Optimizing a novel laser enrichment device for broilers: Evaluating an 8-minute exposure four times daily on broiler...

Increasing environmental complexity using a laser device (4 minutes duration, 4 times/day) has previously been found to improve voluntary broiler activity, locomotion, and bone quality without compromising growth performance or welfare indicators. Understanding the optimal duration for the laser device would maximize benefit for both the bird and producer. Therefore, the study objectives were to assess an increased laser duration of 8-min period occurring 4 times daily on Ross 708 growth performance, bird walking distance behavior, and tibia quality. Ross 708 broilers (n = 1,360) were randomly assigned to laser enrichment (8-min laser periods 4 times daily) or control (no laser enrichment) for 7-wk. On d 0, 70 focal birds were randomly selected for weekly gait and contact dermatitis scoring, and behavioral analysis. Focal bird walking distance was analyzed d 0-8 and 1 d/wk through wk 7. The right tibia was collected from all focal birds for dual-energy x-ray absorptiometry and bone breaking strength analyses on d 49. Data were analyzed using mixed linear models with pen nested within enrichment as a random effect (PROC MIXED), while walking distance data were analyzed using negative binomial generalized linear mixed models to account for overdispersion (PROC GLIMMIX, SAS 9.4). Enrichment did not impact feed intake, weight gain, or body weight across production phases (P > 0.05). Feed conversion ratio was increased 3 points in laser-enriched birds during the starter period (P = 0.01) but did not differ thereafter. Laser-enriched birds walked significantly further than controls during d 0-8 (40.3 cm, P = 0.03). No differences were observed in gait score, contact dermatitis, or air and litter quality. Laser-enriched birds had significantly greater tibia bone mineral density by 11.1% at d 49 compared with control birds (P = 0.04). These findings suggest that the laser enrichment continued to support favorable effects on broiler walking distance activity and bone mineral density, without adversely affecting growth performance or welfare outcomes.