Effects of particle size and feed form on the performance, egg quality, digestive organs and plumage condition in laying hens.

This study was conducted to investigate the effects of particle size and feed form on the performance, egg quality, digestive organs, and plumage condition in laying hens between 44 and 60 weeks of age. A total of 432 Hy-Line W80 white laying hens at 44 weeks of age were randomly allocated to 6 treatments with 12 replicates. Two particle sizes (fine and coarse; 3- and 9-mm screens, respectively) and three feed forms (mash, pellet and crumble), were evaluated in a completely randomized block design with a 2 × 3 factorial arrangement of treatments. Neither particle size nor feed form significantly affected final body weight (60 weeks), mortality rate or egg production (P > 0.05). Mash feed significantly increased average daily feed intake compared to pellets and crumbles when the particle size was coarse (P ≤ 0.05). Coarse particle size and crumble or pellet feeds improved feed conversion ratio and egg mass compared with the fine and mash treatments (P ≤ 0.05). Fine feed particle size improved shell quality and Haugh unit (P ≤ 0.05) compared to coarse grinding, while yolk color was lower (P ≤ 0.05) with the fine particle size. Shell quality and yolk color were reduced (P ≤ 0.05) in the pellet feeds. However, shell quality did not differ significantly from the mash feed in terms of shell breaking strength (P > 0.05), and yolk color did not differ significantly from the crumble feed (P > 0.05). Coarse and mash feeds significantly increased the relative weight of the gizzard (P ≤ 0.05). Neither particle size nor feed form affected plumage condition, except for neck feathers (P > 0.05). Overall, the results of the current research showed that crumble or pellet form and coarse particle size, rather than mash, and fine particle size, improved performance. In addition, the crumble feed form did not cause any significant compromise in egg quality while improving performance.