16 CUMBRIA FARMER May 2009
Lambs and calves at riskRob's jeans are
an inspiration
THE appearance of Rob Lister in
last month's Cumbria Farmer wear-
ing holey jeans covered in mud
after handling a calf caused some
chuckles among his friends and
neighbours.
One of his neighbours was
inspired to pen these few lines
about Rob from Oughterside Mill,
near Aspatria.
When Cumbria Farmer spoke to
Rob, he was on his way to Blackpool
with Cumbria Young Farmers and
reportedly wearing his smartest
jeans!
Every day on British farms,
children like Robert are forced to
work in conditions like this!
He has to wear leaking Wellington
boots, old rugby jerseys and pants
with no knees!
He's not even allowed time off to go to
the toilet and has to do it in his pants.
Please help by sending all you
can afford to Help the Children,
Oughterside branch.
BY REBECCA MEARNS
Veterinary Laboratories Agency
C
occidiosis is a common
cause of diarrhoea,
especially in young
lambs and calves. It is
caused by a protozoan parasite
called eimeria,of which there
are many species.
Most species do not cause dam-
age, but some are pathogenic and
damage the gut-lining cells, usu-
ally in the lower small intestine
and large intestine.
They are host-specific � ie eime-
ria species that infect cattle can-
not infect sheep and vice versa.
The basic life-cycle is the same
for all species. Oocysts (eggs) are
shed in the faeces and these
develop to the infective stage on
the pasture which is then eaten.
These sporozoites `hatch' from
the oocyst and penetrate the gut-
lining cells. Here they multiply
and burst out, releasing further
life-cycle stages that infect more
gut cells leading to more damage.
After several cycles, oocysts
form which are passed in the fae-
ces. The length of the life-cycle
varies with individual species
but is usually two to three weeks.
In sheep, coccidiosis occurs in
lambs aged three to eight weeks,
and there are two species that
cause harm � eimeria crandallis
and eimeria ovinoidalis.
Adult ewes shed oocysts at low
levels, contaminating the pas-
ture. Lambs with good maternal-
ly derived immunity are protect-
ed in the early days. During this
time, any oocysts they eat will
stimulate their immunity with-
out causing disease.
However, lambs that have had
inadequate colostrum will not be
protected. They pass millions of
oocysts and are the main source
of infection for other lambs.
If large numbers of oocysts are
eaten, the damage can cause diar-
rhoea and even death due to
dehydration and kidney failure.
Management of lambs aims to
allow immunity to develop
through exposure to the parasite
without clinical disease develop-
ing. As the life-cycle takes two to
three weeks, lambs can be safely
grazed on pasture for two weeks
then moved to allow the next batch
of lambs on to the same pasture.
By the age of eight weeks, most
lambs have developed immunity.
To diagnose coccidiosis, faecal
samples are examined to count
the oocysts.
The disease can also be diag-
nosed by examining scrapes from
intestinal mucosa of animals sub-
mitted for post-mortem examina-
tion. This is useful in lambs
where few oocysts have been
found on faecal examination. Dis-
ease can occur before the life-
cycle is complete and, in this
case, examination of a faecal sam-
ple will not identify any oocysts.
Diarrhoea can also continue
when shedding has stopped and
even after treatment as the dam-
aged gut needs time to recover.
Disease is often worse in lambs
that are stressed for other reasons.
Where coccidiosis is con-
firmed, the whole group should
be treated with an anti-coccidial
drug. Seek advice from your vet.
In cattle, there are three
species that cause harm � eime-
ria bovis and eimeria zuernii,
which cause disease in calves
three to 12 weeks of age.
Affected calves typically have
dark scour and may strain some-
times, leading to rectal prolapse.
Another species, eimeria alaba-
mensis, can cause diarrhoea in
older calves and occasionally
adult cattle at grass.
This is usually seen in the first
grazing season and has been
called `turn-out coccidiosis'.
Eimeria alabamensis can over-
winter for at least two years on
pasture. Avoid grazing young-
stock on pasture used for first
grazers in the previous year if
this form of coccidiosis has been
confirmed on the farm. Older cat-
tle are a safer option as they will
`hoover' up the oocysts.
Confirming diarrhoea caused
by eimeria alabamensis can be a
challenge as shedding starts ear-
lier than in typical cases of coc-
cidiosis and multiple samples at
five-day intervals may be needed
to reach a diagnosis.
Coccidiosis can also affect
goats and South American
camelids. There are three
pathogenic species of eimeria in
goats (eimeria caprina, eimeria
christenseni and eimeria
ninakohlyakinovae) and at least
one in camelids (eimeria macu-
saniensis). The coccidia affecting
alpacas and llamas require an
additional method to count them
as they are heavier than other
coccidial parasites.
Alpacas: Coccidiosis can also affect South American camelids
Large numbers
of oocysts can
result in death
Rob Lister: In those jeans
LivestockHealth

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