Modelling digestive hydrolysis of nutrients in fish using factorial designs and desirability function

Area of Science:

• Animal Nutrition
• Biochemistry
• Aquaculture

Background:

• In vitro models simulate digestive hydrolysis to understand nutrient bioavailability.
• Optimization algorithms can predict favorable conditions for nutrient digestion.

Purpose of the Study:

• Determine optimal conditions (pH, enzyme:substrate ratio, time) for protein and carbohydrate hydrolysis in gilthead seabream.
• Apply a desirability function for multi-objective optimization of nutrient digestion.

Main Methods:

• Response Surface Methodology (RSM) models were used for in vitro assays.
• A two-phase digestion process (stomach and intestine) was simulated using species-specific enzymes.
• Experimental design considered gilthead seabream physiology and culture conditions.

Main Results:

• The intestinal phase significantly contributed to protein hydrolysis, influenced by pH, enzyme ratio, and time.
• Carbohydrate hydrolysis depended on substrate amount and pH, with time having no significant effect.
• Physiological conditions favored protein over carbohydrate hydrolysis, mirroring in vivo observations.

Conclusions:

• Mathematical models and optimization provide practical insights for gilthead seabream feed formulation.
• Optimized digestion conditions can enhance nutrient bioavailability in aquaculture feeds.
• Understanding species-specific digestive processes is crucial for sustainable aquaculture.