Abstract:
Two experiments were conducted to determine the effect of various levels
of vitamin E on egg yolk. A diet of corn-flax-soybean meal was fed to layers and
α-tocopherol content in eggs, egg production, and egg quality were evaluated. In
experiment 2, vitamin E toxicity was also determined. In experiment 1, 192 laying
hens were divided into 12 treatments of 16 birds/treatment and fed diets mixed to
contain either 5, 10, 15, 20, 25, 100, 200, 250, 350, 400, 550, or 700 IU/kg of
vitamin E for four weeks. Hens were selected at random and were placed in four
replicate groups with four birds per replicate. Egg weight and α-tocopherol level in
eggs showed significant increases with increased dietary α-tocopherol (P<0.05).
In experiment 2, 96 layers were divided into 6 groups and fed diets formulated to
contain 15, 250, 500, 1000, 2000, or 3000 IU α-tocopherol/kg of feed. The average
egg yolk produced by hens fed the experimental diets contained 153, 356, 607, 684,
1549, and 1394 μg of α-tocopherol/g of yolk (0.168, 0.392, 0.668, 0.752, 1.704,
and 1.533 IU α-tocopherol/g of yolk), respectively, after four weeks of feeding the
experimental diets. Egg weight, yolk color, and yolk weight showed a significant
increase (P<0.05) over the four weeks of the experiment, while albumen height
significantly decreased (P<0.05). Egg weight, albumen height and yolk weight
significantly increased (P<0.05) in the higher vitamin E treatment groups, while
yolk color significantly decreased (P<0.05) as the vitamin E supplementation
levels increased. In both experiments the vitamin E level in the feed significantly
increased the α-tocopherol content in the yolk (P<0.05). No signs of toxicity
were noticed at necropsy. This study indicates that chicken eggs can be enriched in
their vitamin E content. The human Recommended Daily Allowance (RDA)
requirement for vitamin E are met and exceeded with the consumption of one egg.
