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Goats and their parasites have evolved over a
long period of time and under more primitive conditions the level of
parasitism in animals would probably be limited by their tendency to
roam over greater areas. Now, breeders often collect up the animals
and restrict them to small pastures where the numbers of parasite
larvae can build up to dramatic numbers leading to frequent drug
treatments leading to resistance
The more animals you have in one pasture, the
closer your goats graze to the ground and the more likely they will
ingest larvae. The question we always have asked to us is "how many
goats can I run in my pasture?". There is no general, correct answer
of that question. Some people will quote that a breeder can run 6-8
goats where one cow can run. That may or may not be correct but if
it is, it is only correct on what may be available to eat in the
pasture. A cow generally does not have problems consuming parasite
larvae while eating close to the ground but that is exactly where
the goats get infected. There is nothing I have found on the
internet that will tell a breeder how to identify the number of
goats they can run on their pastures.
I know that we have too many goats for the
acreage we have fenced for them. Here is how we are trying to
estimate how many goats per acre without increasing the risk of
parasite infection.
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What is the smallest pasture your goats
will be rotated through and how long will they need to be in
that smallest pasture? We have four small pastures that are
fenced for our does/kids and they range from 1.5-4 acres each.
So our smallest pasture is 1.5 acres. From reading the info on
the life cycle of the round worm, I know that the larvae in a
pasture can survive any where between 1-3 months in hot weather
and 6-10 months in cool/cold weather. So we are likely to
schedule our herd to move into the smallest pasture after 1-3
months of the hottest/driest weather. That would be the best
chance that the pasture has the least number of larvae still
alive in it.
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What are the typical number of animals
you will have at the time you would move them to the smallest
pasture? We keep our bucks separate so we are looking at the
number of does/kids we would have towards September. If all
animals are removed from the small pasture by the end of June,
that would give the pasture 3 months of hot weather before we
put animals back in it. We may have 30-35 breeding does. They
would have generally had 75 kids between November and
April. Hopefully at least half of those kids will be gone before
September so that gives us around 30 kids plus the 30-35 does
for a total of 60-70 animals on 1.5 acres. That is way too many.
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How long can you run the animals on your
smallest pasture? This depends upon what browse is in the
pasture, how much and the height of the browse the goats eat.
When you put your animals in a pasture, look to see what percent
of the pasture they are covering while they are browsing at any
one point of time. In our smallest pasture, the herd looks like
it is covering about ten percent of the pasture at any point of
time. That means, if the goats ate everything they could, within
on day, in that
one spot, in 10 days, they would eat everything in the pasture
and would have dropped pellets across nearly 100% of the
pasture. If you have lots of browse for them to eat, then that
can be extended BUT the life cycle of the parasite worm is
around 21 days and shorter if the environment is right for
hatching the eggs. The drier the weather during this time, the
longer I may be able to stretch the grazing in this pasture but
any good moisture during this time starts the hatching life
cycle and starts the infestation of larvae in the pasture.
Since I am putting animals in this small pasture in September,
we will still be having some hot weather but the temperature
will start dropping soon and that means it will be a longer time
before I can bring animals back into the pasture. The fewer
animals you have in your pastures, the fewer larvae they will be
picking up.
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Consider all of the pastures and
determine if you can safely rotate your herd through them for a
year considering the the size of the pasture, the weather
environment and the potential life expectancy of the larvae
during all seasons. With our having four small pastures and the
number of animals in the herd, we have determined we have too
many animals for the available pasture space and we will have to
reduce our herd significantly and/or take some other steps to
help manage the parasite problems.
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References:
- Article 1- Purdue University - Managing Internal Parasitism in Sheep
and Goats
- Article 2 -Alabama A&M
University Cooperative Extension System - BARBER POLE WORM
INFESTATION IN GOATS
- Article 3
-Virginia-Maryland
Regional College of Veterinary Medicine
Virginia Tech, -
Controlling Goat Parasites
- Article 4
-Division of Parasitology and
Tropical Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
– Effects of Mowing
- Article 5 -
EU study -
Parasites and Tannins
- Article 6 - University of Maryland - Integrated Parasite Management (IPM)
in Small Ruminants
- Article 7 - Louisiana State University – Internal and
External Parasites in Goats
- Article 8 -SAC Research – Nutrition and Parasites
- Article 9 -Terry Hutchens Extension Associate for Goat
Production UK & KSU Terry Hutchens Extension Associate for Goat Production
UK & KSU - Gastro-Intestinal Parasite Survival Kit For Goats
- Article 10
-Animal
Nutrition and Health Team SAC, Edinburgh - Opportunities to reduce
gastrointestinal nematode parasitism through nutrition
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Article
11 -National Sustainable
Agriculture Information
-
Managing
Internal Parasites in Sheep and Goats
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Article
12 -NSW Department of Primary
Industries, Armidale1 NSW Department of Primary Industries, Armidale1 NSW
Department of Primary Industries, Armidale, Australia – Turning the Worm
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Article 13 - Texas A&M
University - Understanding Internal Parasites
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Article 14 -
Helminth Parasites in the New
Zealand Meat & Wool Pastoral Industries : A Review of Current Issues
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