The objective of this study was to examine the incorporation of dietary n-3 fatty acids (FAs) into ovarian compartments and the effects on hormonal and behavioral patterns around estrus. Multiparous 256-day pregnant cows were fed either a standard diet both prepartum and postpartum (PP) (control; n=22) or supplemented with extruded flaxseed (E-FLAX) providing C18:3n-3 at 172.2 and 402.5 g/day per cow prepartum and PP respectively (n=22). The estrous cycle was synchronized, and at day 7 of the

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... cle, the cows were injected with prostaglandin F2α (PGF2α) and then subjected to 5 days of intensive examination. Compared with those in the control, in the E-FLAX group, the interval from PGF2α injection to behavioral estrus peak tended to be longer (3.6 h; P<0.1), that to estradiol (E2) peak was 6.5 h longer (P<0.03), and that to LH peak tended to be longer (5.3 h; P<0.07). The durations of behavioral estrus and E2 surge were longer, and the area under the E2 curve was greater in the E-FLAX cows. Afterward, 7–8 days following behavioral estrus, follicular fluids (FFs) from >7 mm follicles were aspirated. The proportions of n-3 FA increased in plasma, FF, and granulosa cells in the E-FLAX group. The concentrations of PGE2 in the E2-active follicles tended to be lower in the E-FLAX cows (P<0.06). In conclusion, several modifications in hormonal and behavioral estrus patterns were demonstrated in cows fed n-3 FA, which might be attributed to alterations in membrane FA composition and partly mediated by lower PGE2 synthesis.