Behavior and production responses of pullets and laying hens to enriched housing and lighting
The global demand for egg-source protein has been increasing rapidly along with the mounting public concerns over laying hen welfare. As a result, alternative hen housing has been emerging and adopted in different parts of the world, especially in developed countries. This dissertation had the overarching goal of generating the much-needed knowledge related to alternative laying hen housing design and management for improved laying hen welfare, efficiency of resource utilization, and production performance. Supporting this overarching goal were two primary research objectives that aimed to quantify behavioral and production performance responses of pullets and laying hens to perch design/configuration and light type/source. Toward that end, this dissertation covered five experiments that were conducted in controlled environment, aiming to supplement the existing knowledge base for the perches and lighting used in egg production systems. Each experiment aimed to fulfill a specific set of objectives, including: 1) examine perch-shape preference by laying hens and characterize temporal perching behavior of novice hens (no prior perching experience) after transfer from pullet-rearing cage to enriched colony setting (Chapter 2), 2) validate the suitability of the existing perch guideline on the minimum horizontal space requirement between parallel perches for laying hens (Chapter 3), 3) quantify the performance of a poultry-specific LED light vs. a warm-white fluorescent light with regards to their effects on pullet growing performance, activity levels, and welfare (Chapter 4), 4) investigate light preference of pullets and laying hens between a poultry-specific LED light vs. a warm-white fluorescent light, and evaluate the potential influence of prior lighting experience of birds on their subsequent preference for light (Chapter 5), and 5) evaluate the effect of light exposure of a poultry-specific LED light vs. a warm-white fluorescent light during rearing or laying phase on timing of sexual maturity, egg production performance, egg quality, and egg yolk cholesterol content of laying hens (Chapter 6).
The main findings from the experiments covered in this dissertation are as follows. The novice young hens showed increasing use of perches over time, taking them up to 5-6 weeks of perch exposure to approach stabilization of perching behaviors in the enrich colony setting; and the birds showed no preference for the perch shape of round or hexagon (Chapter 2). The horizontal distance of 25 cm between parallel perches was shown to be the lower threshold to accommodate the hen’s perching behaviors (Chapter 3). The poultry-specific LED light and the fluorescent light yielded comparable growing performance, livability, and feather conditions of W-36 pullets during the rearing phase, but the poultry-specific LED light showed more stimulating effect on the pullet activity levels (Chapter 4). Pullets and laying hens exhibited a somewhat stronger choice for the fluorescent light as compared to the poultry-specific LED light, regardless of prior lighting experience; however, this tendency did not translate to differences in the proportion of feed use under each light type (Chapter 5). The poultry-specific LED lights yielded comparable production performance and egg quality of W-36 laying hens to the fluorescent lights (Chapter 6). Results from this dissertation research are expected to contribute to a) scientific information on laying hen perch design and placement and responses of novice birds to perch introduction, b) scientific evidence for setting or refining guidelines on horizontal distance of perches for laying hens in alternative hen-housing systems, and c) decision-making in selection of lighting type or source for efficient pullet rearing and egg production. The research also identified areas that may be considered in the future studies.