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Effects of three types of dietary microalgal inclusions on n-3 and n-6 fatty acid profiles in egg yolks of laying hens
Two experiments were conducted to determine if including microalgal biomass into layer diets containing 0, 3, and 5 % flaxseed oil (FO) affected fatty acid profiles in their egg yolk. In Experiment I, 90 Shaver-laying hens (20-wk old) were allotted into 9 groups (n = 10) and fed diets containing 3 levels of FO (0, 3, and 5%) and 3 levels of full-fat Staurosira sp (SS) (0, 7.5, and 10%, Cellana, Kailua-Kona, HI) for 4 wk. In Experiment II, 50 Shaver-laying hens (28-wk old) were divided into 5 groups (n = 10) and fed control diet (without FO and MAB) or the diets containing 3% FO with SS at 7.5%, defatted desmodesmus sp (DS) at 7.5%, or defatted nannochloropsis ocreanica (NO) at 7.5 or 15% for 4 wk. Body weights, feed intakes, and egg quality (albumen, egg yolk, and egg shell weight) were measured weekly, and fatty acid contents of egg yolk were determined biweekly. In Experiment I, neither FO nor SS affected feed intakes, egg production, or egg quality. While body weights were decreased (P < 0.05) by 5% FO, the decrease was prevented by the inclusion of SS. At wk 2, the FO inclusion increased n-3 fatty acid (P < 0.05), and decreased n-6 fatty acid concentrations in the yolk. The SS inclusion affected (P < 0.05) yolk n-6 fatty acid concentrations. At wk 4, there were interactions (P < 0.05) between SS and FO on the yolk n-3 fatty acid concentrations or changes over time. The yolk concentrations of n-6 fatty acids were increased by FO, but decreased by SS. In Experiment II, egg production, egg component weights, body weights, and feed intakes were not affected by the 5 dietary treatments. While the combinations of 3% FO and three types of microalgal biomass elevated (P< 0.05) the yolk n-3 fatty acid contents, the two doses of NO (7.5 vs. 15%) showed no difference. In conclusion, inclusions of three types of microalgal biomass exerted moderate effects on n-3 and n-6 fatty acid profiles and concentrations in comparison with the much stronger effects of 3 or 5% FO. However, the microalgal biomass inclusion seemed to help offset the negative effects of 5% FO on the body weights of laying hens. (Supported in part by USDA/DOE Biomass R&D Initiative Grant).
Keywords: Microalgal biomass, omega-3 fatty acid, laying hens