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THE FAT COW SYNDROME A condition caused by excessive energy intake in dairy cattle in late lactation and the dry period which is exacerbated by a low protein intake over the same period. These cows become over-fat, with excessive subcutaneous fat depots which are mobilised to the liver at the time of greatest demand i.e. post-calving and early lactation, and the subsequent deposition of fat in the liver results in metabolic problems e.g. hypocalcaemia, acetonaemia and an increase in periparturient infections e.g. mastitis. The condition is an exacerbation of what is known to happen in more than 70% of apparently normal high-yielding dairy cattle in the U.K. as they change from a state of positive energy balance to one of negative energy balance at parturition. CLINICAL SIGNS Cows that are very fat during the dry period and at calving have an increased incidence of periparturient problems e.g. hypocalcaemia etc. which are unusually resistant to treatment. The severely affected cases have reduced appetites eventually becoming totally anorexic and subsequently ketotic although there is no response to treatment. These severe cases usually die or are culled within 10 days. In less severe cases milk yields are dramatically reduced, metritis, mastitis, lameness are common as incidental findings, and in animals which are kept the body condition suddenly deteriorates 3-4 weeks after calving. Anoestrus and suboestrus are a problem and lactation is usually severely curtailed. DIAGNOSIS Usually a group problem but may affect individuals e.g. show cows or dominant cows in a herd. If the above clinical signs are present then a diagnosis can be made using a mathematical calculation involving blood glucose, AST and free fatty acid levels as an estimate of fatty infiltration of the liver. Liver biopsy can be used to confirm this condition. TREATMENT Treatment of over-fat pregnant cows is of little value and affected cases should be slaughtered. Cases not diagnosed till after calving usually prove resistant to treatment and are also probably better culled as they prove to be economic disasters if kept. CONTROL Dairy cows should be prevented from becoming over-fat during late lactation and the dry period by keeping energy intake down and maintaining a balanced ration. Feeding should be closely monitored to ensure that cows are not over-fed and dairy cows should be ‘lead-fed * and not steamed-up |
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