Figure 4.

Effect of edible enrichment materials on the income over feed and enrichment costs in brown-egg and white-egg layer hens during the laying period (weeks of age 21–48). Boxplots indicate the data range as well as median, and lower and upper quartiles. Different indices indicate differences between variants (P < 0.05). Abbreviations: IOFEC, income over feed and enrichment costs; variants: V1, no additional enrichment materials supplied over the whole study period; V2, the rearing period with and the laying period without supply of additional enrichment materials; V3, the rearing period without and the laying period with supply of additional enrichment materials; V4, supply of additional enrichment materials over the whole study period.