Egg quality traits differ in hens selected for high as compared with low antibody response to sheep red blood cells

White Leghorn chickens were selected for 36 generations for high (HAS) or low (LAS) antibody response to SRBC 5 d after an intravenous challenge. Our objective was to determine differences in egg quality resulting from that selection. In total, eggs from 45 hens from each line were assessed for shape index (SI), weight (WT, g), albumen height (AH, mm), Haugh units (HU), yolk color (YC), and eggshell weight (ESW, g) and thickness (EST, mm). Three cycles representing early, middle, and late stages of production were examined. Eggs from HAS hens had higher SI scores (4.12 ± 0.55; P < 0.001) and greater AH (0.27 ± 0.12; P < 0.001) and HU (1.89 ± 0.91; P = 0.04) than LAS hens; conversely, eggs from LAS hens had greater EST (0.03 ± 0.01 g; P < 0.001) and heavier ESW (0.66 ± 0.09 g; P < 0.001) than HAS hens. Lines were similar for WT and YC (P > 0.52). Albumen height and HU decreased (P < 0.001), whereas WT, ESW, and EST increased (P < 0.001) over cycles for both lines. However, SI decreased in LAS hens, yet increased in HAS hens, across cycles (P < 0.001). An interaction between line and cycle was observed in WT, SI, ESW, and EST (P < 0.001), but only for WT did the interaction cause re-ranking across cycles. Egg quality was, generally, superior in HAS compared with LAS hens, suggesting that higher antibody response may maintain overall fitness.