ABSTRACT
This experiment was conducted using 288 Hisex White laying hens, 32 weeks old, for a period of 10 weeks, with the objective of studying the fatty-acid enrichment of the egg yolk of hens fed diets supplemented with fish oil (OP) or marine algae (AM) to provide five levels of docosahexaenoic acid (DHA) of 120, 180, 240, 300 and 360 mg/100 g diet for each source. A 2x5 completely randomized factorial design with three replicates of eight birds per treatment was applied in order to have the following groups: OP120, OP180, OP240, OP300, OP360, AM120, AM180, AM240, AM300 and AM360. A control group submitted to a corn/soy basal diet (CON) and another one supplemented with marine algae at the level of 420 mg of DHA/100 g diet (AM420) were also used. The arachidonic acid (AA), linoleic (AL) and n-6 PUFAs showed significant decreases (P < 0.05) with the increase of fish oil in the diet, ranging, respectively, from 98.71 mg, 987.70 mg and 1108.92 mg/yolk in the CON diet to 38.87 mg, 734.22 and 802.79 mg/yolk, for the group OP360. For the fish-oil source, the average amount of arachidonic acid also showed linearity (X + Y = –0.16 89.40, R2 = 0.86), decreasing from 98.71 mg/yolk (CON) to 38.87 mg/yolk (OP360) and 77.79 mg/yolk (AM420), while the total of n-6 PUFAs ranged from 1108.92 mg/yolk (CON) to 802.79 mg/yolk (OP360) and 1178.19 mg/yolk (AM120). The percentage of incorporation of arachidonic acid in the yolk of eggs decreased linearly with increasing levels of DHA in feed supplemented with fish oil and marine algae, from 4.81% (CON) to 2.57% (OP360) and 3.51% (AM420). The averages of 1572.11 mg/yolk (fish oil) and 2118.16 mg/yolk (marine algae) of the total consumption of n-6 PUFAs, and 3.12% (fish oil) and 4.30% (marine algae) of the incorporation of AA into yolk differed (P < 0.05) between sources. A significant decrease (P < 0.05) was noted in the n-6/n-3 ratio, varying from 17.50 (CON) to 3.72 (OP360) and 6.36 (AM420).
KEY WORDS
Arachidonic acid; fatty acids; hens’ eggs; fish oil; marine algae