Basics of Sheep Health Care

Transcription

1 Basics of Sheep Health Care

2 NAHMS Sheep Producer Surveys Veterinary consultation as a diagnostic service: 40-53% 46% of surveyed producers consulted a veterinarian in 2000 NAHMS 1996, 2001

3 Veterinary services & sheep production Sheep practice: smallest fraction (4%) of total US food animal veterinary service market Wise, JAVMA, 1987

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5 What are the veterinarian s goals for serving western range flocks? To assist the producer in increasing the number of lambs born, the uniformity of the lamb crop, and the number that survive to weaning.

6 How can this be accomplished? Ram fertility testing Brucella ovis eradication Ultrasonographic confirmation of pregnancy Neonatal lamb managment

7 Late summer / early fall Last spring s lambs have been sold, except for replacement ewe lambs 1. Ewe cull; prepare ewes for upcoming breeding season 2. Ram test; prepare rams for same.

8 Prebreeding Ewe Cull Body Condition Score (target: 2-3) Low BCS (< 2 out of 5): Poor nutrition Broken mouth / Gummer Parasites Footrot Other Diseases

9 Bag Check Status of udder will influence ewe s ability to raise twins, triplets Mastitis: Bacterial: Staphylococcus Viral: Ovine progressive pneumonia virus (OPP)

10 Those that pass BCS, teeth, and bag check: Deworm (anthelmintic medicine) Vaccinate

11 What vaccines do sheep need? Enterotoxemia and tetanus ALL sheep Clostridium perfringens type C Clostridium perfringens type D Clostridium tetani Can give now or pre-lambing

12 Prebreeding vaccinations vs. infectious causes of abortion Vibrio (Campylobacter fetus fetus) bacterin Enzootic abortion of ewes (Chlamydophila abortus) bacterin 2 doses: 1 prebreeding, second 2-4 weeks later When to use? Owner preference Contact w/ other flocks during pregnancy Flock history of abortion storms New introductions into flock - Keep away from pregnant flock!

13 Cats and Toxoplasmosis Parasite shed in cat feces Esp. young cats Abortion, stillbirth, weak lambs

14 Ensuring Ram Fertility Shear Shade Sand Salt and water Semen test Serologic test

15 Watch crude protein level in feed! Ulcerative posthitis ( pizzle rot ): Excessive protein in ram feed

16 Pathogenesis High protein feeds (greater than 16 % crude protein) induce high [urea] in the urine Bacteria (Corynebacterium renale) proliferates on sheath, cleaves urea to ammonia

17 Chemical dermatitis results, other bacteria invade secondarily Pain and reluctance to breed Can scar down and limit capacity to breed

18 Treatment Critical step: Remove high protein diet Systemic antibiotic therapy and/or topical therapy

19 Ram Breeding Soundness Examination (BSE) Ram fertility has a profound impact on flock economic performance: size and uniformity of lamb crop; reduced ram #s; lambing labor. Demonstrable economic results

20 ~ 5 month gestation Conception Lambing Breeding season

21 FERTILE RAMS Breeding season

22 SUBFERTILE & INFERTILE RAMS Breeding season

23 The S s of Late Summer Ram Management Shear Shade and Sand Salt and water Semen test Serology (Brucella ovis) Sperm that they use on a given day were made ~ days ago

24 Ram Breeding Soundness Exam (BSE) RBSE is a systematic, objective assessment of potential for a ram to impregnate a defined number of ewes through natural service. Goal: Identify the duds, keep the studs. ID and remove subfertile rams. Fertility influenced by events prior to breeding season

25 Ram Breeding Soundness Examination

26 Brucella ovis infection Venereal disease: Can spread to involve most or all of the rams in a flock reduced lamb crop, nonuniform lamb crop from repeat breedings abortion (rare) more rams purchased to cover ewes

27 What is the cost of B. ovis infection? 15-30% reduction in lamb crop Bulgin, 1990 Loss incurred through reduced lamb crop: $487 per 100 ewes - fewer lambs than what could have been born Loss incurred through extended lambing season: $182 per 100 ewes - These losses often go unseen Kimberling, 1988

28 Producer Survey Kansas State University B. ovis ELISA performed on 58 rams Origin: Results: 13 Kansas flocks 5 positive on ELISA 4 suspect on ELISA, all 4 suspects retested and found to be positive 9/58 = 15.5% of tested rams were positive 0 of 13 owners thought they had the disease beforehand Van Metre & Kennedy, unpublished data, 1998

29 What is the cost of B. ovis infection? Loss incurred through reduced lamb crop: $487 per 100 ewes Loss incurred through non-uniform lamb crop: $182 per 100 ewes - These losses often go unseen Kimberling, 1988

30 Detection of B. ovis infection in a ram: How is it done? 1. Feel the epididymis 14% of 408 infected rams had palpable abnormalities of the epididymis Kimberling, 1988

31 2. Attempt to culture the bacteria from ram semen? Expensive and inaccurate these bacteria are difficult to culture in the lab Clumped white cells Sperm cells (dark) 3. Examine semen for white cells? White cells appear intermittently in semen samples, particularly if the infection is longstanding

32 4. Serologic testing: ELISA test (best method for finding infected rams) Takes 2-4 weeks from the time of infection until antibodies appear Gall et al, 2003

33 CSU Ram Testing Study, rams tested for B. ovis 241 (9.9%) tested positive Of those positive for B. ovis: ~ 50% would have otherwise passed their breeding soundness exam their sperm sample can appear normal!

34 Comparison of lamb crops in two flocks: Economic justification One with rams that passed BSE and were B. ovis seronegative vs. One with random source, untested rams Kimberling & Schweitzer, 1989

35 $12 per ewe (1989 dollars) In flock w / tested rams: Economic advantage of $12 per ewe for larger lamb crop alone Besides lamb crop: -Reduced expenditure on additional ram power -Shorter lambing season -More lambs born early in the lambing season -Increased size and uniformity of lamb crop

36 Other aspects of the ram test:

37 How do you detect infection? granuloma Approximately 1 in 7 infected rams will have abnormal epididymides or testes

38 Serologic testing: Detection of antibodies to B. ovis in an infected ram s blood, using a test called an ELISA Takes 2+ weeks from the time of infection until antibodies appear Almost all infected rams develop detectable antibodies within 6 weeks of exposure Serologic test all incoming rams Part of a routine breeding soundness test of rams

39 Colorado study, 1989 Comparison of lamb crops in two flocks: One with rams that passed BSE and were free from B. ovis vs. One with random source, untested rams

40 Results: It pays. Increased lamb crop in flock w / tested rams: Economic advantage of $12 / ewe Besides lamb crop: -Reduced expenditure on additional ram power -Shorter lambing season -More lambs born early in the lambing season -Increased size and uniformity of lamb crop Kimberling & Schweitzer, 1989

41 FERTILE RAMS Breeding season

42 CSU Ram Test Data, ,763 exams Satisfactory: 71% Questionable: 10.8% Unsatisfactory: 18.1%

43 Reasons for unsatisfactory / questionable classification of rams (4,252 failed exams) Reasons for failure % of failed exams Sperm morphology or motility 43.2 Physical abnormalities (including low scrotal circumference and emaciated or obese) 30.8 Inflammatory causes 20.0 (Epididymitis / WBC in semen / seropos. for B. ovis) Ulcerative posthitis (pizzle rot) 4.6 Other 1.4

44 Summary Points on Ram Testing Infertile and subfertile rams are an economic burden to the producer and may serve as a source of ovine brucellosis. Optimizing ram fertility has been demonstrated to have tangible, positive economic results. Ovine brucellosis is commonly subclinical and must be detected through serology.

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46 Ultrasound examination for pregnancy ~ 5 weeks after last ram contact

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49 Benefits of ultrasound exam 1. Serves as early indicator of infertile ram. An entire lamb crop can be missed if the ram is infertile. 2. Allows one to cull open ewes. This provides savings on winter feed costs ~$70 (1990 $US) to feed a ewe over the winter. 3. Can sell open ewe lambs. Recall that these were born the previous spring. If sold in the fall, they will sell as lamb. If you keep these until the spring, they will be classified as mutton.

50 4. Allows for sorting of ewes according to stage of pregnancy or by # of fetuses - fetal counting easiest at day of gestation (40-80 if you re really good) Can group into early and late lambers >1 fetus: fed more grain to limit risk of pregnancy toxemia

51 Winter / Spring First lambs may arrive at the end of this month +/- Clostridium perfringens C&D, tetanus toxoids to boost colostral titers, if not given prebreeding. colostrum supply

52 Lamb Mortality Benchmarks NAHMS Sheep 1996: Preweaning Mortality, all regions: 9.4% (out of lambs born alive) NAHMS Sheep 2001: Preweaning Mortality, all regions: 10.0% Willingham et al, 1986: Preweaning mortality, TX study: 13.6%

53 Primary Causes of Mortality WB Saunders Co, 1990.

54 Lamb losses: Most occur early in life

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57 Lambing Clip, dip, and strip Clip umbilical cord to length of 2 Dip umbilicus in iodine or novalsan Strip out udder of ewe - removes plug, allows for detection of mastitis

58 Colostrum first milk Contains antibodies vs. infectious agents Critical for lamb survival

59 Tube feeding warmed colostrum: I.U. oxytocin IM to ewe, wait 3 min., milk out Milk into urine cup, collect in larger cup away from ewe Triplets / dystocia lambs: may want to jump start 60 ml colostrum via tube to each Repeat 1-2 times in first 24 hours

60 Summary Points Ultrasonographic confirmation of pregnancy prevents $ loss from overwinter feeding of barren ewes Most lamb losses occur in the first week of life Ensuring colostrum intake is vital to lamb health

61 Questions?