Vitamin E is widespread in feed stuffs including vegetable oils, cereals and green plants but problems arise often from using polyunsaturated fats in diets as sources of energy which destroys the vitamins. Vitamin E is necessary for the optimum function and metabolism of the nervous, muscular, circulatory and immune systems. It helps to maintain the integral structure of muscles in the digestive and reproductive systems and is involved in the synthesis of certain amino acids and vitamin C. It has a close relationship with selenium metabolism. The less selenium in the diet the greater is the requirement for vitamin E.
The recommended requirements are 30 to 100iu/kg in the grower ration and 30 to 60iu/kg in the finisher ration. These levels are probably higher than those necessary for maximum growth, which may be 50% less. When polyunsaturated fatty acids (PUFA) are added to diets 3iu of vitamin E should be added for each g of PUFA.
Symptoms
Piglets
- Become sensitive to iron injections if sows deficient.
Sows
- N/A
Weaners & Growers
Clinical signs and post mortem lesions of a deficiency vary according to the system affected and include:
- Sudden death in rapid growing pigs without any prior clinical signs.
- Possibly increased levels of concurrent diseases if selenium levels are low.
- Pale pigs.
Post-mortem symptoms are characteristic and include:
- Large amounts of fluid around the heart and lungs.
- Haemorrhagic and pale areas in heart muscle.
- Fluid in the abdomen with pieces of fibrin.
- Pale muscle areas (necrosis) particularly in the lumber muscles and hind muscles of the leg which contain excesses amounts of fluid.
- If the liver is involved it is enlarged and mottled with areas of haemorrhage interspersed with pale areas.
Vitamin E and selenium related diseases
- Gastric ulcers – These are often caused by stress but the incidence increases where vitamin E levels are low.
- Hepatosis dietetica – Death of liver cells.
- Muscular or nutritional dystrophy. Degeneration of skeletal, smooth or cardiac muscle fibres. Fluid often accumulates around muscles.
- Mulberry heart disease (MHD). A disease of the heart muscle resulting in sudden death.
Causes / Contributing factors
- Diet i.e. high levels of fat.
- Vitamin A deficiency.
- Vitamin E and selenium deficiency.
- Rapid growth may be a contributing factor.
- High stocking densities may predispose.
- Grains stored with high moisture content in high temperatures and with fungal growth may have low levels of vitamin E.
Diagnosis
Accurate diagnosis requires histological examinations of the liver, heart or skeletal muscle. Serum samples should be taken from pigs at risk and tested for levels of vitamin E.