Omega-3 fatty acids : Physiological and nutritional consequences

Abstract

The addition of menhaden oil (MO) to laying hen rations results in a significant increase in yolk omega-3 (n-3) fatty acid content. Due to proposed cardiovascular benefits associated with n-3 fatty acids, Americans have been encouraged to include sources of these purportedly healthful fatty acids in their diet. Omega-3 fatty acid enriched shell eggs may provide a viable alternative to fish as a source of these fatty acids. In the present study the effects of graded levels of dietary MO on the nutritional and sensory quality of shell eggs, as well as the effect on laying hen physiology, were explored. Graded levels of dietary MO including 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% significantly increased total yolk omega-3 fatty acid content, in a dose dependent manner, when compared to a no-added fat layer ration. Dietary levels between 1.5 and 3.0% resulted in the highest total omega-3 fatty acid incorporation, and these levels were not significantly different (P [less than or equal to] .05) from each other. As the level of dietary MO increased, detection of fishy and medicinal flavor notes increased. Overall sensory quality of scrambled egg was significantly affected by 3.0% dietary MO. Total headspace volatiles were not different although volatile profiles were effected in a dose response manner as MO increased. The correlation of headspace and sensory panel results indicated that MO enriched eggs from dietary feeding of 1.5% MO were more acceptable than eggs derived from hens fed 3.0% dietary MO. While the human consumption of dietary omega-3 fatty acids is potentially beneficial, effects on hen physiology appeared to be deleterious. Hens fed 3.0% MO exhibited increased hepatic lipidosis as compared to hens fed a 3.0% animal/vegetable fat blend. Males fed MO were not effected. Although MO was determined not to directly enhance chick sensitivity to estradiol, data indicated that omega-3 fatty acids may compound the lipogenic effects of estradiol at the level of the liver. Changes in hen serum lipids in response to dietary MO influenced egg size in 22-week-old hens and molted hens. Changes in hen physiology suggested that dietary omega-3 fatty acids significantly affected hen liver lipid metabolism.