The use of lignin as a marker in a digestibility trial on Tenebrio molitor insect larvae

The Tenebrio molitor or yellow mealworm is a widely studied alternative source of protein in animal nutrition. This study aimed to explore the use of lignin as a marker in the digestibility research of Tenebrio molitor. The digestibility results obtained from the total collection method were compared with those determined using a marker, and the data was statistically processed. It used two types of feed: wheat bran and oat flakes. The concentration of lignin varied greatly between the two, with wheat bran containing 2.17% and oat flakes 0.51%. The results show that the digestibility determined by both the direct method and the method using lignin as a marker is very similar for wheat bran; however, there is a notable difference for oat flakes feed. High values of determination coefficients (R2) show a high correlation between digestibility values obtained by the two methods. Yet, regression analysis shows that only in the case of wheat bran two methods are resulting in similar values. In the case of oat flakes, systematic regression bias is obvious, as confirmed by intercept and slope significant p values. Lignin can serve as a useful marker in digestibility trials involving insects. The concentration of lignin in the feed appears to be crucial for obtaining accurate results. However, this is only a preliminary trial, and further research is needed to draw definitive conclusions.