Relationship between food and water ingestion in the rabbit

¹ Department of Physiology, Columbia University, New York City

Studies of ad libitum food-water intake relationship were made on 146 rabbits over a period of 7 1/2 years. Fluid intake was considerable, averaging at least 200 cc/day. Though daily variations occurred, major deflections from this mean were rare. Six-month studies revealed a quantitative linear relationship between food and water intakes. This relationship was altered somewhat by age since both water and food intake continue to decrease with time, water at a slightly greater rate than food. When food was suddenly removed, male rabbits consistently displayed a syndrome of polydipsia and polyuria. Balance studies revealed a sodium chloride deficiency. This caused polydipsia because substituting saline for drinking water abolished enhanced drinking. Equimolar solutions of potassium chloride were without such an effect. Female rabbits showed variable responses to food deprivation, depending on age. When young, the response was polydipsic. Repeated food deprivations resulted in decreasing responses as the rabbit matured; as aging continued, the responses reverted back to a polydipsic phase. Castration of females abolished this cyclic response.