Impact of preincubation on temporal hatching distribution and traits of egg structures in common pheasant

The temporal distribution of hatching is an important factor affecting chick uniformity, welfare, and hatchery efficiency. Although preincubation has been successfully applied in several poultry species to improve hatchability and synchronise embryonic development, its effects on embryogenesis and hatch timing in pheasants remain poorly understood. The aim of the study was to evaluate the effect of pheasant egg preincubation on the temporal distribution of hatching and the course of embryogenesis, with particular emphasis on changes occurring in extraembryonic structures. The research involved 700 hatching eggs, which were divided into a control group (CON) and an experimental group (PRE), in which a preincubation protocol was applied consisting of 6 h of incubation (37.7 °C), 12 h of standard storage (17 °C ± 0.5 °C), 12 h of incubation (37.7 °C), and 6 h of standard storage (17 °C ± 0.5 °C). Eggs from the CON group were stored at 17 °C ± 0.5 °C during this time. Analyses included fresh egg quality, egg weight loss during incubation, incubation time, hatching parameters, chick quality, and the physicochemical properties of the eggshell, albumen, amniotic fluid, and yolk contents. The application of preincubation significantly shortened incubation time in the PRE group, where 87% of chicks hatched as early as 567 h of incubation. In the CON group, the hatching process was markedly prolonged and more temporally dispersed. The proportion of unhatched chicks was significantly lower in the preincubated group (P = 0.046). No differences were observed in egg weight loss or chick quality (P > 0.05). Eggshell thickness and the pH of albumen, yolk, and amniotic fluid changed during incubation. Significant differences in copper and manganese content were observed between groups (P = 0.047; P = 0.029), and differences in iron, zinc, and manganese content depending on the day of incubation (P < 0.001; P = 0.009; P = 0.017). Moreover, significantly higher lysozyme activity in the amniotic fluid was recorded on day 14 of incubation in the PRE group, which indicated enhancement of the developing embryo's natural antimicrobial barrier (P = 0.001). It can be concluded that preincubation is an effective method for shortening incubation time in pheasants without negatively affecting chick quality. The observed changes in extraembryonic structures and lysozyme activity suggest that preincubation may also influence physiological processes associated with embryonic development.