Can black soldier fly live larvae improve postweaned piglets' welfare?

We tested the effects of black soldier fly (BSF) live larvae administration on some growth and welfare indicators of weaned piglets. Forty-eight piglets were distributed in pens of 6 and allotted either to control (C, kept in standard commercial conditions) or to live larvae group (LL, receiving 300-600g/pen/day of BSF LL as a supplement). The trial lasted 40 days. Growth parameters were recorded and behaviour was video recorded every 10 days. Body and tail lesions were assessed using the Welfare Quality protocol and hair cortisol was quantified as a chronic stress indicator. Data were submitted to ANOVA using the group as a fixed effect and the pig as a random effect. Average daily gain was 0.53 in C and 0.52 kg in LL, average lesion and tail scores were 0.58 and 0.12 in C, and 0.23 and 0.00 in LL (P>0.05). Video analysis showed that LL piglets spent 14% of the observed time interacting with larvae, reducing time spent at the feeder (16.6 vs. 21.9%, P<0.001), interacting (neutral interactions 5.1 vs. 8.7%, P<0.01; aggressive interactions 2.3 vs 3.5%, P<0.05), manipulating the enrichment (hanging wooden or chains, 1.2 vs. 2.3%, P<0.05) and biting the tail of their pen mates (0.0 vs. 0.5%, P<0.05) compared to C. Hair cortisol was tendentially lower in LL (8.1 vs.10.9 pg/mg, P=0.051). Pending more extensive behavioural observations, our results indicate that BSF LL administration can improve animal welfare by shifting the exploratory behaviour from the body of pen mates and pen equipment to larvae. No significant effect in terms of lesion score reduction was observed, but hair cortisol showed tendentially lower chronic stress levels. Supported by EU grant n°J83C22000830005–AGRITECH research programme.