Growth, Hematobiochemical Changes, and Gut Bactericidal Potential of Atama, <i>Heinsia crinita,</i> Leaf Extract–Based Diet on Nile Tilapia

Feed additives are essential for economic sustainability in aquaculture. However, the use of synthetic chemical additives in fish culture can lead to antibiotic resistance, reduced drug potency, and decreased profitability. Hence, the need for an eco-friendly alternative such as Atama, <i>Heinsia crinita</i>, leaf. Therefore, the presence of metabolites was characterized in Atama leaves extract (ALE) using a gas chromatography-mass spectrophotometer (GC-MS), while minimum inhibitory concentration (MIC) and zone of inhibition (ZI) were determined against some selected pathogenic organisms using standard methods. Furthermore, the effects of dietary ALE on growth performance, intestinal microbiota, hematology, and liver function enzymes were examined in Nile tilapia, <i>Oreochromis niloticus</i>. Four diets of 350 g/kg crude protein were formulated and fortified with ALE at 0.0 (control), 2.0, 4.0, or 6.0 g/kg diet. Each diet was fed to Nile tilapia juveniles (4.0 ± 0.63 g) to apparent satiation three times a day for 56 days. The GC-MS analysis of ALE revealed nine metabolites, with methyl stearate being the most abundant (29.1%) and neophytadiene the least (0.4%). ALE significantly (<i>p</i> < 0.05) inhibited the all-tested organisms with MIC 2.0 mg/mL and ZI ranged from 12.6 to 30.2 mm. Also, it was observed that ALE-enriched diets linearly significantly (<i>p</i> < 0.05) promoted fish growth, feed intake, and specific growth rate than the fish fed control diet. Conversely, the feed conversion ratio was greatly reduced (<i>p</i> = 0.001) in fish fed ALE-based diet than the basal group without major effect on the survival rate. Total viable counts of bacteria were linearly and quadratically significantly (<i>p</i> < 0.05) decreased in Nile tilapia fed with ALE-enriched diets when compared to the fish fed the control diet in an inverse relationship with ALE inclusion levels. The population of <i>Vibrio</i> Sp. (24.2 × 10⁶ CFU/g), <i>Flavobacterium</i> sp. (3.7 × 10⁶ CFU/g), <i>Proteus</i> sp. (1.6 × 10⁶ CFU/g), and <i>Pseudomonas</i> sp. (52.0 × 10⁶ CFU/g) in the control group were greatly reduced in fish fed 4.0 g ALE/kg diet to 7.7 × 10⁶ CFU/g, 2.3 × 10⁶ CFU/g, 1.1 × 10⁶ CFU/g, and 1.3 × 10⁶ CFU/g, respectively. Hematological profiles and liver function indices significantly decreased at 4-6 g ALE/kg diet. In conclusion, ALE-supplemented diets inhibited the growth of selected pathogenic bacteria, promoted fish growth, improved hematological profiles, and reduced liver function enzyme activity in Nile tilapia when fed diets containing 4.0-6.0 g/kg ALE.