Effects of dietary corn and protein levels on physical properties of extruded feed pellets and growth performance of rainbow trout, Oncorhynchus mykiss

• Published in: Journal of the World Aquaculture Society 2024-02, Vol.55 (1), p.125-148
• Main Authors: Alkoei, Amir Soltani, Jalali, Sayed Mohammad Ali, Jalali, Seyed Amir Hossein, Kheiri, Farshid
• Format: Article
• Language: English
• Subjects: Alanine; Alanine transaminase; aquaculture; Aspartate aminotransferase; aspartate transaminase; blood serum; Body weight; Body weight gain; Bulk density; Conversion ratio; Corn; Degradability; Design of experiments; dietary protein; Experimental design; Extrusion; Feed conversion; feed conversion ratio; feed processing; Feeds; Fish; Flour; Food conversion; Freshwater fishes; gelatinization; Grain; growth performance; Growth rate; hardness; hepatosomatic index; High protein diet; Leakage; Lipids; liver; Low protein diet; Mechanical properties; Modulus of elasticity; oils; Oncorhynchus mykiss; Pellets; Physical characteristics; Physical properties; protein efficiency ratio; Protein sources; Proteins; Salmon; Serum; specific growth rate; Starch; Transaminases; Trout; Vegetables; Water stability; weight gain; Wheat; wheat flour
• ISSN: 0893-8849; 1749-7345
• DOI: 10.1111/jwas.13034

The dietary protein levels and source of starch are factors in the economical production of feeds, which may change the physical quality of extruded pellets and the growth performance of fish. Eight feeds contained two protein levels and four levels of wheat flour substitutions by corn, as a 2 × 4 factorial experimental design, were produced by a twin‐screw extruder machine and fed to 800 rainbow trout. The results showed corn grain reduced expansion ratio, water stability at 120 and 260 min, starch gelatinization (SG), and apparent degradability, while bulk density (BD) and oil leakage of feed pellets increased. The high protein diets displayed the most BD, lower oil leakage, SG, and elastic modulus. The high protein feeds improved the final body weight, weight gain, specific growth rate, and feed conversion ratio (FCR) of fish. The corn grain reduced the FCR and promoted the trout's protein efficiency ratio. Lipid proportions of fish livers corresponded to hepatosomatic index and serum concentrations of aspartate aminotransferase and alanine aminotransferase. In general, corn, as the starch source in the high and low‐protein extruded feeds, can be replaced at levels of 33%–66% of wheat flour without adverse effects on the physical characteristics of feed pellets and the growth performance of rainbow trout.