Housefly maggot meal complement soybean meal in a fish-free diet for hybrid catfish (Clarias gariepinus ♀ x Heterobranchus longifilis ♂): Effect on growth, body composition, blood and antioxidant

A 45-day experiment was designed to study the complementary effect of maggot (Musca domestica) meal (MG) in a fishmeal-free soybean meal (SBM)-based diet on the production performance of African catfish hybrids. Four isoproteic (398.78 g/kg +/- 3.23) and iso-energetic (20.23 kJ/g +/- 0.15) diets were formulated as positive control (FM-based diet), soybean-based diets (FM-free) and soybean-based diets supplemented with 14 % MG and 21 % MG as complementary ingredients, denoted as FM, SBM, MG14 and MG21, respectively. A total of 180 healthy hybrid catfish (average initial body weight: 4.31 +/- 0.04 g) were distinctly stocked into 12 trial tanks (60L capacity) and fed to apparent satiation twice daily with their respective diets. At the end of the feeding trial, fish fed MG21 outperformed those fed other diets in final body weight (FBW), weight gain (WG), specific growth rate (SGR), and daily growth index (DGI) (p < 0.05). However, MG had no influence on feed intake (FI), feed conversion ratio (FCR), or nutrient utilization indices among the groups (p > 0.05). The MG21 supplementation improved the immunophysiological indices such as white blood cell, lymphocyte count, total protein, and globulin values compared to other groups, while haemoglobin, haematocrit, and red blood cell counts were not affected. Supplementation with MG at 21 % enhanced the antioxidant capacity of hybrid catfish with no detrimental effect on the serum alanine aminotransferase and alkaline phosphatase enzymes activities. However, the aspartate aminotransferase was found higher in MG14 and MG21 fed fish compared to other dietary groups. Based on the results obtained in this study, it can be concluded that maggot meal could be used as a complementary ingredient in place of fishmeal in soybean meal diets for the culture of hybrid African catfish. Data Availability: The data in this article is available upon request from the corresponding author.

Automated summary

A 45-day experiment was conducted to investigate the complementary effect of maggot meal in a fishmeal-free soybean meal-based diet on the production performance of hybrid African catfish. The results showed that supplementation with 14% and 21% maggot meal improved the final body weight, weight gain, specific growth rate, and daily growth index. In addition, the 21% maggot meal supplementation enhanced the immune physiological indices and antioxidant capacity without detrimental effects on certain blood parameters. These findings support the use of maggot meal as a complementary ingredient in soybean meal diets for the culture of hybrid African catfish.