EFFECT OF SOYBEAN-OIL AND BEEF-TALLOW SUP PLEMENTATION TO PIG DIETS ON THE FATTY-ACID PROFILE OF BODY LIPIDS

In a growth experiment on castrated male pigs (20-100 kg), the effect of dietrary fat on growth, carcass recovery, and the chemical composit ion of fat in the carcass, giblets and longismus dorsi muscle (m.l.d.) was investigated. Fat tissues in the carcass and giblets were charact erized according to their fatty-acid profile whereas the m.l.d was ana lysed for neutral and complex lipid fractions. The total body composit ion was computed from the chemical composition of the carcass and gibl ets. A total of 23 Large White (VLS) castrates were restrictively fed on diets supplemented with either tallow (treatment R) or soya-oil (tr eatment S) at 2%. Neither growth rate nor carcass recovery were affect ed by the two treatments. The total fatty-acid content deposited in th e carcass and giblets were similar under both treatments (22.0 and 21. 8 kg, and 1.720 and 1.656 kg, respectively). In contrast, the fatty-ac id profile showed significant (P < 0.05) differences. The carcass fat as well as giblet fat of pigs under treatment R contained a higher amo unt of monoenoic acids (1.21 kg and 94 g, respectively) and a lower am ount of polyenoic acids (1.26 kg and 68 g, respectively) in comparison to those in treatment S. These differences were mainly due to the dif ferences in oleic and linoleic acid contents. The saturated fatty-acid content in the carass and giblets was hardly affected by the dietary fat supplements. The neutral lipid fraction of m.l.d. exhibited a simi lar fatty-acid profile to that of the carcass fat. Compared to treatme nt R, monoenoic acid content was 1.75 Mol % lowe and polyenoic acid co ntent was 1.75 Mol % higher in treatment S. In contrast to the neutral lipids, the main component of the complex lipids was polyenoic acids (45 Mol % in treatment R and 51 Mol % in treatment S). From these resu lts, it was revealed that the supplemented fats in feed can also affec t the fractions of the complex lipids. In treatment S, monoenoic acid was 7.4 Mol % lower and polyenoic-acid content was 5.9 Mol % higher th an in treatment R. According to the quantitative analysis of fatty aci ds in the carcass fat, it could be concluded that the polyenoic fatty acids taken up with feed could be largely recovered in the carcass fat irrespective of the fatty-acid composition of the supplemented fats i n both treatments.