Behavioural reactivity of slow-growing chickens fed live black soldier fly larvae: preliminary results

The aim of this preliminary research was to investigate the effects of access to black soldier fly (Hermetia illucens; HI) live larvae on fearfulness in slow-growing chickens. We hypothesized a positive effect of early experience and environmental enrichment on fear reduction. Eighty-four Nacked Neck (Red JA Nacked Neck – Hubbard®) slow-growing chickens were randomly allotted to 12 pens (1m×3m) at 14 days of age. Each pen was assigned to a dietary treatment (TRT; 4 pens/treatment, 7 chickens/pen) as follows: i) control diet (CO): commercial feed; ii) CO + 10% of the expected daily feed intake (DFI) of HI live larvae (g) (C10); iii) CO + 20% DFI of HI live larvae (g) (C20). The commercial diet was distributed ad libitum in all the treatments. The behavioural reactivity (fear response) was tested using the Novel Object Test (NOT). The novel object – a XXL RED KONG® Classic dog toy – was placed at about 1.5 m from the front wall of the rearing pen between the feeding ad drinking areas. The number of birds close (10 cm max distance) to the object was recorded every 30 sec for 2 min. The total number of birds close to the novel object in the observational time lapse was calculated (TOT). The birds were weighed after the test (WEI). NOT was repeated 1 h before (BEF) and 1 h after (AFT) larvae dietary supplementation at 4, 8, 12 weeks of age. Statistical analysis was carried out using the GLM procedure (SAS 9.4®); WEI and TOT were the dependent variables, while dietary treatments (C0, C10, C20), age of birds (4, 8, 12 wks.), testing moment (BEF, AFT) and their interactions were the sources of variation. WEI was significantly affected by TRT and age (physiological growth), TOT was affected only by ACC. In the overall period, C10 and C20 birds were slightly heavier than C0 birds, whereas body weight was similar in C10 and C20 birds (P 0.05). TOT was significantly affected by larvae supplementation, but no significant differences between C10 and C20 were recorded. The present results show how access to HI live larvae can reduce birds’ fearfulness improving their coping ability and welfare. Further studies are needed to confirm the positive effects of live larvae supplementation on birds’ behaviour and welfare in broiler rearing systems.