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Predicting aspects of pork quality becomes increasingly important from both a nutritional and a technological point of view. Little information is, however, available concerning the quantitative relation between nutrient intake and fatty acid (FA) deposition at the whole-animal level. In this study, eight blocks of five littermate barrows were used in a comparative slaughter trial. At 24 kg body weight (BW), one pig from each litter was slaughtered to determine the initial FA composition. The other littermates were assigned to one of four feeding levels (ranging from 70 % to 100 % of intake ad libitum) and were given a diet containing 0.36 g/kg lipid and 0.22 g/kg FA. The temperature for each block was maintained at either 23 or 30 degrees C. At 65 kg, the pigs were slaughtered and the body lipid and FA composition was determined. Seventy per cent of the digested n-6 FA and 50 % of the n-3 FA were deposited. The average composition of de novo synthesised FA corresponded to 1.7, 30.3, 2.4, 19.7 and 45.9 % for 14 : 0, 16 : 0, 16 : 1, 18 : 0 and 18 : 1 FA, respectively. At 23 degrees C and for feeding ad libitum, 33 % of 16 : 0 FA was deposited, 1.7 % shortened to 14 : 0, 63 % elongated to 18 : 0 and 2.8 % unsaturated to 16 : 1. Twenty-eight per cent of 18 : 0 FA was deposited and 72 % unsaturated to 18 : 1. At 30 degrees C, 18 : 0 FA desaturation was reduced by 3.5 %. Feed intake and temperature independently affected the elongation of 16 : 0 FA. A reduction in feed intake increased the elongation rate, whereas the increase in temperature reduced the elongation rate.

A dynamic model was developed to study the effects of diet composition on lipid deposition and fatty acid (FA) composition in pigs. A basic model of protein and lipid deposition was used. Deposited lipids originate from dietary FA and de novo synthesized FA. It is hypothesised that 0.85 of absorbed FA are deposited as-is, and that the composition of de novo synthesized FA was constant throughout growth. Sensitivity analysis indicated that feed intake, efficacy of dietary FA storage and partitioning of de novo synthesized FA had a major impact on FA composition. Evaluation of the model indicated that predictions of protein, lipid, and backfat mass were insufficient, mainly due to the assumption of a constant ratio of lipid to protein mass in the basic growth model. Nevertheless, predictions of the FA composition of backfat and perinephric tissue were reasonable. Differences in FA composition between different tissues could only partly be explained by differences in tissue development. Development of this conceptually simple model was hampered by the limited availability of experimental data on the contribution of dietary lipids to purposes other than lipid deposition, the composition of de novo synthesized FA and the partitioning of FA between different depot sites. [Copyright &y& Elsevier]