EFFECTS OF DIETARY ALPHA-LINOLENIC ACID AND STRAIN OF HEN ON THE FATTY-ACID COMPOSITION, STORAGE STABILITY, AND FLAVOR CHARACTERISTICS OF CHICKEN EGGS

A study was conducted to determine the effect of dietary alpha-linolenic acid on the fatty acid compositions of egg yolk lipids, tocopherols, and internal quality of raw eggs during storage and the sensory characteristics of hard-boiled eggs from six different laying hen strains. Laying hens (total 300 birds, 72 wk old) from six strains (Rhode Island Red, Barred Plymouth Rock, New Hampshire, Light Sussex, Brown Leghorn, and White Leghorn) were distributed in 12 floor pens (2 pens per strain, 25 birds per pen) with male roosters. One of the pens for each strain was fed with tallow-based control diet and another was assigned with 3% alpha-Linolenic acid (LNA) enriched diet with 120 U of mixed tocopherol/kg diet for 3 mo. Ten eggs from each pen were collected every day after 2 wk with the experimental diets, and stored in a cold room at 4 C up to 4 wk. Total lipids, fatty acid compositions, Haugh units, and tocopherols of egg yolk were determined once a week during the 4-wk storage periods. Sensory studies were also conducted using the eggs stored for 2 wk at 4 C. Dietary LNA increased the amount of n-3 fatty acids (6.5%) In total lipid, and over 70% was C-18:3n3, and the rest was C-22:6n3 (20 to 25%) and C-22:5n3 (5 to 10%). Only minor differences in fatty acids among strains were observed. The differences and the changes in tocopherols during storage periods by strain and diet appeared randomly and lacked consistency. The amount of tocopherols in yolk and the internal quality of raw eggs were not changed during storage periods. The flavor scores of eggs from control diet were more favorable than those of eggs from LNA diet, but their differences were minor. This result indicates that laying hen strains is not an important consideration in the dietary modification of fatty acid of shell eggs.