The present review aims to describe the effects of space allowance and group size on the welfare of farm animals. Under proper conditions, animals must be able to maintain and use their space in order to meet their basic physiological, psychological and social needs. The importance of a proper use of space within production systems lies in its relationship with many aspects of the animal's environment, such as the design of facilities for feeding and resting, the number of animals present in the same housing and their social interactions, as well as the establishment of optimal microclimatic conditions. The space allowance represents a measure of the area offered according to the species? requirements and purpose, while group size refers to the optimal number of individuals that can be housed in a given space. Both are closely related to stocking density. Therefore, the provision of enriched, well‑sized housing facilities enhances welfare compared to small and monotonous ones. Finally, when designing these housing facilities, it is important to consider the behavior and animal production purpose of each species, as well as its physiological state, to train farmers in the use of appropriate management practices, from the animal welfare point of view.

Sánchez‑Casanova RE, Muñoz‑Osorio GA, Sarmiento‑Franco LA (2021). ¿Cómo afecta la disponibilidad de espacio y el tamaño de grupo al bienestar de los animales de granja?. ITEA‑Información Técnica Económica Agraria 117(4): 375‑389. https://doi.org/10.12706/itea.2020.041