Swine: Thiamin

Deficiency

Thiamin deficiency in swine reveals itself particularly in a decrease of appetite and body weight, vomiting, a slow pulse, subnormal body temperature, nervous signs, postmortem heart changes and sudden death because of heart failure. Animals consuming a low-thiamin diet soon show severe anorexia, lose all interest in food and will not resume eating unless given thiamin (Illus. 1). If the deficiency is severe, thiamin must be force-fed or injected to induce animals to resume eating.

Heinemann et al. (1946) reported that the pig can utilize stored thiamin over a long time, as 56 days was required for the pigs to lose their appetites after beginning a thiamin-deficient diet. Death has been reported 74 days after pigs began a thiamin-free but otherwise adequate diet (Loew, 1978). For young pigs, severe thiamin deficiency has resulted in death at the age of three to four weeks.

First signs of thiamin deficiency in pigs are reduced feed consumption and vomiting, with a sharp reduction in weight gains (Van Etten et al., 1940; Miller et al., 1955; Peng and Heitman, 1973). Functional and structural cardiac changes are the main findings in experimentally deficient swine; in contrast to clinical reports, nervous system lesions were not detected (Follis et al., 1943). Electrocardiographically demonstrable changes in heart tissue are also seen, with enlarged hearts obtained from pigs receiving thiamin-deficient diets (Illus. 2). The heart can be flabby, as reported by Van Etten et al. (1940), with myocardial degeneration. On microscopic examination, it is possible to recognize inflammations and necrotic changes in the myocardial fibers.

Thiamin-deficient animals have elevated plasma pyruvate concentrations (Miller et al., 1955), since with the deficiency of the vitamin there is an accumulation of intermediates of carbohydrate metabolism. The red blood cell enzyme transketolase is lowered in thiamin-deficient pigs, with this enzyme used as an indicator of thiamin status (McDowell, 2000). Peng and Heitman (1973) determined that erythrocyte transketolase and TPP stimulation were very useful, sensitive and specific methods to study thiamin status of growing-finishing pigs.

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