Parasite control for dairy cattle

Question 1

important dairy ectoparasites

Answer 1

Chorioptes
Lice

Question 2

important dairy endoparasites

Answer 2

• Cryptosporidium
• Eimeria spp.
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• Hypoderma spp. ?
• Dictyocaulus viviparus ?
  > these are problems depending on location and management (eg. pasture)
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  GI nematodes > Parasitic gastroenteritis ?
• Ostertagia
• Trichostrongylus
• Cooperia
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• question marks = only an issue on pasture

Question 3

Macrocyclic lactones for cattle
- what do we use? milk withdrawls?

Answer 3

1. invermectin
   - injection: 60d
   - pour-on: 60d
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2. Doramectin
   - Injection:60d
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3. Eprinomectin
   - Pour-on: 0 days
   - Injection: Do not use

Question 4

Drugs with a zero milk withdrawal

Answer 4

1. Eprinomectin (Eprinex) Pour-on
2. Permethrin (Boss/Vetolice) Pour-On
3. Cyfluthrin (CyLence) Pour-on

Question 5

chorioptic mange - when we see it

Answer 5

• common in Ontario – adult cattle indoors
• late winter/early spring
• impact on production ?
• lesions generally disappear after turnout

Question 6

lice - when we see them

Answer 6

• relatively common in Ontario ?
• low #s on adult cattle – subclinical ?
• high numbers on young livestock
• indoors
• heaviest infestation - winter/early spring
• self cure in spring ?

Question 7

when do we do preventative treatment for external parasites

Answer 7

fall - reduce burdens in the fall, so we dont get significant burdens in the winter

Question 8

Cryptosporidium parvum
- when do we see it?
- control?
- prevention?

Answer 8

• very common infection
• typically 1-4 weeks of age
• should be controlled by attention to environmental hygiene and colostrum feeding
• preventive= halofuginone lactate (Halocur)

Question 9

Eimeria spp. (coccidia)
- when we see it?
- prevention

Answer 9

• common infection?
• disease at > 2.5weeks of age
• calves commonly maintainedon coccidiostat (lasalocid, monensin, decoquinate) (toltrazuril = single PO)

Question 10

Hypoderma spp. (warbles)
- where do we see it? who?
- when to treat?

Answer 10

• absent from southern Ontario?
• more common in younger cattle
• fall treatment before December = preventive

Question 11

Dictyocaulus viviparus
- when is it a problem? control?

Answer 11

• uncommon in southern Ontario
• more common in younger cattle + at pasture
• disease in second half of grazing season
• should be controlled by GIN preventive program

Question 12

Development of GINs in environment
- most important?
- stages? temp?
- when to we need prevention?

Answer 12

• Primary GIN in Ontario = Ostertagia
• L1, 2, 3 in feces; after that, off feces
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• Resilient stages: eggs + L3
  > typically some will survive winter
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  Development at 5-32C
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  prevention required if cows go on pasture
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• Indoors or outdoors?
• Cattle in tie stall herds more likely to go to pasture compared to cattle in free stall herds:
• tie stalls: ~80% pasture
• free stalls: < 5% pasture - dry cows ?
• First season at pasture (whatever age) animals are immunologically naïve to GINs

Question 13

Development of GINs in cattle
- where so ostertagia and cooperia live?
- PPP
- development of immunity
- seasonal development of parasite?
- egg count on pasture significance?

Answer 13

Abomasum: Ostertagia Small intestine: Cooperia
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Most significant facts:
1. Prepatent periods ~ 3 weeks
2. Development of immunity: a) rapid – Dictyocaulus (one grazing season required) b) slow - Ostertagia (multiple grazing seasons required)
3. Arrested development in fall in cattle.
4. Some Ostertagia over-winter on pasture in Ontario.
5. Poor relationship between fecal egg count and impact on production.

Question 14

GIN infections in first grazing season if no deworming
- timing

Answer 14

• if you keep pasture free of cows until end of June, all parasites will die out
  > but we usually turn out cattle in ~April
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Question 15

Parasitic gastroenteritis in first grazing season
- disease presentations

Answer 15

Clinical (= type 1 ostertagiosis):
 high morbidity ?
 diarrhea, weight loss, anorexia, etc
 moderate/high fecal GIN egg counts
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Subclinical + production loss:
 reduced growth rates
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Subclinical + no production loss

Question 16

Targeted control program
- objective and appoach

Answer 16

• Objective: Minimize patency in first half of grazing season
• Prevents accumulation of large #s L3 on pasture
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  Approach:
  1. Preventive grazing systems:
• low stocking density
• pasture rotation
  2. Targeted chemoprophylaxis
  3. Monitor efficacy of regime

Question 17

Timing of treatments ?
Duration of drug’s protection against Ostertagia vs PPP

Answer 17

(a) Ostertagia prepatent period = 3 weeks
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(b) Duration of drug’s protection against Ostertagia:
* SafeGuard Premix (fenbendazole) = 0 days * Ivomec Pour-On (ivermectin) = 14 days * Eprinex Pour-On (eprinomectin) = 28 days

Question 18

targeted (minimum) intervals for ostertagia treatment
> based on length of residual activity

Answer 18

Non-persistent anthelmintics:
- first treatment at 3 weeks, second 3 weeks later
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Ivomec Pour-On (2 weeks activity):
- first treatment at 3 weeks, second 5 weeks later
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Eprinex Pour-On (4 weeks activity):
- first treatment at 3 weeks, second 7 weeks later
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Ideally, increase time before treatments by 1+ weeks

Question 19

Second grazing season for ostertagia
- treatment protocol

Answer 19

• same protocol as first year ?
• if targeted regime was used in first year there probably is the need to be as aggressive

Question 20

can you justify deworming adult cattle?

Answer 20

• commonly harbor low numbers of Ostertagia
• impact of >/= 1 treatment on milk production:
  > 87 studies = -2.33 to +3.16 kg/day
  > median = +0.63 kg/day (Gross et al. 1999)
• number of calf treatments = main influence of response in cows (Bisset et al. 1987)
• Ontario–common practice to treat once/year in fall