Vitagenes in poultry production: Part 1. Technological and environmental stresses

Commercial poultry production is associated with various stresses affecting productive and reproductive performance of birds and their health status. In general, there are four major types of stress in poultry industry: technological, environmental, nutritional and internal stresses. This review considered main technological stresses: chick placement, increased stocking density, chicken weighing, grading and group formation in rearing houses, as well as bird transferring to breeder houses. The following paper analysed consequences of such environmental stresses as temperature stress and high levels of dust and ammonia in poultry houses. It has been proven that most of the aforementioned stresses suppress reproductive performance of parent birds, including reduced fertility and hatchability. Furthermore, stresses are associated with impaired feed conversion, reduced average daily weight gain, immunosuppression and increased mortality in growing birds. A growing body of evidence indicates that most of stresses in poultry production at the cellular level are associated with oxidative stress due to excess of free radical production or inadequate antioxidant protection. Therefore, the development of the effective nutritional solutions to decrease negative consequences of commercially-relevant stresses is an important task for poultry scientists. One of such approaches is based on vitagene concept which will be considered in the second part of the review.