There is an urgent need to evaluate and introduce alternatives for the unsustainable and traditional feed
stuffs in poultry. This study evaluated the effects of graded replacement of soybean meal (SBM) by peanut
meal (PNM) on egg production, egg quality, oxidative status, and yolk fatty acid profile in laying ducks. In
total, 360 Longyan ducks aged 21 weeks were allocated to five treatments, each containing six replicates
of 12 birds. Birds were fed the diets containing PNM replacing 0 (control), 25, 50, 75 or 100% of SBM for
16 weeks. With the increase of PNM level, egg production was improved (quadratic, P < 0.05), egg weight
and feed consumption were decreased, feed conversion ratio and egg mass were impaired at 100% PNM,
and yolk colour was enhanced (quadratic, P < 0.05). Plasma malondialdehyde concentration was
increased at 100% PNM, while plasma glutathione concentration was decreased (quadratic, P < 0.01) as
PNM substitution increased. Total cholesterol content in yolk decreased (P < 0.01) in response to
increased PNM substitution. The contents of saturated fatty acids C20:0 and C22:0 in yolk increased (linear
or quadratic, P < 0.05) with increased PNM substitution, but the contents of saturated fatty acid C18:0,
monounsaturated fatty acid C22:1, and polyunsaturated fatty acids C18:3n-3 and C22:6n-3 in yolk were
decreased (linear, P < 0.05) as PNM replacement increased. The contents in yolk of polyunsaturated fatty
acid C18:2n-6, C20:2n-6, C20:3n-6, C20:4n-6, and total amount of polyunsaturated fatty acids increased
with the highest contents obtained at 75% PNM substitution. The ratio between n-6 and n-3 increased
(linear, P < 0.05) as PNM substitution increased. The transcript abundance in liver of peroxisome
proliferators-activated receptors c and fatty acid synthase showed quadratic (P < 0.05) responses with
PNM replacement, with the highest expression of both genes being obtained with 75% substitution with
PNM. Replacement of dietary SBM with 100% PNM decreased egg production and antioxidant capacity
and increased the ratio of omega fatty acid in yolk between n-6 and n-3 in laying ducks. The obtained
results indicate that PNM can be used to replace up to 75% of SBM in the diet of laying ducks without
negative effects on the egg-laying production or egg quality. The regression model indicated that the
maximal egg mass was obtained at no more than 67.6% replacement of SBM with PNM in the diet of laying
ducks.