Conjugated linoleic acid and fish oil in laying hen diets: effects on egg fatty acids, thiobarbituric acid reactive substances, and tocopherols during storage.

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.