Medium-chain fatty acid-rich oils with varying free fatty acid levels as alternatives to soybean oil in broiler starter diets

This study evaluated the effects of a 4% dietary supplementation with oils rich in medium-chain fatty acids ( MCFA ), varying in free fatty acids ( FFA ) content, on fatty acid ( FA ) digestibility and intestinal health in starter broilers. A total of 512 one-day-old female broilers (Ross 308) were fed four experimental diets (8 replicates/treatment), replacing soybean oil ( SO ) with black soldier fly larvae oil ( BSFO ), palm kernel oil ( PKO ), or palm kernel FA distillate from physical refining ( PKFAD ). Broilers fed SO, BSFO, or PKO showed higher body weight, daily gain, feed intake, and apparent metabolizable energy ( AME ) intake on day 21 than those fed PKFAD ( P < 0.001). Diets with BSFO and PKO oils, rich in MCFA (36-49%) and low in FFA (< 3%), maintained ileal total FA digestibility comparable to the SO diet ( P < 0.001), achieving up to 89% of C12:0 absorption at the distal ileum, of which over 92% occurred in the jejunum. In contrast, PKFAD showed the lowest digestibility coefficients for most FA, likely due to the high long-chain saturated FA ( LCSFA ; 38.2%) and FFA (68.2%) contents of the added oil. Intestinal morphology and ileal microbial counts were unaffected, but cecal propionate concentrations were higher in BSFO and PKO compared to PKFAD, indicating enhanced microbial fermentation. These results support including BSFO and PKO at 4% in broiler starter diets as alternative energy sources, promoting rapid and efficient MCFA absorption whereas maintaining growth and gut health. In contrast, high FFA levels in PKFAD limited MCFA absorption and negatively affected AME intake and performance.