Double-yolked (DY) and single-yolked (SY) duck eggs (n = 1318 for both) were candled and weighed on Days (d) 2, 8, 12, 15, 19, 22 and 25 of incubation and yolk/embryo position was recorded on d2, d8 and at post-mortem. From d8 only eggs with live fertile yolk(s) remained in the incubator. On d2, 99.39% of yolks in DY eggs were in the adjacent position and by d8 yolk positions changed to paralle...