Laser Enrichment Device Stimulates Broiler Laser-Following Behavior While Increasing Individual Bird Locomotion and Pen-Wide Movement

Abstract

Genetic selection for fast growth rate and high breast muscle yield in modern broilers has unintended effects on animal welfare and behavior, namely in terms of inactivity and leg disorders. We hypothesized that exercise stimulated through environmental enrichment could positively stimulate pen-wide activity and improve bird welfare. The study objectives were to implement a laser enrichment device to motivate active and feeding behaviors throughout the pen. Twelve hundred Ross 708 broilers were randomly assigned to enrichment (LASER; laser enrichment, or CON; no laser enrichment) for 49 d. Seventy focal birds were randomly assigned to 14 video-recorded pens for behavioral analysis, including focal bird home pen behavior and walking distance. Pen-wide activity was also measured during the 4-min laser periods, four times daily, d0–8, and 1 day weekly, wk 1–6. Focal birds were gait scored wk 1–6, and were euthanized on d42 for tibia bone mineral content, density, and bone breaking strength analysis. Time spent active was increased in LASER-enriched birds compared to CON on wk 3–5 by up to 214% (wk 4), and percent of time at the feeder was increased in LASER-enriched birds by 761% on wk 4 (P < 0.05). Peak percent of birds following the laser (LASER-enriched pens only) was observed on d0 (8.52%). Over wk 1–6, peak laser-following behavior was observed on wk 3 (3.07% of birds). Percent of birds moving during laser periods was increased in LASER-enriched pens on d0, 1, 2, 6, 7, and 8, with a percent increase of 68.7% observed on d1 (P < 0.05). Percent of birds moving (laser-following or not) was increased on wk 1, 3, and 4 in LASER-enriched pens, with an increase of 69.7% observed on wk 4 (P < 0.05). No differences were found in tibia measures. These data indicate that laser enrichment stimulated voluntary locomotion through wk 5 and laser-following behavior through wk 6, and that the relatively small percent of birds actively following the laser stimulated pen-wide movement above the level of the CON through wk 4 on study.

Laser Environmental Enrichment and Spirulina Algae Improve Broiler Growth Performance and Alter Myogenic Gene Expression and pectoralis major Dimensions

“…This differs from the current results, where MSTN expression was positively increased with breast muscle width and body weight (breast filet weight unaffected by laser enrichment). Differences in both myogenic growth potential measured through mRNA expression as well as changes in macroscopic texture to the breast tissue observed here are likely due to laser-induced exercise (Meyer et al, 2021). Dietary algae did not impact breast width nor weight, apart from a notable exception at the 7-wk slaughter timepoint.…”

“…Ross 708 broilers (Aviagen, 2019a) have lower estimated body weight and FCR at d42 compared to Ross 308 (Aviagen, 2019b), as well as different estimated weight gain curves, which could certainly have impacted production outcomes. However, the improved growth performance across both studies and two genetic lines in LASER-enriched birds is a notable, consistent outcome that may be considered unexpected due to the increased exercise, attributed to innate foraging behavior, observed in both trials (Meyer et al, 2020(Meyer et al, , 2021.…”

“…A major concern with the WB phenotype is lack of adequate blood supply due to muscle fiber breakdown, and a resulting lack of oxygen leading to metabolically starved tissue (Pampouille and C. Hennequet-Antier, 2019;Velleman, 2019;Baldi et al, 2020). Hence, movement motivated by laser enrichment described in the companion work (Meyer et al, 2021) may have helped to improve breast meat quality and reduce WB severity by stimulating more healthy muscle growth and circulation. This is evidenced by the reduction in WB scores due to laser enrichment.…”

Breast muscle white striping and serum corticosterone reduced in broilers exposed to laser environmental enrichment

“…The authors summarized that forcing exercise in fast-growing broilers induces oxidative stress and negatively impacts animal welfare, but meat quality outcomes were not collected. Previous work by the current authors utilizing a visual form of environmental enrichment for broilers, a laser device activated 4 times daily for 4-min periods, increased voluntary physical activity, significantly increased breast muscle width, and numerically reduced WB score at 6 and 7 wk of age compared to the control without negatively impacting animal welfare outcomes ( Meyer et al, 2021a , b ). However, these studies did not include lab-based measurements of meat quality, an analysis of WS prevalence, or serum biomarkers of muscle damage and stress.…”

“…Focal birds ( n = 70) were gait scored weekly using methods previously described by the current authors ( Meyer at al., 2021a ). The same researcher conducted all gait scores.…”