Aquaculture America 2020

February 9 - 12, 2020

Honolulu, Hawaii

ALGAL MEALS FROM Arthrospira platensis AND Schizochytrium limacinum AS COMPLETE REPLACEMENT OF FISH MEAL, FISH OIL AND SOY PROTEIN CONCENTRATE IN FEEDS FOR TILAPIA

Armando García-Ortega*, Alyssa MacDonald, Rajesh Jha
 
 College of Agriculture, Forestry and Natural Resource Management
University of Hawaii at Hilo
 200 W. Kawili St.
Hilo, HI 96720, USA
agarciao@hawaii.edu
 

A lgal meals  from Arthrospira platensis (Spirulina) and Schizochytrium limacinum  were used  to completely replace fish meal (FM) ,  fish oil (FO)  and soy protein concentrate (SPC)  in feeds for  juvenile hybrid tilapia (Orechromis niloticus x  O. mossambicus).  Five isonitrogenous and isoenergetic feeds were formulated to replace fish and soy ingredients at 0%, 25%, 50%, 75% and 100% by algal meals (ALG) . Feeds were supplemented with lysine and methionine at increasing levels  of ALG inclusion  to meet the essential amino acids requirements of fish. Taurine was also supplemented in all feeds. A feeding trial was performed in fish with an initial weight of 0.9 ± 0.1 g. Each feed treatment was tested in triplicate 90 L tanks in a water recirculation system at a density of fish 15 per tank. Feeds were manually fed to fish twice per day at 8 am and 2 pm for nine weeks.  Water quality parameters during the trial were: temperature: 28.3 ± 0.2°C, salinity 0.1 ± 0.0 ppt, dissolved oxygen 6.5 ± 0.1 mg/L, pH 6.7 ± 0.3 and total ammonia nitrogen 0.0 ± 0.0 mg/L. At the end of trial  data on fish weight gain, feed utilization and nutrient retention among treatments were evaluated with ANOVA and regression analyses.

Fish f eed intake was significantly higher (P<0.05) with increasing algal meals content in feeds, the highest  found  in treatments ALG 50, ALG 75 and ALG 100. The FM, FO, SPC-based feed (ALG 0) produced significantly  lower growth (P<0.05) than all  the  feeds  containing ALG, including ALG 100. Fish g rowth w as  the highest  in feeding treatments  ALG 75 and ALG 50.  A quadratic regression analysis to  study t he relationship between fish weight gain and increasing replacement of FM, FO and SPC by algal meals indicated  that maximum fish weight gain can be achieved at 70% replacement level.  No significant differences (P>0.05) were found in FCR or feed efficiency among diets. However, nitrogen retention  in fish  was significantly higher (P<0.05) with ALG 50 and ALG 75, followed by ALG 100. No significant differences were found in final body proximate composition, with the exception of ash content. It's concluded that a feed made with 100% A. platensis  and  S. limacinum  as  the sole sources of protein and lipid  produce  higher  growth and feed utilization in  hybrid tilapia juveniles  than conventional  fish  feed ingredients ,  confirming  the  quality and  suitability of  these algal in feeds for omnivorous farmed fish.