Relationship of Egg Position During Incubation on Early Embryonic Growth and Hatching of Broiler Breeder Eggs

Four experiments, using broiler type eggs, were conducted to study the effect of egg position during incubation on early embryonic growth and hatching. Eggs were either incubated small end up (SEU), small end down (SED), or horizontal (FLAT). Results demonstrated that eggs in the FLAT position exhibited consistently heavier embryos and more embryos with the pipping tooth (7 days) than the other incubation positions. In contrast, eggs incubated in the SEU position exhibited consistently smaller chick weights, greater total mortality, lower hatchability, lower total pips, and greater chick wetness than the other treatments. Chicks from eggs in the FLAT and the SEU incubation positions required significantly less time to exhibit initial pips. However, they required significantly longer to emerge from the shell and had a significantly greater number of initial pips away from the air cell. This study demonstrated that die FLAT egg position resulted in the greatest embryonic development during the early stages of incubation but produced no advantage over the other egg positions at hatch.