Sacha inchi meal as a fish-meal replacer in red hybrid tilapia (Oreochromis niloticus × O. mossambicus) feeds: effects on dietary digestibility, growth metrics, hematology, and liver and intestinal histology

Abstract

The utilization of sustainable and innovative raw materials to substitute for traditional fishmeal (FM) ingredients is required for the aquaculture sector. Sacha inchi meal (SIM), a by-product of sacha inchi oil, is one of the promising FM replacers. In the present study, four isonitrogenous and isolipidic (approximately 30 and 8%, respectively) diets containing 0, 270, 330, and 415 g/kg of SIM (SIM0, 60, 80, and 100, respectively) were prepared. Four replicate groups of red hybrid tilapia (15.87 ± 0.02 g/fish, 20 fish per replicate, 80 fish per diet) were randomly distributed into 16 glass tanks (100 L each) and manually fed one of the test diets until apparent satiation twice daily for 10 weeks. All fish were used to calculate growth parameters. Dietary SIM replacement increased growth performance and feed conversion ratio (P < 0.001 for most parameters). The SIM80 diet resulted in the highest final weight (56.43 g/fish), weight gain (40.53 g/fish), specific growth rate (1.81%/day), and protein productive value (37.30%). The apparent digestibility coefficient of protein was significantly increased (81.65 ‒ 87.65%) by replacement of FM with SIM (P < 0.001) with a significant negative effect observed in the fish fed SIM100 (78.30%). Hematology, total cholesterol, triglycerides, and low-density lipoprotein cholesterol were significantly decreased in all SIM-supplemented groups (P < 0.05). Aspartate aminotransferase and alanine transaminase levels were significantly increased with the highest levels in the SIM100 group (75.20 and 42.61 UL−1, respectively, P < 0.001). Among the histological differences observed in the liver, nuclei shifting and hepatocyte vacuolization were the main abnormalities in the fish fed the SIM80 and SIM100 diets. Intestinal villi height and thickness were increased by the dietary replacement (P < 0.05). These results demonstrate that SIM can replace FM by up to 330 g/kg (SIM80) improving growth, digestibility, blood parameters, and histological integrity.