Effects of Incubation Light on Behaviour, Growth Performance, Blood Parameters, and Digestive Enzymes in Post-Hatch Layer Chicks

In commercial hatcheries, chicken embryos are incubated in complete darkness. However, in a natural environment, chicken embryos receive light stimulation during the incubation process as hens need to leave the nest to feed or turn the eggs. Therefore, providing light during incubation is closer to the natural growth environment of chicken embryos, which may have a positive effect on their growth and development. This study investigated the effects of providing different wavelengths of light during incubation on the behaviour, growth, immunity, and stress responses of post-hatch chicks. The results indicated that providing white light during incubation may enhance the growth performance of post-hatch chicks and potentially improve their ability to cope with environmental changes. This study aims to determine the effects of light exposure during incubation on the growth and development of post-hatch chicks and to provide a basis for the development of effective lighting strategies during the incubation period. Manipulation of light during incubation may have an effect on post-hatch chicks through the role of prenatal stage. The effects of providing different wavelengths of light (white, blue, and green lights, dark as control) during incubation on the growth performance, organ development, immune response, stress related hormones, digestive enzymes and behaviour of post-hatch chicks were investigated for 1-42 days. A total of 60 chicks per light treatment in three batches were used in this study. The results showed that the percentage of chicks accessing to feed and water resources appeared not to be affected by incubation light. Chicks hatched under white light were found to have a growth advantage (p < 0.05). The weight of organs (except thymus), IgA, IgY, IgM and heterophil to lymphocyte (H/L) ratio for post-hatch chicks were not affected by incubation light (p > 0.05). Thymus weight was reduced in chicks incubated under blue light compared to dark incubation (p < 0.05). The jejunum amylase and ileum lipase activities were significantly affected by the light treatments (p < 0.01). All light incubation chicks had stable plasma corticosterone levels and may have better ability to cope with environmental changes. Hence, white light photoperiod incubation may have potential to improve post-hatch chicks' growth performance and environmental adaptability.