Inclusion of 10% seaweed meal in diets for juvenile and on-growing life stages of Senegalese sole (Solea senegalensis)

• Published in: Journal of applied phycology 2018-12, Vol.30 (6), p.3589-3601
• Main Authors: Moutinho, S., Linares, F., Rodríguez, J. L., Sousa, Vera, Valente, L. M. P.
• Format: Article
• Language: English
• Subjects: Algae; Biomedical and Life Sciences; Body composition; Body weight; Diet; Ecology; Feeding; Fillets; Fish; Fish fillets; Freshwater & Marine Ecology; Intestine; Iodine; Life assessment; Life Sciences; Mineral nutrients; Nutrient retention; Nutrient utilization; Nutritive value; Physical growth; Plant Physiology; Plant Sciences; Proteins; Seafoods; Seaweed meal; Seaweeds; Selenium; Sole; Solea senegalensis; Undaria pinnatifida; Weight
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-018-1482-6

The long-term inclusion of 10% seaweed meal ( Ulva rigida and Undaria pinnatifida ) was evaluated in diets for Senegalese sole ( Solea senegalensis ). Triplicate groups of fish with an initial body weight of 23 g were fed the experimental diets (ULVA and UNDARIA) and compared to fish fed a control diet with no seaweed included (CTRL), both in juvenile (after 5 months of feeding, up to 60 g) and on-growing stages (after 9 months of feeding, up to 160 g). In the early juvenile phase, the inclusion of seaweeds did not affect fish growth, but final body weight was significantly lower in on-growing fish fed the UNDARIA diet. Overall, growth performance was also reduced in fish fed the UNDARIA diet, with a significantly lower daily growth index. Whole-body composition and nutrient retention (% intake) remained unaffected by the dietary treatment, but by the end of the growth trial fish fed the UNDARIA diet had a significantly lower protein gain associated with significantly lower intestinal villi width. At the end of the experiment, fish fed the UNDARIA diet had a significantly higher iodine flesh content (375.7 μg kg −1 ) than those fed the CTRL (187.5 μg kg −1 ) or ULVA (199.3 μg kg −1 ) diets, whereas selenium content was similar in all groups of fish. In conclusion, U. rigida seems a valid ingredient for Senegalese sole diets without affecting fish growth or nutrient utilization. U ndaria pinnatifida was an effective way of naturally fortifying the nutritional value of sole fillets for human consumption, but resulted in growth impairment, so a lower inclusion level should be further evaluated.