by Heather Smith Thomas
Adult cattle are rarely affected by coccidiosis unless they are stressed
enough to hinder the immune system. But they pass the parasite eggs
(oocysts), in their manure, serving as a source of infection for calves--who
have not yet gained enough immunity to fight off the parasite.
The best defense against coccidiosis is to minimize stress and prevent
situations in which contamination can build up to infective levels.
Death rate can be high in calves suddenly introduced to a high level
of infection, as when warm wet weather brings to life oocysts in old
manure around feeding areas where cattle congregate.
Incubation from the time a calf ingests oocysts until showing diarrhea
is 16 days or longer. By day 18 or 19 the calf has diarrhea and there
may be blood in the feces. By day 21 there are oocysts in his manure.
If calves don't become reinfected, the disease runs its course; the
problem is reinfection in a contaminated environment, with parasites
at several stages within the calf until his immune system begins to
build resistance. If he's lost a lot of blood, he'll be anemic and
weak. Supportive treatment--fluids by tube or I.V.--may be needed.
Mild cases may have diarrhea but no blood in the manure. Subclinical
cases may have no diarrhea, just poor growth.
Preventative Management in Baby Calves
Young calves are very susceptible to coccidiosis. A ranch where hay
is fed through winter provides ideal conditions for coccidiosis in
calves if cattle are grouped in feeding areas, like around round bales.
Jan Shearer, College of Veterinary Medicine, University of Florida,
says the important thing is to control spread of coccidia in manure.
Don't feed hay on the ground; use clean bedding; manage cattle in
ways to prevent contamination of pastures; and minimize stress on
calves. He suggests creep feeding Deccox and keeping group size small.
Often the best prevention is to cattle spread out on good pasture
or to keep changing the feeding area. Then oocysts passed in manure
are widely scattered over a large area; calves don't pick up enough
to cause massive infection. They encounter the parasite and begin
to build immunity, but don't get enough to develop disease.
Several drugs are effective if given before symptoms appear, and less
effective after a calf is already sick. In outbreaks, all calves in
the group should be treated, even if they are not all sick. ©
