Pellet physical quality affects digestion in spotted seabass

Summary

This study investigated how pellet physical quality (PPQ) affects the digestive physiology and growth performance of spotted seabass, Lateolabrax maculatus. The contrasting PPQ was achieved by varying the main dietary ingredients (protein or carbohydrate sources) and adjusting extrusion processing conditions (preconditioning moisture and die temperature).
The results showed that both dietary ingredients and processing parameters influenced nutrient digestibility. Extrusion conditions affected not only PPQ but also nutrient bioavailability. PPQ affected fish digestive physiology and performance, with pellet hydration time, bulk density, and expansion ratio exhibiting the most frequent and significant effects. Among these, hydration time emerged as an indicator of how feed moisturizes and disintegrates in the fish stomach—processes that, in turn, influence nutrient digestion.