Assessment of eggshell color and yolk fatty acid profiles in two laying hen strains housed with or without access to legume or aromatic plant species outdoor

Abstract

Plant species vary regarding aspects including taste, palatability, and bioactive compounds. Consequently, the intake of different plant species by laying hens results in the consumption of associated nutrients and the expectation is the modification of shell color and fatty acid profiles of egg yolk. Here, we investigated the effect of housing environment on shell color and yolk fatty acid profiles of Lohmann Sandy (LS) and Lohmann LSL Classic (LW) strains. Housing environments included deep litter (DL), free access to outdoor Mentha piperita (M. piperita), Petroselinum crispum (P. crispum), and Medicago sativa (M. sativa). 260 four-week-old birds were randomly distributed to DL and outdoor plant-associated groups, with four and three replicates, respectively, and 10 birds per replicate. Range accessibility was granted at 12 weeks of hen age for outdoor plant-associated groups. Shell color and yolk fatty acid profiles were analyzed at 25 weeks of hen age. There was greater variability among the housing environments regarding the shell color: redness (a*) and yellowness (b*) at the broad end, lightness (L*), a*, b*, and shell color (∆E*) at Centre and pointed end (P<0.01; P<0.05). The overall ∆E* was also significantly highest in eggs collected from M. sativa and P. crispum hens and lowest in eggs from M. piperita hens. Palmitic (C16:0), stearic (C18:0), oleic (C18:1n9c), linoleic (C18:2n6), and alpha-linolenic (C18:3n3) fatty acids were significantly higher in eggs obtained from M. sativa and M. piperita than DL and P. crispum hens, each category with similar values (P<0.01; P<0.05). While the total saturated fatty acids were highest and lowest in M. sativa and P. crispum, respectively, total unsaturated fatty acids were highest and lowest in P. crispum and M. sativa, respectively (P<0.01; P<0.05). No differences were observed in myristic acid (C14:0) and arachidonic acid (C20:4 n-6) among the housing environments (P>0.05). Additionally, all the fatty acid contents in yolks were similar between the laying hen strains (P>0.05). It was concluded that most of the fatty acid contents in egg yolk could be modified when hens are granted free access to outdoor M. sativa and M. piperita. Genetic influence on fatty acid profiles needs further studies.

Keywords: aromatic plants, eggshell color, fatty acid profiles, free-range system, laying hen