Parasite control programs for beef cattle Flashcards

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1
Q

How are beef herds managed differently from dairy herds?

A
  • All cows should calve within 60 days – degree of confinement (time of year) varies
  • Calves are the cows’ responsibility
  • Raised on pasture
  • Calves are weaned at approximately 200 days
  • Cows (and post-weaned calves) are managed as groups – allows parasite control to be TARGETED
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2
Q

Important ectoparasites of beef cattle in Ontario ?

A

Lice
Hornflies

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3
Q

Important endoparasites of beef cattle in Ontario ?

A
  • Cryptosporidium ?
  • Eimeria spp.
  • Hypoderma spp. ?
  • Dictyocaulus viviparus ?
    <><>
    Parasitic gastroenteritis:
  • Ostertagia
  • Trichostrongylus
  • Cooperia
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4
Q

Macrocyclic lactones for cattle? meat withdrawl?

A
  1. Ivermectin
    - Injection: 35d
    - Pour-On: 49d
    <><>
  2. Doramectin
    - Injection: 40d
    <><>
  3. Eprinomectin
    - Injection: 120d
    - Pour-On: 0d
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5
Q

Other non-macrocyclic lactone anthelmintics available for use in beef cattle (only GINs):
- meat withdrawl?

A

Fenbendazole - Premix
- meat withdrawl 13d

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6
Q

Lice in beef cattle
- when we see them?
- prevention timing and drugs?

A
  • common in Ontario
  • more common on beef than dairy cattle
  • high numbers on young livestock
  • fall treatment = preventive
  • some macrocyclic lactone pour-ons sold with a 28-day co-mingling guarantee
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7
Q

Hornflies (Haematobia irritans)
- when we see them?
- where?
- consequences
- prevention methods

A
  • worst in July/August
  • withers, shoulders, flank, around eyes
  • moderate infestations (>50 per side) > reduced weight gain
  • most producers use preventive measures:
  • insecticide-impregnated ear tags, backrubbers
  • insecticide spray (e.g. permethrin)
  • macrocyclic lactone pour-on (i.e. ivermectin)
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8
Q

Coccidiosis
- which ones?
- when are they an issue?

A
  • Eimeria bovis + E. zuernii = most important species
    <><>
    Most commonly an issue in:
    (a) Early born (i.e. February/March) calves in yards in ~April
    (b) Calves at pasture – late summer/fall (associated with feeding/watering areas)
    (c) Backgrounding facilities/Feedlots (typically within the first month)
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9
Q

Gastro-intestinal nematodes
- exposure timing
- immunity development
- pasture burdens
- impact?

A
  • exposure increases throughout grazing season <–> pasture intake
  • trickle infection
  • development of immunity generally quicker than dairy cattle
  • L3 burdens on pasture
    generally less than dairy
    cattle
  • subclinical impact
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10
Q

when are beef calves born and turned to pasutre?

A
  • ~75% calves born February-May (in yards)
  • turned out to pasture ~May 1
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11
Q

in calves born when will coccidia be a problem? what should we do?

A

(a) February/March calves:
* in yards with dams until ~May1
* cryptosporidiosis uncommon?
* coccidiosis can be a problem (~April)
– minimal consumption of creep feed, even if available:
> long-acting sulfa boluses or toltrazuril to group
<><>
(b) April/May calves:
* coccidios is not usually a problem

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12
Q

First year
Calves on pasture:
- when is coccidia a problem?
- possible solution?

A
  • coccidiosis can be a problem late summer/fall (typically in association with feeding/watering areas)
  • creep feed sometimes provided last few months on pasture:
  • include decoquinate or lasalocid for 6-8 weeks prior to weaning ?
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13
Q

First year
Requirement for deworming at pasture in Ontario ?

A

Requirement for deworming at pasture in Ontario ?
(a) If cows not dewormed - treat calves in July:
- ivermectin pour-on
- February/March calves appear to benefit
- not justified for May/June calves
OR
(b) Treat cows in fall with macrocyclic lactone:
> heavier calves weaned the following fall

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14
Q

First year
Calves weaned at confinement in ~October
- what parasites should we prevent at this time? how?

A

Treat with macrocyclic lactone at confinement -
Preventive for:
- lice
- gastro-intestinal nematodes (Ostertagia)
- warbles, D. viviparus
<><>
Ivermectin (e.g. Ivomec) pour-on commonly used in Ontario

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15
Q

First year +
Remain in confinement until slaughter
- what to give at backgrounding or feedlot?

A

Backgrounding
* 4-5 months
* inclusion in feed of decoquinate for first month ?
* inclusion in feed of monensin for remaining time
<><><><>
Feedlot
* inclusion in feed of decoquinate for first month ?
* inclusion in feed of monensin for remaining time
<><><><>
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* clinical coccidiosis rarely seen if coccidiostat used

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16
Q

Second year – at pasture
Replacement heifers
<>
Remember:
* All treated with macrocyclic lactone the previous fall?
<><><><>
when to treat? how?
what if not treated previous fall?

A

Second year
(a) Treat 3+ weeks after turn out
- optimal time if at pasture the previous year and treated with a macrocyclic lactone in fall
- if handling not possible:
* treat via feed (e.g. fenbendazole)
- if handling possible:
* use macrocyclic lactone (e.g. ivermectin)
<><><><>
<><><><>
(b) Treat at turn out ?
- could be justified if:
(i) not treated with macrocyclic lactone the previous fall
(ii) medicating after turnout is an issue
- must use drug with residual activity
- if use eprinomectin injectable (LongRange), ideally leave 10% untreated

17
Q

Second year
Are two treatments during the grazing season justified ?

A
  • probably not in Ontario, particularly if cows are treated in the fall
  • definitely not if eprinomectin injectable is used
  • monitor fecal egg counts 4+ weeks after anthelmintic activity has terminated ?
18
Q

Second year Replacement heifers:
* off pasture end September
* first calf the following spring
- treat how and when?

A

Treat with macrocyclic lactone when come off pasture

19
Q

Third year – at pasture
Adult cows:
- treatment

A

Treat with macrocyclic lactone in fall
- preventive for lice, warbles
- to prevent overwintering of Ostertagia in cows
> increase weaning weights of calves
<><><><>
Note: if treat cows in fall, justification for treating calves prior to housing at end of their first grazing season is questionable