Presentation for 2020 Texas Sheep & Goat Expo

1. PASTURE MANAGEMENT TO
CONTROL INTERNAL PARASITES
SUSAN SCHOENIAN
Sheep & Goat Specialist
University of Maryland
Extension
sschoen@umd.edu
wormx.info
sheepandgoat.com

2. CURRENT SITUATION
Internal parasites are the
primary health problem
affecting small ruminants
in warm, moist climates
and/or times of warmth
and moisture.
In the past, internal
parasite control relied
mostly on treatments with
dewormers.
This approach eventually
led to high levels of drug
resistance.
Integrated approaches
which rely less on drugs are
now needed.

3. DEWORMERS
Proper use of dewormers
Targeted selective treatment
Combination treatments
Refugia
Testing for resistance
MANAGEMENT OPTIONS
Pasture and grazing management
Nutritional management
Genetic selection
Management / husbandry practices

4. Weather
dependen
L3
L4
L
3
A
A = adult
L = larvae
https://www.agric.wa.gov.au/livestock-parasites/barbers-pole-
L
2
L1
Host
Animal
Pastur
e
Manure

5. Factor Time or conditions
Number of eggs deposited daily
Up to 10,000 per day for barber pole worm
Much less for other worm species
Maximum time worm eggs can live
waiting for suitable hatching conditions
5 days for barber pole worm
Longer for other worms
Minimum time for egg to develop
into infective third stage larvae (L3)
3-4 days (4 to 10 days)
Conditions required for significant numbers of
worm eggs to hatch and become infective
larvae.
Daily maximum >64.4°F (50-96°F)
Moisture 0.4-0.6 inches rainfall
Minimum time for L3 to develop into adult
worms
“prepatent period”
18 days for most sheep roundworms
Adult worm life span 4-6 months
Time for 90% of larvae to die
Weeks to months
Temperature dependent
Longer for non-barber pole worms
IT’S MOSTLY A NUMBER’S GAME!

6. REFUGIAWORMS NOT EXPOSED TO THE DEWORMERS
Internal parasite control is a conflict between
controlling worms and slowing dewormer
resistance
Refugia is now the primary strategy for slowing
dewormer resistance.
Leave a portion (10-20%) of the flock/herd
untreated.
Dilute resistant worms on a pasture by putting
untreated animals on pasture previously grazed by
treated animals or by returning treated animals to
same pasture for a week or so before moving them
to a clean pasture.

7. PASTURE MANAGEMENT
BASICS
Pasture is the
reservoir and vector
of transmission.

8. ROTATIONAL GRAZING
A well-designed
rotational grazing
program can help to
reduce worm burdens.

9. SHORT DURATION
GRAZING
GOAL IS TO PREVENT “AUTO-INFECTION.”
Though weather
dependent, worm
eggs can develop into
infective 3rd stage
larvae (L3) as quickly
as 3-4 days.
It takes longer when
weather is cooler
and/or drier.
If animals are moved
every 3-4 days (or
less), they will not
ingest infective larvae
unless they are
returned to the same
paddock too soon.

10. LONG PASTURE REST
PERIODS
GOAL IS TO CREATE LOW-RISK
PADDOCKS.
Once the larvae lose their metabolic
reserves, they die. In hot weather,
reserves are quickly used up. Cool, moist
conditions support survival of larvae.
Rest pastures long enough for most
larvae to die.
Parasite larvae will die more quickly if
the pasture is mowed or after a hay crop
is removed.
Tillage buries any worm eggs and cleans
the pasture up.
Max Temp Time for 90% to
die
Cold < 59°F 4 months
Warm About 72°F 3 months
Hot About 95°F 1.5 months
Very
hot
Over 104°F 1-2 weeks

11. MINIMUM GRAZING
HEIGHTS
TO MINIMIZE INGESTION OF L3
Parasite larvae can migrate laterally
and vertically in films of moisture.
Most larvae migrate no more than 4
to 6 inches up the canopy.
Most larvae (~80%) are found in the
first 2 inches of vegetation.
Do not overstock or overgraze.
Graze above 4 to 6 inches to
minimize ingestion of infective
worm larvae.
Let animals browse, esp. goats.
Plant taller growing forages.

12. ALTERNATIVE FORAGES
Forages containing condensed tannins have been shown to
have inhibitory effects on barber pole worm infections:
sericea lespedeza, birdsfoot trefoil, and chicory.
Annual crops provide clean, nutritious forage for grazing.
Legumes and forbs improve the nutrition of pastures.
Pasture composition can affect movement of infective larvae.
Browse provides clean, nutritious forage for grazing.

13. MULTI-SPECIES
GRAZING
TO REDUCE PASTURE
CONTAMINATION
Parasites are mostly host-
specific.
Sheep/goats are generally not
infected by the same parasites as
cattle and horses. The exception
is young calves and H. contortus.
Can co-graze, alternate
pastures, or use a leader-
follower system.
There are numerous other
benefits to multi-species
grazing.

14. INTERNAL PARASITISM WHEN IT’S DRY
Internal parasites are generally not a
problem in dry climates (<25 in. annual
rainfall) or during a drought, as
environmental conditions aren’t
conducive to egg hatching and larval
development.
During dry weather, larvae are retained
in the fecal pellets. The larvae don’t
need rain to survive. When it rains, the
larvae are released from the pellets.
Lower
risk
Higher
risk

15. INTERNAL PARASITISM
WHEN IT’S DRY
Livestock can still get infected in a
drought because they graze closer to
the ground to get the last vegetation
(where the larvae are) and in green areas
(hot spots).
When/once it rains, there can be a huge
increase in infectivity (disease several
weeks later), as the larvae are release
from the egg.
During a drought, there are more
refugia in the animal than on pasture.

16. ZERO GRAZING
STRATEGIC USE OF CONFINEMENT
(BARN OR DRY LOT)
Worm parasites do not spread
in barns or dry lot.
Coccidia can be more of a
problem.
Remove severely parasitized
animals from pasture for
recovery
(e.g. FAMACHA© 5).
When other control measures
are not working, put animals
in dry lot.
Raise more susceptible
animals in dry lot, e.g.
weanlings.

17. BIOWORMA®
BioWorma® is a worm-
killing fungus.
(Duddingtonia flagrans)
It kills roundworm larvae
in the manure of animals
It prevents reinfection of
pastures with infective
worm larvae (L3).
It is feed-through
product with no effect in
animal (wormy animals
still need treated).
Natural-Biological control
Environmentally-friendly
Not organic (yet)

18. FEEDING BIOWORMA®
Feed daily to livestock
during periods of peak
worm transmission,
>40°F.
Feed to the most
susceptible animals,
usually peri-parturient
females and young,
weaned lambs/kids

19. TWO BIOWORMA® PRODUCTS
BIOWORMA®
Feed additive that contains 34%
fungus.
Dosage is 0.1 oz per 100 lbs.
Needs to be mixed into a batch
of feed
Can only be purchased by
veterinarians and EPA-certified
feed manufacturers and mixers.
 Premier 1 Supplies is now able to
sell because they have
veterinarians on staff.
LIVAMOL® + BIOWORMA®
Nutritional supplement (20% CP)
that contains 2.2% fungus.
Dosage is 1.6 oz per 100 lbs.
Read-to-use product
Mix or top dress in feed
Anyone can purchase
www.bioworma.c

20. COST OF
BIOWORMA®
+ LABOR TO FEED IT
Reducing the cost and labor
Feed BioWorma® instead of Livamol®
Research questions
Could BioWorma® be fed for two weeks out
of the month and give similar results?
Could BioWorma® be fed every other day and
give similar results.?
Would feeding BioWorma® to periparturient
females control parasites sufficiently in
weaned lambs/kids?
Could BioWorma® be put in a mineral product
and give similar results.
Would you need to feed less BioWorma® over
time, as your pastures became cleaner?

21. SUSAN SCHOENIAN
SHEEP & GOAT SPECIALIST
UNIVERSITY OF MARYLAND EXTENSION
SSCHOEN@UMD.EDU | WORMX.INFO |
SHEEPANDGOAT.COM
Thank you. Questions? Comments?