Theoretical quantitative approach to the mechanism of hypoglycemic ketosis in ruminants

Abstract

Clinical hypoglycemic ketosis in domestic ruminants is related to the overall energy balance of the animals. The condition occurs characteristically in dairy cows with high milk yields and in pregnant ewes bearing multiple foeti in utero. Both of these reproductive phenomena are characterized by high demands on glucose resources. The glucose resources of cattle and sheep are limited because ruminant nutrition is characterized by bacterial fermentation in the rumen which converts carbohydrates and cellulose into steam volatile fatty acids. The ratio of ketogenic to glucogenic volatile fatty acids varies with the diet. The relative amount of ketogenic metabolites available for maintenance requirements after the demands for reproductive processes have been met will determine the predisposition to hypoglycemic ketosis. This concept is represented quantitatively by the following equation: f m= (C in ×f in )−C prod ×f prod ±(C d×f d) C m ƒ refers to fraction of energy which consists of fat precursors which cannot be converted to glucose, C to calories, m to maintenance requirements, in to food intake, prod to energy produced and d to depot energy. As ƒ m increases, the predisposition to hypoglycemic ketosis will increase and existing hypoglycemic ketosis will become more severe. Addition of energy which is limited to fat precursors will only exacerbate the ketosis; thus the problem is not necessarily one of energy deficiency but rather of relative glucose starvation.