Farm Environmental Enrichments Improve the Welfare of Layer Chicks and Pullets: A Comprehensive Review.

Simple Summary: Layer industries that are still using cage housing systems should encourage the provision of appropriate farm enrichments, especially at an early stage. Farm environmental enrichments such as litter, sand, alfalfa bales, chick papers, pecking stones, pecking strings, perches, slopes, elevated platforms, aviaries and outdoor access reduce feather and skin damage, as well as abdominal fat content. Additionally, they promote the development of the brain and musculoskeletal systems and improve biological function, productivity and product quality with lifelong benefits for hens by continuously exposing them to free access to forage, dust baths and free locomotion. In this review, we summarize several common and effective methods of farm environmental enrichments, including different manipulable materials, structural equipment, and outdoor access, moreover, the competence of the farm staff is a requirement to achieve useful utilization of these farm environmental enrichments that aim to reduce stress and improve the welfare and productivity of layers. Proper farm environmental enrichments benefit the wellbeing of caged birds. Currently, cage housing is regarded as a global mainstream production system for laying hens. However, limited living space and confinement of birds in cages cause welfare and health problems, such as feather pecking, osteoporosis, obesity, and premature aging. Many studies have been conducted to alleviate layer welfare problems by providing farm environmental enrichments such as litter, sand, alfalfa bales, chick papers, pecking stones, pecking strings, perches, slopes, elevated platforms, aviaries and outdoor access with a trend towards complex enrichments. The provision of appropriate enrichments continuously attracts layers towards pecking, foraging, dust bathing, and locomotion, thereby giving lifelong benefits to laying hens. Hence, raising chicks and pullets under such conditions may reduce feather and skin damage, as well as accumulation of abdominal fat, and improve several biological features such as health, productivity, quality products, and docility of laying hens. Therefore, providing enrichment during the first few days of the layer's life without any interruption is crucial. In addition, due to different farm conditions, environmental enrichment should be managed by well-trained farm staff. For example, in preventing feather pecking among the birds, litter materials for foraging are superior to dust bath materials or new items. However, a limited supply of litter creates competition and challenges among birds. Therefore, providing farm environmental enrichment for layers requires proper handling, especially in commercial layer farms. Hence, improving the welfare of chicks and pullets through optimizing on-farm environmental enrichments is essential for production systems practicing cage housing. [ABSTRACT FROM AUTHOR]