Breeder age influences embryogenesis in broiler hatching eggs

The effects of dietary fat and. broiler breeder age on egg and embryo chara cteristics during incubation were investigated. Breeders were fed diets con taining no added fat or 3.0% added poultry fat (PF) for peak energy intakes of 430 and 467 kcal/hen day (pC/ d), or 1.5% PF or 3.0% corn oil at 449 pC /d. Feeding of diets was initiated at 22 wk, and eggs were collected for in cubation at 27 and 36 wk of age. Percentage incubational egg weight loss wa s determined between day of set and Days 6, 12, and 18. Percentage wet and dry embryo weights, embryo moisture content, and eggshell weights were dete rmined at 6, 12, and 18 d of incubation. Percentage yolk sac weight and wet and dry Liver weights and moisture content were determined on Days 12 and 18. Percentage gall bladder weight was determined on Day 18. There were no observed effects due to breeder diet. However, eggshell weight at Days 6, 1 2, and 18 was higher in 27-wk-old hens compared with 36-wk-old hens. Conver sely, egg weight loss between Day 0 and Days 6, 12, and 18 and yolk sac wei ght across Days 12 and 18 of incubation were lower in eggs at 27 wk of age compared with 36 wk. At Day 18, dry embryo weight was higher and wet liver weight was lower at 27 wk compared with 36 wk. A slower rate of DM accumula tion in embryos at Week 36 compared to Week 27 was associated with increase d incubational water loss and decreased embryo moisture content, eggshell p ercentage, and yolk sac absorption rate. These data demonstrate that change s in eggshell characteristics with broiler breeder age can alone impact yol k uptake, growth, and body composition in subsequent embryos.