Global poultry production has increased rapidly over the last 50 years and is now the most-consumed meat species in the world. The consumption of poultry in Poland accounts for almost 40% of the total meat consumption and averages 30 kg per person. Being the most flourishing sector of agriculture, poultry production faces many challenges from increasing competition (high quality products and lower prices for consumers). The profitability of poultry breeding and rearing is determined by the production of healthy and well-developed chicks, and the value of hatching eggs is closely linked to genetic line, flock age, layer housing conditions and parent flock nutrition, as well as incubation and pre- and post-hatching management. The qualitative assessment of newly hatched chicks must be based on clear and objective methods regarding health status of the flock and performance of the birds. It is essential that modern poultry production pays particular attention to these factors to achieve a high percentage of hatchability and the production of chicks which fully express their genetic potential under intensive production systems.

The paper addresses all feasible applications of long ahemeral light cycles in breeding flocks and reviews the limited published studies. Long cycles are likely to be most beneficial towards the end of the production cycle – when eggshell quality is often poor – and at the beginning of lay to increase the proportion of eggs exceeding the minimum weight for incubation. Published reports show an improvement in both fertility and hatchability of breeding flocks under long cycles.