The nutritive value of red seaweed, Kappaphycus alvarezii meal in formulated feed of juvenile Asian seabass, Lates calcarifer

• Main Author: Nik Siti Zaimah Safiin
• Format: Thesis
• Language: English; English
• Published: 2014
• Subjects: QK504-(638) Cryptogams
• Online Access: https://eprints.ums.edu.my/id/eprint/38909/1/ABSTRACT.pdf; https://eprints.ums.edu.my/id/eprint/38909/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/38909/
• Institution: Universiti Malaysia Sabah

Two separate trials were conducted to evaluate the potential of seaweed meal (Kappaphycus alvarezii) as an ingredient in the formulated diets of Asian seabass, Lates calcarifer. Experiment 1 aimed to evaluate the possibility of replacing commercial feed binder, carboxymethyl cellulose (CMC) with different inclusion levels of K. alvarezii meal at 2, 4, 6, 8 or 10% (SW2, SW4, SW6, SW8 or SW10). A diet without seaweed inclusion (SW0) served as the control treatment. Triplicate groups of 15 fish were randomly stocked in cylindrical cages placed in a 10-tonne high density polyethylene (HDPE) tank and fed experimental diets for eight weeks. Water stability indices (after 60 min) of SW6, SW8 and SW10 were not significantly different (P>0.05) from the control diet (SW0). The highest weight gain and specific growth rate (SGR) were observed in fish fed SW6 (382.85±58.38% (P<0.05) and 2.81±0.21%/d, respectively) and the poorest was in SW0 (301.95±46.31% and 2.48±0.20%/d, respectively). No significant difference on feed conversion ratio (FCR) (1.54±0.20-1.83±0.05) was detected in all dietary treatments. Survival rate was above 96% and not affected by the inclusion level of seaweed meal. Insignificant (P>0.05) level of whole-body moisture, protein, lipid and ash were shown in all treatments. In Experiment 2, a 10-week feeding trial was carried out to determine if cooking process can improve the utilization of seaweed meal. Experimental diets were formulated with cooked seaweed meal at 6, 10, 14, 18 and 22% inclusion levels (SW6, SW10, SW14, SW18 and SW22, respectively). Diets with raw seaweed at 6% (SW6R) and without seaweed (SW0) inclusion served as the control treatments. Triplicate groups of 20 fish were stocked in a 150 L fibreglass tank and fed until satiation twice daily. Faeces were collected from week 6 until week 10 for the measurement of diet’s apparent digestibility coefficient (ADC). Cooked seaweed, SW6 (97.48±0.37), SW10 (97.99±0.32), SW14 (98.35±0.29), SW18 (98.36±0.16) and SW22 (98.31±0.12) performed significantly (P<0.05) better in terms of water stability than the uncooked seaweed, SW6R (95.25±0.50) and comparable (P<0.05) with control diet, SW0 (98.26±0.25). In this experiment, fish fed 6% cooked K. alvarezii meal (SW6) showed significantly (P<0.05) higher weight gain and SGR (785.02±30.70% and 3.11±0.05%/d, respectively) and resulted the best FCR (1.18±0.06) compared to other treatment. Survival was affected by the inclusion of seaweed meal in the diets, where the highest inclusion level (SW22) resulted in the poorest survival (83.00±5.77). Dry matter ADC ranged from 59.03±7.88% to 73.65±1.19%. Protein ADC of the diets decreased with increasing seaweed level and ranged from 69.06±0.49% to 92.05±0.09%. Lipid ADC were not significantly difference (P>0.05) among treatments. In conclusion, the best incorporation of seaweed meal as binder was at 6% replacement level either raw or cooked seaweed which consistently giving the best growth performance, feed efficiency, survival, diet’s digestibility and cost effective. However, replacement level from 6% to 10% can be considered to be include as it improve diet’s stability and suitability used as feed binder to replace CMC and eventually improve the fish performance.