Influence of vitamin A deficiency on the gross efficiency of growth of rats.

It seems important to find out whether the well-known impairment of growth due to vitamin A deficiency is caused directly by a decrease in appetite and food consumption, such as seems to be the case in thiamine deficiency, or whether a failure in the utilization of the food consumed is not the first symptom. A measurement of the gross efficiency of growth is a classical method to determine this, gross efficiency being defined as energy output (new tissues)-1 It can be expressed in energy input (aliments ingested)-calories per calorie, or in grams per calorie, or in grams per gram. In this study we have expressed our results in grams of weight gained per gram of ration eaten, as we are most interested in relative efficiencies. Since few, if any, studies have been made on the symptomatology of vitamin A deficiency with "synthetic rations, " we have used a complete "synthetic " ration in the present study. Such a diet is much more