Genetic and nutritional effects on the fatty acid composition of subcutaneous and intramuscular lipids of steers.

Genetic and nutritional influences on fatty acid composition of subcutaneous (SNL) and intramuscular neutral lipids (IMNL) and intramuscular phospholipids (IMPL) of steer carcasses were investigated by removing the effect of carcass fat percentage (CFP) or slaughter age (SA) on the fatty acid composition. To investigate the genetic influences, steer progenies from two dam breed-types (Japanese Black (JB) and f(1) between JB bull and Holstein cows) and three different maturing types of JB sires were used. Dam breed-type did not affect any of the fatty acids except 17:0 in SNL and none of those in IMNL. Percentages of 16:0, 16:1, 18:2, SFA, MUFA and PUFA in SNL differed among sires of JB dam breed-type group (p < 0.05) even after removing the effect of CFP. Studies on the effects of two nutritional planes [high(H) and medium-high(MH)] on the fatty acid composition of SNL, IMNL and IMPL were done using JB steers. The SNL and IMNL of the H plane steers contained greater percentages of saturated fatty acids at the same CFP but less at the same SA than the MH plane animals. The reverse was true for the unsaturated fatty acid contents.