Effects of Hydroponic Barley Green Fodder Supplementation on Egg Quality and Proximate Composition in ATAK-S, Lohmann Brown, and Leghorn Laying Hens

Abstract

Hydroponic barley green fodder (HBGF) is increasingly discussed as a low-input, locally producible feed resource for poultry. This study examined how HBGF supplementation affects egg quality traits and the proximate composition of egg white and yolk in three laying-hen genotypes (ATAK-S, Lohmann Brown, and Leghorn) over a 42 day feeding period under free-range conditions. Hens of each genotype were allocated to a control group fed a commercial layer diet and to a group receiving the same feed plus fresh HBGF ad libitum. Egg weight, yolk, albumen, and eggshell percentages, eggshell thickness, egg shape index, yolk color, yolk index, albumen index, and Haugh unit were recorded on days 0, 21, and 42, and the dry matter, crude protein, crude fat, and ash contents of egg white and yolk were determined. Genotype was the primary contributor to variation in egg weight, egg shape index, and albumen index on every sampling day, in Haugh unit on days 0 and 21, in yolk percentage from day 21, and in albumen percentage on day 42 (p < 0.05–0.001). ATAK-S hens produced the heaviest eggs, Lohmann Brown hens had the greatest albumen percentage and egg shape index, and both ATAK-S and Leghorn hens had higher yolk percentage compared to Lohmann Brown. Albumen index and Haugh unit were higher in Lohmann Brown and Leghorn compared to ATAK-S. Eggshell thickness, eggshell percentage, yolk color, and yolk index did not differ among genotypes during the feeding period, apart from a genotype effect on yolk index on day 21 only. HBGF supplementation did not change any physical egg quality trait, including yolk color and yolk index, on day 21 or day 42 (p > 0.05). The proximate composition was mainly affected by the egg percentages (white versus yolk), with the yolk possessing significantly higher levels of dry matter, protein, fat, and ash contents compared to the white. HBGF produced compositional alterations that were both genotype and time dependent, with elevated albumen protein in ATAK-S and Lohmann Brown on day 21, increased yolk fat in ATAK-S and Lohmann Brown but decreased yolk fat in Leghorn, and no consistent change in albumen ash; however, these alterations varied among genotypes. Overall, genotype rather than HBGF influenced egg quality; however, HBGF produced slight changes in some compositional characteristics which tend to be genotype-specific rather than general improvements in egg quality.