Abstract
Protein production from poultry, particularly broiler chickens, is considered a key component of future global food security, due to its relatively high sustainability. However, the use of resources such as soybean oil remains a concern. Black soldier fly (Hermetia illucens [HI]) larvae oil represents a promising alternative due to a relatively rapid rearing cycle and ability to utilize organic waste as growth substrates. This study investigated how replacing a commercial lipid source such as soybean oil, with HI larvae oil affects broiler growth performance, meat quality traits, fatty acid (FA) profile, and caeca microbiome. A total of 552 one-d-old male Ross 308 broilers, with equal initial weights (48.89 ± 0.18 g; P = 0.597), were allocated to three dietary treatments with 8 replicate pens per group (23 birds/pen). All birds received the same commercial basal diet, formulated to be isoenergetic and with the same amino acid profile, differing only in the source of the supplemented oil: 100% soybean oil group (CON), 50% soybean oil + 50% HI larvae oil group (MIX), or 100% HI larvae oil group (HIO). Growth performance parameters were recorded at the end of each feeding phase (14, 28, and 42 d). At slaughter (42 d), 10 breasts (pectoralis-major muscle) and thighs (extensor-iliotibialis muscle) samples per group were collected for meat quality assessment, and caecal content samples were obtained from 8 birds/group for microbiome analysis. Growth performance metrics showed an improvement in feed conversion ratio during the starter phase for HI larvae oil-fed groups (1.54 vs. 1.45 vs. 1.46 for CON, MIX, and HIO, respectively; P < 0.001) and comparable performance across the trial. Meat quality traits remained within commercially acceptable ranges, with minimal effects observed, apart from variations in breast fillet redness and thigh protein oxidation. FA analysis indicated higher levels of saturated FAs in the HI groups, with a concurrent reduction in omega (n)-6 levels and a more balanced n-6 to n-3 ratio (16.47 vs. 15.18 vs. 11.60 for CON, MIX, and HIO, respectively; P < 0.001). The caecal microbiome revealed stable diversity across groups, with only minor shifts in relative abundance. Overall, the findings showed that HI larvae oil is an effective alternative to conventional vegetable lipid sources in poultry nutrition, with added potential to enhance growth performance during the early growth stages.