Effects of dietary replacement of fish meal by defatted black soldier fly larvae on growth performance, blood profiles, immune response, and diarrhea incidence in weaning pigs.

Purpose: The purpose of this experiment was to evaluate the effects of dietary replacement of fish meal by black soldier fly (BSF) larvae on growth performance, blood profiles, immune response, and diarrhea incidence in weaning pigs.

Methods: A total of 160 weaning ([Yorkshire × Landrace]) × Duroc) pigs (7.47 ± 0.02 kg body weight [BW]) were assigned to four treatments based on sex and initial body weight, with five replicates of eight pigs per pen in a randomized complete block design (RCBD). Experimental diets with black soldier fly (BSF) larvae replaced fish meal (FM) at 0, 25, 50, and 100% for phase I (0 to 2 weeks). Phase II (3 to 4 weeks) were as follows: 1) Control: corn‒soybean-based diet containing FM 4%, 2) BSF25: corn‒soybean-based diet containing FM 3% and BSF larvae 1%, 3) BSF50: corn‒soybean-based diet containing FM 2% and BSF larvae 2%, 4) BSF100: corn‒soybean-based diet containing BSF larvae 4%.

Results: The study found no significant differences among the treatment groups in BW and ADG during the experimental period. However, an increased tendency of ADFI was observed (linear, p=0.09), and G:F ratio tended to decrease as the replacement rate of fish meal with BSF larvae increased (linear, p=0.06). During phase I, creatinine concentration decreased linearly as BSF larvae level increased (linear, p=0.02). During phase II, a linear response was observed in the change of glucose concentration as an increase in BSF larvae level (linear, p=0.02). Meanwhile, pigs fed with increasing BSF larvae levels showed increased albumin and total protein concentration trends (linear, p=0.05, p=0.05).

Conclusion: Defatted BSF larvae can replace up to 50% of FM in weaning pig diets without detrimental effects on performance, blood metabolites, or immune response.These reassuring findings suggest that BSF larvae could be a sustainable and effective replacement for fish meal in pig diets.