The influence of egg sequence position on fertility, embryo viability, and embryo weight in broiler breeders

A study was undertaken to determine whether fertility, early embryo viability, and the weight of the egg, shell and embryo are influenced by the position of an egg in a laying sequence. One hundred and three Indian River broiler breeder hens were housed individually in cages at 21 wk of age. Beginning at 43 wk of age, each hen was inseminated once per week, with 50 microliter of fresh undiluted pooled semen from Indian River broiler breeder males. Beginning at 45 wk of age, and for the following 45 days, all eggs laid were collected. Eggs were collected hourly for 8 h after "lights on" and a final daily collection was made 14 h after lights on. Each egg was classified as "first-of-sequence" or "subsequent". Eggs were weighed and placed in a forced-air incubator twice per week. After 168 h of incubation, the eggs were removed from the incubator, weighed and assessed for fertility and embryo viability status. The embryo was also weighed. Shell weight was recorded after 3 to 4 days of air drying. Egg weight was significantly greater in first-of-sequence compared with subsequent eggs. First-of-sequence eggs exhibited significantly smaller Day 7 embryos (on a percentage basis), lower shell weight (on a percentage basis), and significantly less egg weight loss during the 7 day incubation period (absolute and percentage basis) than did subsequent eggs of a sequence. Least squares (LS) means for fertility did not differ significantly between first (87.02%) and subsequent (89.56%) eggs. There was no significant difference in LS means for embryo viability (number viable per 100 fertile eggs set X 100) between first (89.71%) and subsequent (92.75%) eggs. However, the number of viable embryos per 100 eggs set (fertility X viability) was significantly lower in first (78.74%) compared with subsequent (83.17%) eggs.