Optimising Beef Fatty Acid Composition and Lipid Quality through Silage Type and Feeding Intensity during the Finishing Period

The quality of beef fat depends not only on its amount but also on fatty acid composition and lipid quality indices, which are strongly influenced by feeding strategies applied during the finishing period. The aim of this study was to evaluate the effects of silage type and feeding intensity on intramuscular fat deposition, fatty acid composition, desaturase activity indices and lipid quality indices in finishing Holstein–Friesian bulls. Thirty-two bulls were assigned to a 2 × 2 factorial experiment and fed total mixed rations for 120 days. Intramuscular fat content and fatty acid composition of the longissimus lumborum muscle were determined by gas chromatography, and lipid quality indices were calculated from the fatty acid profile. Increasing feeding intensity sig-nificantly increased intramuscular fat content and the absolute amounts of most fatty acid groups, whereas silage type mainly affected fatty acid composition by increasing the proportion of n−3 fatty acids and reducing the n−6/n−3 ratio in grass silage–based diets. Significant interactions between silage type and feeding intensity were observed for selected fatty acids, indicating that the response to increased dietary energy supply depended on the forage base of the diet. Despite marked changes in fatty acid composition, lipid quality indices (including AI and TI) were only moderately affected. Overall, these results indicate that feeding intensity primarily controls the extent of lipid deposition in beef, while silage type modulates fatty acid composition, emphasising the importance of combined dietary strategies for improving the nutritional quality of beef fat.