Dietary full-fat or defatted black soldier fly larvae can replace protein sources with no detrimental effect on growth performance or intestinal health of nursery pigs

Abstract This work aimed to determine the effects of dietary full-fat or defatted black soldier fly larvae (BSFL) to replace protein sources on growth performance, blood parameters, intestinal morphology, and intestinal microbiota in nursery pigs and to investigate the effects of dietary defatted BSFL at up to 30% at the expense of protein sources on growth performance in nursery pigs. In Exp. 1, a total of 36 barrows with an initial body weight of 7.0 kg (SD = 0.8) were allotted to three dietary treatments in a randomized complete block design with four replicate pens per treatment and three barrows per pen. A corn-soybean meal (SBM)-whey-based control diet was prepared with soy protein concentrate and fish meal as additional protein supplements. Two additional diets were prepared to include 20% full-fat BSFL or 20% defatted BSFL to replace soy protein concentrate and fish meal to maintain the same energy and nutrient concentrations in all diets. In the 28-d feeding trial, pigs fed the diet containing defatted BSFL tended to consume more feeds (P < 0.10) than other groups during days 14 to 28 and the overall period. On day 28, the serum blood urea nitrogen in pigs fed the control diet was less (P < 0.05) than that fed the full-fat or defatted BSFL, but fecal score and jejunal morphology did not differ among the treatment groups. Relative abundance of Mycoplasma in the ileal digesta was less (P < 0.05) in the pigs fed the diet containing full-fat or defatted BSFL compared with the control group. In Exp. 2, a total of 192 pigs with an initial body weight of 7.8 (SD = 1.2 kg) were randomly allotted to one of four dietary treatments in a randomized complete block design with six replicate pens per treatment and four barrows and four gilts per pen. A control diet was mainly based on corn, SBM, fermented SBM, fish meal, and spray-dried plasma protein (SDPP). Three additional diets were prepared to contain 10%, 20%, and 30% defatted BSFL to replace SBM, fermented SBM, fish meal, and SDPP to maintain for the same energy and nutrient concentrations. Average daily gain, average daily feed intake, gain:feed, and fecal score were not affected by increasing dietary defatted BSFL. Overall, dietary BSFL did not compromise growth performance or intestinal health in nursery pigs. BSFL can be used in nursery pig diets to replace other protein sources without negative effects.