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4.5.7. Bloat
Bloat is another nutrition disease that can have a signiicant economic impact on cattle grazing pastures
and forages. It tends to be a seasonal condition that is usually caused by the rapid consumption of lush
legume pasture species, and some forages and grasses containing high levels of soluble proteins in spring,
summer and autumn. Bloat is caused by an increase in the gas pressure
within the rumen as these feeds are fermented. The gas cannot be belched up normally and death results from
the pressure; causing heart and lung failure. The gas is often trapped in the form of a stable foam.
Bloat is often triggered by cattle gorging themselves with legume rich pasture. Hungry cattle should not be
allowed access to these areas. Feeding out grass hay a few hours before the cattle are moved into a new
paddock will reduce their appetite. If faced with a choice of grazing fresh young forages or mature forages, the
cattle should be introduced into more mature pastures. An increase in the height of legumes will generally
decrease the risk of bloat. Legumes in lower are safer to graze than the less mature stages.
Cattle will learn to moderate their pasture intake to control the extent of bloating and discomfort. This
occurs over several weeks. Older cattle are better at adapting their grazing behaviour than younger animals.
Figure 4.41. Cattle displaying signs of bloat, with the abdomen distended outwards and upwards on the left side. Source: University of Nebraska, Lincoln.
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Cattle with bloat may display the following signs: • No longer grazing
• A reluctance to move • Distended left abdomen Fig. 4.41
• Appear distressed - vocalise, eyes bulging • Strain to urinate and defecate
• Rapid breathing - mouth may be open with tongue protruding; staggering.
The animal will go down in advanced cases. Death is rapid at this stage, and is due to the swollen rumen
compressing the lungs; interfering with breathing and obstructing blood low.
Treatment Earlymild cases of bloat can be treated orally with an
anti-bloat preparation. After dosing, keep the animal moving to encourage the preparation to mix with the
frothy rumen contents. Moderately afected stock that are bloated and starting
to show signs of distress need veterinary attention. A stomach tube can be used to relieve the gas build-up,
and anti-foaming agents can be delivered directly into the rumen. Moving the animal around after treatment
is important. In severe cases, bloated and distressed animals will
need veterinary attention and rapid relief. This is usually done by inserting a wide-bore trochar and cannula into
the rumen high on the left lank where the swelling is greatest. After gas and froth is released, an anti-bloat
preparation may be poured through the cannula into the rumen to help break down remaining frothfoam
dose according to label instructions. In emergency situations, vegetable oil 250 to 500mL or parain oil
100 to 200mL has traditionally been used. Prevention via Management
Fast growing, legume dominant pastures should be avoided until the pasture matures further and bloat risk
declines. Mature pastures with less than 30 legume content pose little risk of bloat. Dew on the grass is
also believed to increase the incidence of bloat. Cattle selectively graze succulent grasses and legumes which
makes assessing the risk of a pasture diicult, hence pasture management should not be solely relied on to
control bloat. Increasing ibre intake will reduce bloating. Feeding
grass hay daily can help to reduce the intake of pasture with a high bloat risk. However, some animals will eat
pasture in preference to the hay. Prevention via Medication
There are several labour saving methods for the administration of anti-foaming agents to beef cattle.
However none are 100 efective. They are usually used in conjunction with other management strategies
to minimise losses from bloat. • Sustained Release Anti-bloat Capsules - Each
capsule is approximately 150mm in length and is administered as a large plastic pellet down the throat
and into the rumen. They provide a continuous supply of ingredient for 80 to 100 days and must be
given one week prior to the cattle being introduced onto ‘bloaty’ pasture. A second capsule is required
if the bloat season extends beyond 100 days or if bloating occurs in your area during other times of
the year. The capsules have been found to reduce bloat deaths by about 80
• Bloat Blocks - Bloat blocks or licks place minimal demands on management and are popular. Several
types are on the market and contain a speciic detergent. Bloat control relies on each animal
consuming an adequate daily dose of the block. Cattle can be encouraged to use the blocks by
placing them close to stock camps and watering points. Alternative control methods are required for
those animals which do not use the blocks • Water Trough Treatments - Medication of the cattle
through their water supply is another alternative. The addition of chemical makes the water less palatable
so all other water sources must be fenced of. The daily dose that each animal receives depends on the
amount of water consumed and the concentration of the chemical in the water. The water consumption
of individuals can vary substantially depending on the water content of the pasture and the weather.
The chemical in the trough will be diluted when fresh water is released from the ball cock. This
problem can be overcome by shutting of the reilling mechanism and replenishing the trough
with chemical and water daily. Otherwise a metering device which releases chemical with the water will
be required.
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THE SUCCESS OF BEEF CATTLE HERDS is dependent on the producer being able to implement a successful
breeding program for the herd. This extends from the conceptual process of establishing
breeding objectives for the herd and determining the genetic pathway to produce cattle that satisfy target
markets, through to the very practical outcome of producing healthy calves on the ground. Understanding
these processes and principles will underpin the long term success of beef cattle genetics imported from
overseas countries, and Australia in particular.
To assist with the planning and running of the range of activities that are required to be successfully
implemented, an annual Calendar of Operations has been developed that is based on the combined
experience of commercially successful beef cattle production systems in countries with cold winter climates
such as Canada, northern USA, Russia and Kazakhstan TECHNICAL NOTE 1 - Calendar of Operations for Beef
Cattle Production in Cold Climates. These activities are outlined in the following sections of this Manual.
5.1. Developing a Breeding Objective