EFFECTS OF FISH-MEAL IN BEEF DIETS ON GROWTH-PERFORMANCE, CARCASS CHARACTERISTICS, AND FATTY-ACID COMPOSITION OF LONGISSIMUS MUSCLE

We investigated the effects of fish meal (FM) in beef cattle diets on growth performance, carcass characteristics, and fatty acid (FA) compo sition of longissimus muscle in 63 yearling steers (335 +/- 23 kg). Hi gh-moisture corn and alfalfa silage diets were supplemented with eithe r a corn gluten/blood meal mixture or FM at 10% of the diet. Fish meal contained (as-is basis) 5.87 g/kg eicosapentaenoic acid (EPA) and 9.8 4 g/kg docosahexaenoic acid (DHA). Seven strategies were developed to feed either a control diet (no FM) or diets containing 5 or 10% FM wit h FM fed for either 56, 112, or 168 d before Slaughter. Average daily gain and feed efficiency were not affected (P > .10) by FM feeding but DMI decreased. Within FM diets, cattle fed 5% FM consumed more (P < . 01) DM and gained more (P < .02) than cattle fed 10% FM. Carcass trait s were not affected (P > .05) by feeding strategy except for fatter (P < .05) and lower (P < .06) yielding carcasses in cattle fed 5 vs 10% FM diets. Fish meal feeding increased (P < .01) concentrations of (n-3 ) FA, including EPA and DHA, and decreased (P < .05) concentrations of arachidonic acid. Increasing the amount of dietary FM further increas ed (P < .01) concentrations of EPA and DHA and decreased (P < .05) con centrations of (n-6) FA. We estimate that a 114-g steak from cattle fe d 10% FM would supply 35 to 90% of the current average daily intake of EPA and DHA in North America. The results indicate that FM may have a role in niche marketing of beef provided that eating quality is not c ompromised.