Determination of Linoleate Requirement of Swine by a New Method of Estimating Nutritional Requirement

A new method of estimating minimum nutrient requirements is proposed which is particularly well suited to the interpretation of tissue analysis or weight gain data. For the first step of this procedure, exponential equations were fitted to the curves relating tissue PUFA concentration to dietary linoleate concentration. Constants derived from these equations were then used to demonstrate that there are 4 distinct metabolic processes related to linoleate nutrition. Two of these were found to correspond to linoleate requirements of 0.6 and 1.5% of calories, respectively. The former of these (0.6 Cal./100 Cal. of diet) was associated with the decrease in tissue diene and increase in tissue triene that is observed as linoleate intake decreases. The latter (1.5 Cal./100 Cal. of diet) was associated with tetraene metabolism in the tissues, and total body weight gain. The other two metabolic processes were not interpreted in terms of nutritional requirements. One was related to the storage of excesses. The other was associated with tissue lipid changes observed at linoleate intakes below 0.4% of calories, and might be referable to variations of linolenate in the diets used in this experiment. These latter changes appear complex and require further study before interpretation.