Feed restriction in Broiler Breeders: A systematic review of impact on productive performance, reproductive outcomes, and welfare indicators
Abstract
Feed restriction is indispensable to the management of broiler breeder flocks (Gallus gallus domesticus). In the absence of rationing, these birds exhibit abnormal obesity, reproductive dysfunctions, and elevated mortality. Despite five decades of experimental production, no systematic synthesis had simultaneously evaluated the effects of different restriction strategies on productive and reproductive performances and on breeder welfare. This systematic review was conducted to address this gap and drew upon articles published in the Scopus and Web of Science databases between 1989 and 2025. Study selection, carried out via Rayyan, and risk-of-bias assessment using the SYRCLE tool yielded a final corpus of 90 studies.
According to the authors, ad libitum feeding is deleterious, as it disrupts the ovarian follicular hierarchy and reduces fertile egg production by approximately 40 units per hen. Every-day feeding (ED) surpasses skip-a-day feeding (SAD) in terms of body weight uniformity, feed efficiency, eggshell quality, and hatchability, with systematically lower corticosterone levels. Furthermore, maintaining SAD after photostimulation induces lasting reproductive dysfunctions and a net loss of at least 17 eggs per hen. Dilution with insoluble fibre reduces stereotypies and improves clinical welfare indicators (plumage quality, foot lesions, fault bars, etc.) without altering the hypothalamic expression of appetite-regulating peptides (AGRP, POMC). Precision feeding improves body weight uniformity but significantly reduces egg production. As a synthesis, this study reveals that daily feed restriction remains the best-supported programme for jointly optimising productive and reproductive performances. Qualitative restriction improves clinical welfare indicators without resolving metabolic hunger. However, no currently available strategy demonstrates a simultaneous and robust benefit across all three domains investigated.
