COMPARATIVE ASSESSMENT OF SPENT GRAIN AND COW DUNG AS SUBSTRATES FOR GROWTH AND NUTRIENT CONVERSION IN HERMETIA ILLUCENS LARVAE

Abstract

The growth and nutrient accumulation performance of Hermetia illucens larvae fed on a variety of common organic substrates, such as spent grain (SG) and cow dung (CD), were evaluated in the current study. In order to evaluate the performance of larvae fed on the two substrates for 12 days, a number of laboratory experiments were conducted, including measurements of body weight, survival rate, proximate composition, and Nutrient Enrichment Factor (NEF). At the end of 12 days, larvae given SG had a total sampled larval weight (30 individuals) of 1907.07 ± 242.45 g, a substantially higher body weight than those fed CD (425.61 ± 11.12 g, P = 0.012), despite equal survival rates. Furthermore, larvae fed SG had a considerably greater protein content (41.62%) and fat content (16.61%) than larvae given CD (25.32% protein and 6.83% fat, respectively). In a similar vein, larvae fed SG had a far higher energy content (2898.64 kcal/kg) than larvae given CD (1495.53 kcal/kg). Comparative analysis suggested that higher substrate protein, fat, and energy contents were associated with increased larval weight, while higher ash content appeared to limit growth. The results of this study provide a comparative evaluation of spent grain and cow dung as locally available substrates, highlighting differences in growth performance and nutrient conversion efficiency under controlled conditions.