Bloat Common Cattle Diseases

122 Beef Breeder MANUAL

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. 123 Cold Winter Climates 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. 124 Beef Breeder MANUAL 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