[Postnatal development of the fatty acid composition of lipids of adipose and muscle tissue in rabbits on a low-fat diet].

The relative fatty acid profiles of perirenal adipose tissue and muscle tissue of the hind legs were studied in New Zealand rabbits 21 to 140 days old. The rabbits were fed a low-fat diet covering the essential fatty acid requirements and distributed either ad libitum or in rationed amounts. The whole of the fatty acids were established earlier in hind leg muscle tissue than in perirenal adipose tissue. In the latter, the growth allometry of fatty acids in relation to the carcass was already higher between 21 and 74 days (a = 1.39) and distinctly higher between 74 and 140 days (a = 2.68). In the muscle tissue, an isometric phase (a = 0.96) preceded a major allometric phase (a = 1.76). In young suckling rabbits, the fatty acid profile of perirenal lipids was influenced by that of the milk lipids. In the muscle tissue, the presence of a large proportion of phospholipids resulted in a higher percentage of stearic acid and polyunsaturated fatty acids of the (n-6) family (linoleic, dihomo-gamma-linolenic and arachidonic acids). After weaning, the proportion of saturated fatty acids (C greater than or equal to 14) in the perirenal adipose tissue remained constant. The endogenous production of monounsaturated fatty acids (higher allometry) caused a progressive dilution of polyunsaturated fatty acids (lower allometry). This dilution was slowed down when the diet was rationed. Changes in the fatty acid composition of muscle tissue were, in general, comparable to those of perirenal adipose tissue. The differences observed could be attributed to the more active participation of phospholipids in the total lipids of the muscle tissue. Stearic acid, abundant in the phospholipids, showed a lower allometry compared to total fatty acids. Its dilution was an expression of triglyceride dilution of the phospholipids during growth. The same was true of polyunsaturated fatty acids. Rationing had the reverse effect.