There are three major activities that you can do to make a major difference in your
Cull the animals that are producing the majority of the parasite eggs.
Breed and select animals that don't have as much problems with parasites.
Reducing the parasite eggs in a pasture by 80%
If all of your animals produced the same amount of parasite eggs in their pellets
and you had 100 animals, you would have to get rid of 80 animals in order to reduce
the potential parasite eggs in your pastures. That would be dramatic. However, researchers
indicated that only 20% of your animals are producing 80% of the parasite eggs in
your pasture. If you can identify those animals that are more likely to be producing
the majority of the eggs, you can make a major difference in improving the health
of your herd.
One of the first things we have started to identify the animals causing the most
problems is to have a monthly evaluation of our entire herd. Once a month, each animal
has their condition checked and recorded. (see monthly management). Also, any sickness
is recorded on the animal's individual chart. Animals that have had bottle jaw and
had a difficult time getting over it are identified. Animals that constantly have
pale eyelids indicating being anemic are identified. These are some of the animals
that make up the 20% causing 80% of the parasite eggs in your pasture and the sooner
they are culled, the sooner the parasite eggs in your pasture will be reduced.
Animal Resistance, Resilience or Immunity to Parasites
During our monthly management check, we also find certain animals that always have
better color in their eyelids, better body/coat condition and don't need to be de-wormed
as often. Many times we will see that a doe with good eyelid color may also have
kids with the same.
Some goats seem to have the genetics to be much more resistant to parasites than
other goats and are better able to survive parasite levels without showing any of
the symptoms other goats have. Other goats may be dying with the same level of parasites
that does not seem to bother the animal with more resistance to the parasites.
We believe it is critical for breeders to identify these goats with the genetic resistance
when selecting their breeding herd. A herd with these types of genetics will make
a major difference in a breeder’s life and their business profitability.
An animal’s age and stage of growth play a big part in how likely they will be affected
by parasites. The older an animal becomes, the more they have been exposed to parasites
and the more they may have become resistant to them.
Resistance (immune) – an animal’s ability to resist the effect of parasites
Resilience – an animal’s ability to withstand the effect of parasites
Genetics affect an animal's ability to resist infection, as well as withstand infection.
Resistance is defined as the animal's ability to resist parasite infection. It is
measured by fecal egg counts (FEC) and is 20 to 30 percent heritable. Resilience
is defined as the animal's ability to withstand infection. It is measured by blood
hematocrit or packed cell volume (PCV). It is less heritable than resistance. This
can be generally measured by checking the color of the eyelids.
When the parasite attaches to the lining of the stomach, the goats’ major defense
mechanism against that is the immune system. When infectious agents enter the body,
the immune system reacts through a series of activities that mobilize various components
(antibodies, killer cells, etc) that then attack and kill the invaders. These components
act on the parasites in the lining of the stomach. How strong the immune response
is depends on several factors.
The immune system has to mature with age; therefore, young animals are relatively
susceptible to infection and become more resistant with age.
Nutrition and/or stress can alter a goats immune competence. Under poor nutrition
and/or stressful conditions, the immune system loses some effectiveness and can not
respond adequately. Therefore, no matter what the age of the animal, the effect of
the parasites will become worse.
Adult animals have developed stronger immunity and harbor lower infection levels.
The immunity or resistance to parasites is often penalized at times of nutrient scarcity,
and the belief is that this is because scarce nutrient allocation is prioritized
to growth and/or reproductive . Indeed, an increased supply of protein, from various
protein sources reduces the level of round worms in both growing and doe kidding
Nutrition in fighting Parasites
The effects of parasites can be influenced by the nutritional status of the goat.
It is well known that well-fed animals can better withstand parasite infections than
animals on an inadequate diet. It is also true that parasites interfere with the
ability of the host to utilize nutrients efficiently. Therefore, it is important
to understand this see-saw effect.
The better an animal is fed the better it is able to tolerate increasing infection
levels, but eventually a point is reached, depending on the worms and the conditions
involved, where parasites overwhelms the goats ability to function properly. The
more parasite infection, the more damage is done to the lining of the stomach which
will result in reduced absorption of nutrients, thus making the host utilize more
stored body reserves.
Proteins are the building blocks of the goat’s immune system so as less protein
is available, the more the goat’s immune function is compromised Protein and minerals,
as well as energy, are important in resisting the effects of the round worm because
new red blood cells must be generated to replace those lost to the parasites..
Nutrition in early pregnancy increase fat stores and has been shown to increase the
immune response to parasites. Does receiving increased protein levels during late
gestation are better able to mount an immune response to parasites.