Defatted or hydrolyzed black soldier fly larvae have sufficient potential as an alternative to fishmeal for weaned pigs

This study was conducted to investigate the effects of defatted and hydrolyzed forms of black soldier fly larvae (Hermetia illucens; BSFL) as fishmeal substitutes in the diet of weaned pigs. In Experiment 1, a total of seventy-two 4-week-old crossbred weanling pigs [Duroc × (Landrace × Yorkshire)] with an initial body weight (BW) of 9.39 ± 1.02kg were used. Each treatment had 6 replicate pens, and 3 pigs were assigned to each pen. In Experiment 2, a total of twenty-four 4-week-old crossbred weanling pigs [Duroc × (Landrace × Yorkshire)] with an initial BW of 9.24 ± 1.01kg were used. There was one pig treatment in a cage and eight replicate cages per treatment. The three treatments were as follows: a basal diet containing 30g/kg fish meal (CON), a basal diet without fishmeal and substituted with 30g/kg defatted BSFL powder (T1), and a basal diet without fishmeal and substituted with 30g/kg hydrolyzed BSFL powder (T2). Experiments 1 and 2 were conducted over a six-week period. In Experiment 1, there were no differences among the treatment groups in growth performance. At 2 weeks, the apparent total tract digestibility (ATTD) of crude protein (CP) was significantly higher (P < 0.05) for the CON and T1 groups compared to the T2 group. For ATTD of gross energy (GE) at 6 weeks, the T1 group tended to be higher (P = 0.095) than the T2 group. In Experiment 2, at 2 weeks, the ATTD of dry matter (DM) was significantly higher (P < 0.05) in the T2 group than in the CON and T1 groups. At 6 weeks, the T2 group showed significantly higher (P < 0.05) ATTD of DM and GE than the CON and T1 groups. At 2 weeks, the Escherichia coli count in the T2 group was significantly lower (P < 0.05) than that of the CON and T1 groups. In conclusion, it was found that the defatted and hydrolyzed BSFL as a substitute for fishmeal did not negatively affect growth performance. Also, the defatted and hydrolyzed BSFL could improve nutrient digestibility and Lactobacillus counts. Therefore, it is considered that defatted or hydrolyzed BSFL has the potential to replace at least 30g/kg fishmeal in weaned pig diets.