Effects of dietary zeolite (clinoptilolite) levels on growth performance, feed utilization and waste excretions by gilthead sea bream juveniles (Sparus aurata)
The study investigates the impact of dietary zeolite (clinoptilolite) on the growth performance, feed utilization, waste excretion, and nutrient absorption in juvenile gilthead sea bream (Sparus aurata). Conducted over ten weeks, the experiment involved five dietary treatments with varying zeolite levels (0, 10, 20, 30, and 40 g/kg) in a commercial diet. Key findings include significant improvements in final weight, specific growth rate (SGR), and feed conversion efficiency (FCE) with increasing zeolite levels, particularly peaking at 30 g/kg. The protein efficiency rate (PER) also showed linear and quadratic increases with zeolite supplementation.
While body moisture and lipid content remained unchanged, there were trends indicating increased ash and protein levels. Notably, liver iron (Fe) levels increased with zeolite, while aluminum (Al) levels in fillet showed a quadratic response. The apparent digestibility coefficients (ADCs) for dry matter, protein, and lipid did not differ significantly, although energy ADCs exhibited a quadratic trend. Waste excretion analysis revealed a tendency for reduced total nitrogen waste (TNW) and dissolved nitrogen waste (DNW) with higher zeolite levels.
Intestinal morphology assessments indicated no significant changes in anterior intestinal folds or gut length, but posterior intestinal folds decreased with increased zeolite. The study concludes that the optimal dietary inclusion of zeolite for enhancing growth and feed efficiency in juvenile gilthead sea bream is approximately 27.1 g/kg, without adverse effects on fish or human health regarding heavy metal accumulation.
This research paper is significant in the field of aquaculture nutrition, particularly for marine species, as it addresses a gap in research regarding the use of natural zeolites in fish diets. The findings contribute to ongoing discussions about optimizing feed formulations to enhance growth performance and reduce waste in aquaculture systems. By demonstrating the benefits of zeolite supplementation, the study offers practical insights for aquaculture practitioners aiming to improve feed efficiency and fish health while minimizing environmental impacts through reduced waste excretion. The research also highlights the importance of understanding nutrient digestibility and heavy metal accumulation, which are critical for ensuring the safety and quality of fish products for human consumption.
