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Over recent years there’s been an
alarming increase in the incidence of
liver fluke. This has coincided with a
greater geographic distribution
beyond the traditional at-risk high
rainfall areas.
The main signs of liver fluke infection are a
reduced growth rate, a gradual depression of
milk yield, and stock that are generally not
thriving. Sheep are particularly susceptible to
fluke and infection can cause serious illness
and death. However in cattle fluke is often
overlooked because the signs are very subtle
and clinical disease is rare. But an absence
of fluke symptoms and a lack of farm history
of fluke is no reason to leave fluke risks
unmonitored. Many farmers see the need
to treat for fluke infection in sheep where
symptoms can be more graphic, yet fail to
recognise the production loss in cattle. A fluke
control strategy is still recommended for both
cattle and sheep.
Liver fluke life cycle
'Liver Fluke' (Fasciola hepatica) is a flat leaf-like
parasite (Figure 2) that can grow up to 3.5cm
in length. It is a parasite found in the liver of
grazing animals. Eggs from adult female fluke
pass in the dung to contaminate pasture.
When conditions are suitable (i.e.damp and
warm) - the eggs develop and hatch to form
mobile larvae that seek out mud snails to
complete their life cycle.
The presence of the amphibious mud snails
determines the distribution of fluke. So the
highest risk grazing are wet areas and rutted
pools of water.
LIVER FLUKE IN CATTLE
WORKING
TOGETHER
FOR A HEALTHIER FUTURE...
13
LIVESTOCK MATTERS
Veterinary Surgeon
Neil Laing
XLVets Practice
Clyde Veterinary Group
in cattle
NE I L LAING,
CLYDE VETER INARY GROUP
Fluke infection has been recognised for generations, but evolving
problems in cattle demand we look afresh at how liver fluke might
be undermining herd performance.
Liver fluke
Consequences of fluke
infection in cattle:
l
A low grade infection of just 100 fluke
has been shown to reduce milk yield
by 400 litres/cow/lactation.
l
Fluke has a detrimental effect on butterfat.
Research has shown untreated animals
can produce 10 per cent less milk solids.
l
Heavily pregnant dry cows in poor
body condition can experience a
fluke-associated nutritional challenge in
late pregnancy.
l
Calf birth rates on fluke-infected cows
can be up to 10 per cent lower.
Youngstock will also experience poorer
growth rates giving reduced efficiency
for the rearing of replacement heifers.
l
Reduced feed conversion and
depressed appetite; dry matter intakes
can reduce by as much as 11 per cent.
This nutritional stress depresses fertility
and compromises the cow's immune
status. In essence fluke infection will
reduce lifetime performance.
l
Fluke infection can also precipitate
other infectious disease such as the
Clostridial infection Black disease or
it can compound outbreaks of
Salmonella.
Figure 1: Life cycle of the liver fluke