Low levels of dietary vitamin A increase intramuscular fat content and polyunsaturated fatty acid proportion in liver from lean pigs

The effect of the dietary vitamin A level and administration time on intramuscular fat (IMF) percentage and fatty acid composition of the subcutaneous outer layer, intramuscular and hepatic fat from lean pigs was investigated. One group received 13,000 IU of vitamin A/kg diet for 11 weeks (H); other group received 1300 IU during the same period (L) and a third group received a vitamin A-enriched diet (13,000 IU) for six weeks followed by a diet with 0 IU of vitamin A for the last five weeks previous to slaughter (H-0). The dietary vitamin A level had no effect on growth performance and carcass traits. Pigs fed L showed higher IMF in Longissimus dorsi muscle when compared with group H. The L group also showed a higher saturated fatty acid (SFA) proportion and decreased MUFA/SFA ratio in the subcutaneous backfat outer layer. The dietary vitamin A level had no effect on the fatty acid composition of muscle. The suppression of vitamin A five weeks prior to slaughter did not affect IMF and fatty acid composition of the subcutaneous backfat outer layer, while in liver decreased SFA and increased PUFA.