LAUSR

Abstract There is an increased interest among poultry nutritionists to increase the linoleic acid (LA) content of the egg, which possesses many benefits for human health. This fatty acid must be provided by the diet as the bird’s body cannot synthesise it. The present study evaluated the influence of different levels of dietary LA on the productive performance, egg quality and yolk lipid profile of Longyan laying ducks. In total, 900 Longyan female laying ducks aged 24 weeks were assigned to six dietary treatments, each containing 6 replicates of 25 ducks. The six dietary treatments contained six incremental levels of LA (analysed content: 0.36, 0.66, 0.80, 1.07, 1.28, and 1.45%) and the experimental diets were offered for the following 20 weeks. The results showed that different supplemental levels of dietary LA had no effects on egg production traits, concentrations of plasma cholesterol and triglycerides, or low or high-density lipoprotein cholesterol (p > .05). There was a linear increase in yolk colour (p < .001) and yolk cholesterol (p < .005) with increasing dietary LA. With increased intake of LA, the yolk content in C18:1, C20:1 and total monounsaturated fatty acids decreased linearly (all p < .005), but the concentrations of C18:2, C18:3, C20:2, C20:3, C20:4, C20:6, and total polyunsaturated fatty acids were linearly increased (p <.008 to <.0001). The results of the present work show that LA dietary supplementation of Longyan duck layers positively modified the yolk fatty acid profile, increased the yolk cholesterol, and enhanced the yolk colour. HIGHLIGHTS Linoleic acid (LA) is an essential fatty acid that must be added to the poultry diet. This study evaluated six dietary levels of linoleic acid in laying ducks. LA dietary supplementation modified yolk colour, cholesterol and fatty acid profile.