Home' Target 100 : Animal Welfare Contents Animal Health
Disease prevention is a complex business for farmers. Animals like cattle and
sheep have their own diseases and are also exposed to parasites that differ
depending on which region of Australia they live in. Two key elements to
maintaining the health of cattle and sheep are vaccinations against diseases
and parasite control.
Vaccines can help prevent common livestock diseases, leading to improved
animal health and ensuring animals are able to breed and grow. In Australia,
vaccines can help prevent diseases like bovine respiratory disease, which is
caused by a combination of stress and disease-causing agents (viruses and
bacteria). Vaccination of lambs against Ovine Johne’s disease, a bacterial
disease, can reduce the number of lamb deaths by 90%. Vaccines are used
at different times in the production cycle, depending on the disease and the
vaccine. Vaccines may also be used as part of industry biosecurity programs,
to limit the spread of or help eradicate emergency animal diseases.
Parasites that affect cattle, sheep and goats include internal parasites, such
as worms, flukes and protozoa (a type of single-celled organism), and external
parasites, such as flies, ticks, lice and mites. Parasites of cattle and sheep can
be zoonoses, meaning they can infect humans also, for example the hydatid
tapeworm found in sheep and dogs.
There are a number of ways in which parasites can have a negative impact on
the health and welfare of animals. Parasites can cause blood loss, diarrhoea or
open sores on the skin. Infestation with parasites can reduce appetite, resulting
in debilitated animals that are more susceptible to other diseases. They can
also act as agents for disease transfer (much like mosquitoes transfer malaria
parasites in humans). Flies can annoy animals, causing them to reduce
grazing behaviour or, in severe fly waves, become very agitated (fly worry).
In the case of flystrike, this can even lead to death. Parasites can reduce the
growth, milk production and reproductive rates of cattle and sheep.
Parasite control initiatives include quarantine to prevent them from entering
the country in the first place. Some varieties of parasites of cattle, sheep and
goats are not found in Australia, for example screwworm fly and some types
of mites. It is important to keep these parasites out of Australia and industry
biosecurity helps ensure this.
Parasites can cross from one species to another. In research funded by
cattle and sheep farmers (Target 100 Initiative #98), Charles Sturt University
scientists are working to eradicate sheep measles, which is caused by a specific
dog tapeworm. The worms’ intermediate stage causes clear fluid-filled cysts
in muscle, which can degenerate into calcified nodules. Together with National
Red Card Fox Control Program, a community based feral animal control
program operating in Western Australia, the researchers are investigating the
role of foxes and wild dogs in spreading the tapeworm. As part of the project,
an education package is being developed for farmers for the control of sheep
1796 English physician Edward
Jenner trials a cowpox vaccine to
1881 French scientist Louis Pasteur
successfully vaccinates sheep and
cattle against the human and animal
1909 Danish scientist Wilhelm
Johannsen coins the word “gene”.
1930s CSIRO’s Arthur Turner
had developed a vaccine against
contagious bovine pleuropneumonia
in the 1930s. Australian herds
are finally free of the devastating
disease in 1973, following a national
1952 American geneticists Alfred
Hershey and Martha Chase show that
only the DNA of a virus needs to enter
a bacterium to infect it, supporting the
idea that genes are made of DNA.
1965 The British government
releases the Brambell Report, that
later leads to the development of
the five freedoms for animals under
2009 The complete sequence
of the bovine genome and a study
of global cattle genetic diversity are
published in the journal Science.
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