Effects of pen enrichment on leg health of fast and slower-growing broiler chickens

Abstract

Pen enrichment for broiler (meat-type) chickens is one of the potential strategies to stimulate locomotion and consequently contribute to leg health and welfare. This study was designed to evaluate effects of using a plethora of pen enrichments (barrier perches, angular ramps, horizontal platforms, large distance between feed and water and providing live Black Soldier fly larvae in a dustbathing area) on tibia characteristics, locomotion, leg health and home pen behaviour of fast and slower-growing broiler chickens. The experiment was set up as a 2 x 2 factorial arrangement with a total of 840 male broiler chickens in a complete randomized design (7 replicates per treatment and 30 chickens per replicate) with the following treatments: 1) pen enrichment (enriched pen or non-enriched pen); 2) broiler strain (fast-growing Ross 308 or slower-growing Hubbard JA 757). Home pen behaviour and use of enrichment were observed. At approximately 1400 and 2200 gram body weight, two chickens per pen were randomly selected and slaughtered, to investigate tibia morphological, biophysical and mechanical characteristics and leg health. Pen enrichment positively affected tibia biophysical characteristics, e.g., osseous volume (?=1.8 cm3, P=0.003), total volume (?=1.4 cm3, P=0.03) and volume fraction (?=0.02 %, P=0.002), in both fast and slower-growing chickens, suggesting that pen enrichment particularly affects ossification and mineralization mechanisms. Accordingly, locomotion and active behaviours were positively influenced by pen enrichment. However, pen enrichment resulted in lower body weight gain in both strains, which might be due to higher activity or lower feed intake as a result of difficulties of crossing the barrier perches. Regarding the strain, slower-growing chickens showed consistently more advanced tibia characteristics and more active behaviour than fast-growing chickens. It can be concluded that pen enrichment may lead to more activity and better bone development in both fast and slower-growing chickens.

Fly in the coop : How black soldier fly larvae improve broiler and pig welfare

“…Compared to lighter broilers, heavier broilers have a displaced centre of gravity that requires them to place their feet further apart to remain balanced, causing excessive pressure on the leg bones (Corr et al, 2003a). As a result the leg bones of heavy broilers are relatively short and light, and their low concentrations of calcium and phosphorus suggests they are also fragile (Corr et al, 2003b;Güz et al, 2021). Impaired leg development often results in leg health problems such as tibial dyschondroplasia or varus/valgus deformities that can cause varying degrees of lameness (Granquist et al, 2019;Shim et al, 2012).…”

“…Currently, we have many tools available to study animal behaviour and animal health. Behaviour can be assess through for example instantaneous scan sampling (Chapter 2-7) or automated video tracking (van der Zande et al, 2021), and health parameters can be scored by validated visual scoring systems (Butterworth, 2009;Pedersen and Toft, 2011) or biophysical and chemical analyses (Goodlad et al, 1991;Güz et al, 2021;Luo et al, 2020a). In contrast, there are limited tools available to study the affective state of an animal, especially concerning positive affective states.…”

“…For example, while slow-growing broilers experience fewer leg health problems than fast-growing broilers (Rayner et al, 2020) they still experience health problems and are housed in barren environments. A such, their behaviour and leg health could benefit from environmental enrichment (Güz et al, 2021). Other poultry may also benefit from BSFL provisioning.…”