The effect of ascorbic acid on the carbohydrate metabolism of vitamin A-deficient chicks

The effect of vitamin A deficiency on some postmortem parameters of avian muscle

The effect of the dietary status of vitamin A on carbohydrate metabolism, postmortem isometric tension development, and shear resistance of Pectoralis major muscle was studied. Depletion studies conducted over a 5-week period indicated a definite influence of vitamin A deficiency on muscle carbohydrate metabolism. Mild hypovitaminosis A induced an increase in glycogen deposition, whereas severe deficiency led to a reduction of these elevated stores. Vitamin A deficiency did not affect the ability of P. major strips to develop isometric tension postmortem. The P. major strips sampled from deficient cockerels generally required longer to reach maximum tension than those of controls. The extended times to maximum tension reflected an increased muscle glycogen content. A significant increase in shear value similarly corresponded to the increased myofibrillar contraction noted in the later deficiency stages. Cockerels which had previously received for five weeks a ration completely deficient in vitamin A were utilized for a two-week repletion study. Although there was a distinct delay in response to the feeding of a vitamin A adequate ration, the muscle glycogen content, isometric tension parameters, and shear values of repleted birds were similar to those of controls within the two-week period.