Observations on the embryonic development of domestic meat-type guinea fowl (Numida meleagris)

Guinea fowl breeding for meat production is widespread across Europe and the USA. For hatcheries to achieve their output potentials, they need in-depth knowledge about incubation techniques and guinea fowl embryonic development. The aim of this study was to provide updated quantitative data on the developing meat-type strain embryo and to describe its embryonic growth pattern in terms of embryonic weight modelled using Gompertz and logistic functions. Eggs from a 56-week-old genetically controlled flock (Galor S.A.S., Amboise, France) were individually weighed and incubated according to good hatchery practices. 10 embryos were randomly removed every 12 h through to hour 192 of incubation, and thereafter every 24 h. Incubation traits, blastoderm diameter, vitelline circulation diameter, and embryo body weight were recorded, and the mean daily wet embryo-specific mass was calculated. During each session, photographic documentation of the embryos was also obtained, including a general view of the egg content as well as the isolated embryonic body. Embryonic growth curves were estimated using Gompertz and logistic functions, and their parameters are given. High fertility (96%) and hatchability (81%) rates were observed, and the mean keet weight was 32 g at hatch. The accuracy of the curve fit was high for both models. The curves' inflection points occurred on days 21 and 23 for the logistic and Gompertz models, respectively, demonstrating an embryonic growth pattern typical of a precocial bird species. A photographic chart of the in-ovo chronological development of guinea fowl is provided.