The Effect of Method of Feeding upon the Susceptibility of the Pig to Parakeratosis

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Abstract
The effects of various methods of feeding on the development of parakeratosis in growing swine were studied. “High calcium” rations were fed. Ad libitum-feeding, dry (self-feeding) was the most detrimental, while a combination of wetting the feed and supplying limited amounts of feed only twice a day (hand-feeding, wet) significantly stimulated body weight gains and reduced the severity of the parakeratotic skin lesions. Neither ad libitum-feeding, wet nor hand-feeding, dry alone had much beneficial effect on parakeratosis or on weight gains. Although in this study hand-feeding, wet proved beneficial, the response was significantly less than that obtained by supplementing the ration with 100 ppm of zinc. Altering the method of feeding did not affect weight gains or produce skin lesions in pigs receiving 100 ppm of supplemental zinc. This suggests that hand-feeding, wet may increase the availability of natural dietary zinc for the control of parakeratosis. Experiments performed in vitro demonstrated that zinc was readily removed from solution during the precipitation of calcium phosphates brought about by increasing from 3 to 6 the pH of solutions of calcium, phosphate and zinc. These conditions simulate somewhat the change in pH of ingesta during its passage from the stomach of the pig into the small intestine. Decreasing the Ca:P ratio of these solutions by varying the phosphate concentration markedly decreased the amount of zinc removed from solution. Possible relationships of zinc binding by calcium phosphates to the antagonistic effects of high dietary calcium on parakeratosis in swine and to the beneficial effect of hand-feeding, wet were discussed.