PSXIII-4 Effects of Keel Bone Fracture on Behavioral Fear Responses of Laying Hens in the Late Laying Period

Keel bone fracture (KBF) of laying hens has become one of the important welfare problems for health and production performance. The present study aimed to assess the fear responses in native breed of Lindian chickens and commercial Hyline Brown laying hens with and without KBF at the late laying period. At their 56-week-age, a total of 76 Hyline Brown hens and 80 Lindian hens selected from furnished cages were housed individually in battery cages. The laying hens were divided into normal group and keel fracture group. The fear tests, including tonic immobility tests (TI), open field tests (OFT), and startle reflex tests (SRT) were measured sequentially. The fractured laying hens from two breed had significant elevated duration time in the TI test than that of normal laying hens (P < 0.05). In OFT test, the number of grids, steps, and time spent in the outer ring of fractured Lindian hens were significantly less than those of normal hens (P < 0.05), and the time spent in the inner ring was significantly greater (P < 0.05). The movement latency and the time spent in the inner circle of fractured Hyline Brown hens were significantly greater than those of normal hens (P < 0.05), but the number of grids and steps passed and the time spent in the outer ring were significantly less than those of normal hens (P < 0.05). There was no significant difference in call latency and total call between fractured and normal hens of Lindian and Hyline Brown strain (P > 0.05). The total score of startle reflex of Lindian hens with keel fracture was significantly less than that of normal laying hens (P < 0.05). Therefore, keel fracture reduced the welfare of laying hens in the later stage of laying by affecting their behavioral fear responses.