The effect of partial replacement of soybean oil with insect fats on dietary short-term preference in laying hens

Assessment of the acceptance of novel feed ingredients provides valuable insights into their potential integration into practical animal feed formulations. However, despite growing interest in insect-derived feed ingredients, information on the short-term palatability of insect fats in laying hens remains scarce. This study evaluated the effect of partially replacing soybean oil (SO) with fats derived from Hermetia illucens larvae (HI) and Tenebrio molitor larvae (TM) on short-term feed preference of laying hens. Forty-eight 34-week-old hens were individually housed in enriched cages. After a seven-day training period, birds underwent double-choice tests with three mash diets containing 5.7% added fat: control (C) with 5.7% SO; HI with 3.7% SO and 2% HI fat; and TM with 3.7% SO and 2% TM fat. Two equally sized feeders were placed side by side in front of each cage. Each hen completed three tests (C vs. C, C vs. HI, and C vs. TM) over three days, in a balanced randomised order. Following a 2–h fasting period, each test comprised two 120–min feeding sessions separated by a 2–h fasting interval. Feeder positions were reversed between sessions to minimise positional bias. Feed intake was analysed using a linear mixed model fitted by restricted maximum likelihood. None of the direct within-comparison contrasts reached statistical significance (p > 0.05). At 2% inclusion neither HI nor TM fat produced detectable differences in short-term feed preference. These novel findings indicate that both insect fats can be incorporated without impairing feed palatability, supporting their potential use as alternative lipid sources.