207 Impacts of beak trimming and dietary fiber on welfare and productivity of laying hens

Abstract

Abstract Beak trimming is a routine management practice in the egg industry to reduce damage caused by injurious pecking; however, it raises welfare concerns including pain and sensory loss. Dietary manipulation may be a feasible and welfare-friendly alternative to beak trimming in laying hens. Here, we hypothesized that dietary inclusion of insoluble fiber (chitin) throughout the starter and grower periods would result in improved welfare and productivity in both beak-trimmed and beak-intact chickens. One-day old female Hy-Line Browns (n = 192) were randomly assigned to one of four treatments in a 2 X 2 factorial design (n = 4 pens/treatment; 12 birds/pen): birds were infrared beak-trimmed or had their beaks left intact and were fed one of two diets (standard vs. 2% chitin) for 8 wk. Birds were housed in floor pens containing litter and perches with ad libitum access to feed and water. Body weight and feed intake were recorded weekly. Beak sensitivity was assessed using a pressure transducer to measure pecking force weekly from 3 to 8 wk of age. A tonic immobility test was performed at 7 wk of age to measure fearfulness. Plasma corticosterone was determined using enzyme-immunoassay procedures at 8 wk of age. Data were analyzed with linear mixed models with beak condition and dietary treatment modeled as fixed effects, and pen and bird ID as random effects. Beak-trimmed birds fed the standard diet weighed less (P < 0.001) than all other groups throughout all growth stages, including starter 1 (0-3 wk), starter 2 (4 to 6 wk), and grower (7 to 8 wk; Table 1). Beak-intact birds fed 2% chitin had a greater feed intake and feed conversion ratio (P < 0.05) compared with other groups during the starter 2 and overall experimental period. Beak-trimmed birds exhibited weaker pecking force than beak-intact birds for the first 7 wk (P < 0.001; Table 2). Beak-trimmed birds fed 2% chitin had significantly less corticosterone (Figure 1) than birds fed the standard diet (P < 0.05), and a shorter tonic immobility duration than all other groups (P < 0.05). Dietary chitin was also associated with a shorter latency until the first alert head movement and a greater number of inductions of tonic immobility than the standard diet (P < 0.05), which suggests that insoluble fiber supplementation reduces fearfulness regardless of beak-condition status. Our results suggest infrared beak trimming increases beak sensitivity for several weeks, potentially resulting in decreased feed intake and body weight in the first 8 wk of life (Table 3). Dietary supplementation with chitin appears to offset the effects of beak trimming on growth, but not beak sensitivity, and may improve welfare in beak-trimmed and beak-intact birds by reducing stress responses. Future studies are needed to elucidate the different mechanisms behind the observed effects.