Conjugated Linoleic Acid and Fish Oil in Laying Hen Diets: Effects on Egg Fatty Acids, Thiobarbituric Acid Reactive Substances, and Tocopherols During Storage
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Abstract
The effects of incorporating conjugated linoleic acid (CLA) and fish oil in laying
hen diets on egg CLA, n-3 fatty acid, tocopherol, and TBA reactive substances (TBARS)
during 60 d of storage were investigated. Hens were fed corn-soybean meal-based diets
containing 3% yellow grease (YG), 2.75% yellow grease + 0.25% CLA (YG-CLA), 2.5% yellow
grease + 0.25% CLA + 0.25% fish oil (YG-CLA-FO), or 2.75% yellow grease + 0.25% fish
oil (YG-FO). Eggs were collected and stored at 4 degrees C up to 60 d. On storage
d 0, 20, 40, and 60, eggs (n = 8) from each treatment were selected randomly, and
tocopherol and TBARS contents were measured. Egg total lipid and fatty acids were
determined on d 0 and 60 of storage. Feeding YG-CLA-FO led to a 5.4 and 7.7% reduction
in egg total lipids on d 0 and 60 (P < 0.05) when compared with YG eggs. The YG-CLA
and YG-CLA-FO diets led to a 12% increase in egg saturated fatty acids compared with
YG eggs. The content of monounsaturated fatty acids were lower ( > 19%) in YG-CLA
and YG-CLA-FO compared with YG. Egg n-3 was highest in YG-FO eggs and lowest in YG
eggs (P < 0.0001). Storage over 60 d led to a 20 and 67% depletion of CLA in the YG-CLA
and YG-CLA-FO eggs (P < 0.0001). A 29% reduction was observed in the total n-3 fatty
acid content of YG-CLA-FO eggs at d 60 of storage when compared with d 0 of storage
(P < 0.0001). Diet and storage increased TBARS (P < 0.0001), which was highest in
YG-CLA eggs at 60 d of storage. The YG-CLA and YG-CLA-FO diets reduced alpha and gamma-tocopherol
contents at all days of storage compared with YG eggs (P < 0.05). Regardless of diet,
egg storage for 40 d or longer depleted egg tocopherol contents (P < 0.05). These
data demonstrate that healthy eggs with increased n-3 fatty acids and CLA can be generated
by minor diet modifications, but added tocopherol supplementation may be needed to
reduce lipid peroxidation when n-3 or CLA is included in the hen diet.