Effect of Dietary Histidine on Tissue Concentrations of Histidine-containing Dipeptides in Adult Cockerels

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Abstract
Six groups of 7-month old White Leghorn cockerels were fed histidine at 0, 0.3, 0.6, 0.8, 0.11 and 0.22% of the diet, representing 0, 25, 50, 75, 100 and 200% of the histidine maintenance requirement, respectively. Histidine was isonitrogenously replaced with glycine. After 12 weeks, body weight was significantly lower with all concentrations of dietary histidine below the requirement level, while food intake was decreased only upon feeding the histidine-free diet. Anserine in leg muscle, pectoral muscle and brain showed no significant change in concentration with varying histidine intake, although carnosine, homocarnosine, and free histidine generally showed a significant and direct dependence on the level of histidine intake. A few birds that had been fed the histidine-free diet for 8 weeks were repleted by being fed twice the histidine maintenance requirement for the subsequent 4 weeks; the concentrations of all histidine-containing compounds reverted to starting levels. Blood hemoglobin also decreased when histidine intake was reduced below the maintenance requirement. The present study confirms the indispensability of histidine for the adult cockerel and the level of 0.11% of diet as an adequate estimate of requirement for maintenance of body weight, normal hemoglobin concentration, and the prevention of decreases in the concentrations of histidine dipeptides and of free histidine in muscle and brain tissue. Species differences in anserine and carnosine concentrations were noted between the adult cockerel and the adult rat.