Abstract
In order to study the distribution of and the changes in composition of fatty acids in the longissimus muscle, seven Holstein steers were fattened for 100-day (3 steers) and 200-day (4 steers) periods after being grazed. Samples of each longissimus muscle of the 4th, 6th, 8th, 10th and 12th thoracic vertebrae sections and of the 1 st, 3 rd and 5th lumbar vertebrae sections were taken for determining fatty acid composition of total lipids. There were no statistical differences in the fatty acid composition of the longissimus muscle sections between the 100-day and 200-day fattened steers. However, C18:0 was observed to decrease slightly and C 18:1 to increase slightly during the second 100day fattening period. The portions of longissimus muscle from the 4th, 6th, 8th and 10th thoracic vertebrae sections were found to have more C 16:0 and C 18:0 and less C 16:1, C 18:1 and total unsaturated fatty acid than the portions from the 12th thoracic vertebrae and from the 1 st, 3 rd and 5th lumbar vertebrae sections. This difference in fatty acid distribution may be related to differences in growth rate within the longissimus muscle.
