Depot species differences

The major fat depots of animals include subcutaneous fat (located under the skin and overlying superficial muscles) and intermuscular fat (located between muscles). Appreciable amounts of fat also are deposited in the abdominal cavity and other internal sites. The distribution of fat between different sites varies somewhat with animal species, breed, and degree of finish. 

Animal and plant depot lipids consist primarily of triacylglycerols triesters of glycerol and three fatty acids. Lipids differ from species to species with regard to the types and amounts of fatty acids they contain. Table 1 presents the fatty acid... 

P) Rats, The rat differs from other species in the whole-body retention, excretion, and distribution of iAs and its metabolites. In an early study, CouLSON and associates (1935) reported that rats excreted As derived from ingestion of shrimp faster than iAs which was added to the diet. Hunter and coworkers (1942) noted that the erythrocyte was the major depot for As following administration of iAs. Subsequent studies have confirmed the high accumulation and retention of As in the rat erythrocyte. In a comparison among species 48 h after intramuscular administration of sodium p" As ] arsenate, Lanz and coworkers (1950) found that the blood compartment of the rat accounted for nearly 45% of the administered dose of " As. In contrast, the blood compartment in cat accounted for 5.6% of the administered dose in dog, 0.1% in rabbit, 0.27%, in guinea pig, 0.25% in chicken, 0.19% and in mouse, 0.07%. 

The metabolism of inorganic ions, or simply mineral metabolism, differs in one essential point from the metabolism of substances discussed so far. In contrast to proteins, carbohydrates or fats, minerals are neither produced nor consumed in the organism. Their intake from food can be regulated only very roughly, if at all. Most animal species, nevertheless, in the course of evolution have developed the ability to keep the concentration of ions constant in the body fluids, thus providing a constant milieu interne. This is achieved principally by regulating excretion. Several ions have special depots which can be mobilized in periods of insufficient intake. 

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