Animal health in beef cattle feedlots
Infectious diseases
J P Cronin, Biosecurity
DPI&F,
Toowoomba
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Footrot
This disease is seen at times in feedlot cattle, especially under wet conditions or where there are predisposing conditions such as rough gravel or stones in the feedlot. Cattle from drier environments have a lower immunity.
Clinical signs
Animals are noticeably lame, usually in one leg. Hoof swelling is usually seen.
Treatment
Treatment should be discussed with your veterinary surgeon. Affected animals should be isolated and treated as soon as they are noticed. This will have the dual benefit of a more rapid return to normal for these animals and it will help prevent the spread of footrot in the feedlot.
Antibiotic treatment under veterinary advice may be considered appropriate. Remember to record all treatment details such as eartag of the treated animal and the time of the last treatment.
Prevention
Affected animals should be isolated and treated as soon as they are noticed. This will have the dual benefit of a more rapid return to normal for these animals and it will help prevent the spread of footrot in the feedlot.
Also remove any boggy or rough areas from yards and lanes in the feedlot.
Enterotoxaemia (pulpy kidney)
Enterotoxaemia is a clostridial disease and it occurs more commonly in feedlot cattle than in range cattle. Because affected animals become bloated and die suddenly, it is often confused with feedlot bloat. Death rates in infected animals can approach 100%.
The organism causing the condition is a normal inhabitant of the bowel in ruminants, but only in small numbers. There is inevitably some contamination of feed by animal faeces and some organisms survive passage through the rumen and abomasum (true stomach) to reach the small intestines. Under certain conditions these bacteria proliferate rapidly in the intestines and produce lethal quantities of toxin. These conditions may occur when grazing lush, rapidly growing pasture and crops or with heavy grain feeding in feedlots. The undigested starch which reaches the last part of the small intestines of feedlot cattle provides a ready substrate for rapid growth of these organisms. Sudden changes in diet are likely to precipitate the disease.
Clinical signs
Signs seen in animals which survive for up to 24 hours are of a nervous type - bellowing, mania and convulsions, followed by death. Adult cattle often exhibit a severe terminal bloat. The best conditioned animals in the group are often affected.
Treatment
Treatment is unlikely to be effective because of the rapid and irreversible action of the toxin. For practical purposes, prevention is the only option.
Prevention
This is based largely on the use of vaccines and management aspects aimed at preventing the known predisposing factors. Immunity to enterotoxaemia is produced by two doses of 5 in 1 vaccine given 4 to 6 weeks apart. The first shot of 5 in 1 vaccine should be given on induction of the cattle into the feedlot. As cattle often do not seem to develop a lasting immunity, a third revaccination is indicated for longer term cattle in any feedlots where problems have occurred in the past. Vaccination of all cattle twice 4 to 6 weeks apart with 5 in 1 vaccine also covers any cattle of unknown history against the other clostridial diseases such as blackleg, black disease and malignant oedema. Occasional losses can also occur from these diseases in unvaccinated cattle.
Bovine respiratory disease (BRD)
BRD is the most significant cause of clinical disease, mortality and subclinical reduction of performance in Australian feedlots.
Predisposing factors
These include stress from yarding on the property of origin, transport over long distances, dehydration, feed deprivation for periods greater than 24 hours, saleyard environment, and mixing of groups of cattle providing psychological stress and sources of infectious agents. Once at the feedlot, the environment there provides further stress factors which predispose to BRD. These include further mixing of groups, dust, heat or cold, foreign water, crowding and dietary problems associated with adaptation to the new feed supply.
Infectious agents
These include the viruses infectious bovine rhinotracheitis (IBR), pestivirus (mucosal disease), parainfluenza 3 (PI3) and bovine respiratory syncitial virus (BRSV) and the most common bacterial agents Pasteurella haemolytica and Pasteurella multocida. The predisposing factors combine to give immune suppression. This poor immune response to the infectious agents commonly leads firstly to a viral infection which further compromises the immune response. The end result is a bacterial pneumonia and pleurisy. A recent Meat Research Council (MRC) funded project at six large eastern state feedlots found that all of the bacteria and viruses mentioned above were involved. Most BRD problems occur within the first 30 days on feed. However, in the above MRC project one significant finding was that exposure to IBR virus and seroconversion occurred over the whole feeding period. 87% of animals were susceptible to IBR on arrival and 24% were still susceptible at slaughter. In rare instances, IBR can cause necrotic laryngitis and deaths in its own right but it is more usually found as an early stage of the BRD complex.
Clinical signs
These are often non-specific but include unwillingness to move, nasal and ocular discharge, difficult breathing with extended neck, dropped ears, hollow flank, "dull" eye, disinterest in surroundings, and sometimes a cough. Early detection by well trained, conscientious yard riders is important as treatment must be early to save animals.
Treatment
Treatment should be discussed with your veterinary surgeon. Affected animals should be isolated and treated as soon as they are noticed.
Antibiotic treatment under veterinary advice is appropriate. Remember to record all treatment details such as eartag of the treated animal and the time of the last treatment. Consult your veterinarian for further treatment details.
Prevention
Effective BRD control programs require the input of a specialist consultant feedlot veterinarian, particularly in larger feedlots bringing young cattle long distances to the feedlot. Australian researchers are currently working on local vaccines for the bacteria and viruses involved in BRD. However, even with such vaccines, control of BRD will still remain dependent on a sound veterinary control program which address the predisposing factors.
Blight (Pink Eye)
This is an infectious and contagious disease of cattle occurring worldwide.
Clinical signs
The first sign is a watery discharge from the eye. This soon becomes yellowish with pus and corneal damage follows. It results in temporary blindness, usually in one eye. However the other eye may also become infected. The bacterium Moraxella bovis is involved in some outbreaks but an adenovirus has also been incriminated in some Australian outbreaks. Secondary bacterial invaders then do most of the damage. Warm weather, insects and congregation of cattle are all important factors - hence the problems in feedlots. It has been shown that feedlot steers hospitalised for pink eye grew slower than those not experiencing any health problems. As well as production losses, impaired vision causes added difficulties with husbandry procedures.
Treatment
Treatment should be discussed with your veterinary surgeon. Affected animals should be treated as soon as they are noticed. Strictly observe the correct withholding period as recommended by the veterinarian.
Prevention
Preventive measures are difficult because no vaccine is currently available. Young cattle are more susceptible. British breed cattle are highly susceptible whereas Zebu and Zebu derived breeds are largely resistant. Fly control programs in feedlots will help reduce the spread of Pink Eye. Bush fly baits and buffalo fly treatments are useful in reducing fly populations but again observe the correct witholding period or ESI.
Further reading
Other DPI&F Notes in the Animal Health in Beef Cattle Feedlots series.
Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.
Last updated 09 June 2005
