Яйцекладка-сложный процесс, в котором время яйцекладки (ВЯ), цикл яйцекладки (ЦЯ) и интервал яйцекладки (ИЯ) взаимообусловлены (B.G. Roy с соавт. 2014). Настоящий обзор посвящен оценке влияния освещения на время яйцекладки и его связи с показателями качества яиц и продуктивностью кур (Gallus gallus domsticus L.). ВЯ напрямую сопряжено со временем овуляции, которое, в свою очередь, зависит от времени пикового выброса лютеинизирующего гормона в кровь передним отделом гипофиза (S.C. Wilson с соавт., 1984). В стандартных 24-часовых свето-темновых циклах при однократном чередовании света и темноты яйцекладка происходит в основном за световой период (F. Noddegaard, 1998; Г.А. Кирдяшкина с соавт. 2009), а при режимах прерывистого освещения ассиметричного типа-в течение «субъективного дня» (

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In hot-climate regions high ambient temperature is one of the main problems of poultry farming. It is a reason for large financial losses caused by a significant decrease in the livability and productivity of poultry and the quality of products. Poor shell quality results in increased egg breakage and cracking. Such eggs lose the abilities for long-term storage or incubation and their market price is become significantly (1.5-3-fold) reduced. In the review presented the biological role of the eggshell, certain aspects of its formation, and the main reasons for the deterioration of eggshell quality in high ambient temperatures are discussed. It was shown that the eggshell quality depends on the genotype, age, feeding, health status, management conditions, etc. High ambient temperatures (above 32-35 °C) disrupt the process of eggshell formation and leads to a significant decrease in its weight, thickness, and strength. The negative impact of high ambient temperature on eggshell quality is associated with a complex set of problems, including low feed intake by hens, acid-base and mineral imbalances, physiological disorders in the endocrine system and other organs and mechanisms involved in the process of eggshell formation. The understanding of these reasons gives an opportunity for the development and implementation of targeted interventions and enables the minimization of negative impact of heat stress on eggshell quality and the efficiency of the commercial egg production.