The primary cause of internal parasitism is overstocking.
33 Use “clean or safe” pastures What is a safe pasture?New pasturePasture that has been renovated with tillageA pasture that has not been grazed by sheep or goats for the past 6 to 12 months.Pasture grazed by horses and/or cattle for the past 6 to 12 months.Pasture in which a hay or silage crop has been removed.Pasture that has been rotated with row crops.Burnt pastureSeverely overgrazed pasture????Cleaner, safer pastures are a more realistic goal for most producers.
34 Graze multiple species Sheep and goats share the same internal parasites, but they are different from the parasites that affect cattle and horses.Producers who graze multiple species of livestock report fewer parasite problems.Cattle and horses“vacuum” sheep/goat pastures.There are other benefits to mixed species grazing, such as complimentary grazing habits.
35 Pasture Rest and Rotation Pasture rotation is a recommended strategy for controlling internal parasites because it allows the use of safe or safer pastures.BUT, intensive rotational grazing generally does not help to reduce parasitism unless rest periods are long enough.In a rotational grazing system, ideally, sheep/goats should not be returned to the same pasture for 2 to 3 months.Due to increased stocking rates, management intensive grazing may increase internal parasite problems in sheep and goats.
36 Alternative foragesLivestock that browse have fewer parasite problems.Livestock grazing tall-growing forages will have less parasite problems.80% of parasites live in the first 2 inches of the vegetation.Grazing some high-tannin forages may reduce the effects of parasitism.
37 Forage ChicorySericea LespedezaBirdsfoot TrefoilChicory, birdsfoot trefoil, and Sericea Lespedeza have been shown to reduce fecal egg counts and/or larval development.
38 Nutritional Management Animals on a high plane of nutrition and in better body condition are better able to withstand worm burdens.Nutrition in early pregnancy (fat stores) can affect the immune response to internal parasites.Sheep receiving higher levels of protein prior to lambing have lower fecal egg counts.Supplementing lambs with protein has been shown to reduce fecal egg counts.
39 “Zero” grazingSheep/goats raised in confinement or dry lot (zero grazing) have fewer stomach worm problems.Sheep/goats put in confinement or dry lot do not usually get re-infected with stomach worms.Coccidiosis could still be a problem.
40 Genetics and worms Two important traits: resistance and resilience Ability of host to limit infectionAssessed by fecal egg counts (FEC)ResilienceAbility of host to withstand challenge and/or infection, and thus maintain health and productivity.Assessed by blood hematocrit/packed cell volume (PCV) and eye anemia score.Moderately heritable – percent
41 “Resistant” Breeds Some sheep and goat breeds are more resistant to worms. Gulf Coast NativeHair sheepBarbados BlackbellySt. CroixKatahdinRoyal White (?)Select populations of other breeds(?)NOTTraditional wooled breedsDorperGoatsSpanish/BrushMyotonic/TennesseeKikoPygmy?Savannah????NOTBoer goatsDairy goatsAngora goats
42 “Resistant” Individuals Parasite resistance varies between individual animals of the same breed type.20-30 percent of flock shed most of the parasite eggs.Focusing deworming on susceptible animals will significantly reduce pasture contamination.Culling worm-susceptible animals will increase flock resistance and reduce pasture contamination.
43 Heritability of FEC and PCV FEC (resistance)PCV (resilience)Ewes0.310.15Lambs0.100.392004, Vanimisetti, Andrew, Zazac, NotterSelection for parasite resistance is possible and will not adversely affect growth of lambs and fertility of ewes.
44 Comparison of Genetic and Non-genetic Control Strategies StrategyReduction in FEC’sGenetic Selection69%Protein supplementation35%Strategic deworming28%Experimental vaccine0%Australia, 2002Monitor sheep, run in the plots after the end of the experiment had lower FEC’s when run in the plots previously grazed by supplemented sheep (35%) or selected sheep (46%).The largest and most persistent effect on FEC’s and worm contamination of pasture was achieved by genetic selection.
45 Maximize the effect of a single treatment Give proper dose;do not underdose.Dose orally (all formulations)Put dewormer in back of mouth behind tongue.Restrict feed hours before administering a benzimidazole or ivermectin or administer two treatments hours apart.Use higher dose for goats than listed on label. Goats usually require 1.5-2X the sheep/cattle dose. (Consult with veterinarian for proper dose for goats).Use two different drugs.
46 Slowing Down Drug Resistance DO NOT overuse drugs, especially Levamisole and Moxidectin.DO NOT introduce resistant worms to your farmIsolate new animals and deworm them aggressivelyDO NOT underdoseWeigh animals or dose for heaviest animals in group.DO NOT rotate dewormers after each treatmentRotate dewormers annuallyRotate among drug familiesUse specific dewormers for specific situations.DO NOT treat everybodyLeave some animals untreated
47 “Refugia” – in refuge from the drug What is refugia?Worms not exposed to drug;therefore still susceptible to treatment.The goalIncrease the population of susceptible worms.How?Selective treatment – leave some animals untreated.After deworming, do not move animals to a clean pasture.You do not have to deworm every animal.
48 How We Select for Drug resistance Parents Next Generation Drug TreatmentSusceptibleResistantResistant
51 Fecal Egg Counting Qualitative Analysis Quantitative Analysis Shows presence or absence of eggsIdentify egg typesShows general trendsQuantitative AnalysisShows specific number of eggs per gram of feces (epg)Use known quantity of feces and flotation solution.
52 What do fecal egg counts tell you? Potential pasture contaminationFecal egg counts are not mathematically correlated to worm numbers or the severity of parasitic disease.Monitor and maintain low egg counts; deworm when appropriate to keep contamination of pasture low.Determine the efficacy of anthelmintic treatment by comparing paired samples from the same animals (treatment and control group).
53 Next Wednesday’s farm visit Small meat goat farm in Clarksburg (typical operation for Maryland)Evaluate overall health management, with specific attention to the control of internal parasites (worms and coccidia).Reduce morbidity and mortalityMinimize costMinimize use of drugs
54 Pasture and grazing management SanitationPasture and grazing managementManagementInternal parasitesWormsCoccidiaEquipment and facilitiesGenetics and selectionFeeding and nutrition