Digestibility and pricing of Chlorella sorokiniana meal for use in tilapia feeds

Abstract

Several microalgae contain in excess of 50 % crude protein with amino acid profile comparable to that of fish meal. In addition, high polyunsaturated fatty acid contents encourage their use in animal feeding and nutrition, particularly in the formulation and processing of aquafeeds. This study aims at estimating the feasibility of Chlorella meal as feed ingredient for the feeding and nutrition of farmed tilapia based upon digestibility data. Juvenile tilapia were stocked in conical-bottomed tanks (200 L) with superficial, continuous water flow, and fed to apparent satiation in three daily meals with a reference diet and a test diet containing 30 % lyophilized Chlorella sorokiniana added of an inert marker. Feces were collected overnight by sedimentation in refrigerated, plastic containers coupled to the tanks and analyzed for determination of chemical composition and inert marker contents to estimate apparent digestibility coefficients (ADCs) of protein and energy of Chlorella meal; registered ADCs of Chlorella meal were 90.5 and 84.22, respectively. A pricing model considering the quantity of digestible nutrient was proposed based on ADCs of Chlorella and compared with the price of fishmeal (FM) and soybean meal (SBM). The indicative prices to elicit the use of Chlorella as a protein source rather than FM or SBM for the feed and nutrition of tilapia were 2.65 USD kg -1 and 0.66 USD kg -1 , respectively.

Towards sustainable and ocean-friendly aquafeeds: Evaluating a fish-free feed for rainbow trout (Oncorhynchus mykiss) using three marine microalgae species

“…The digestibility of feed ingredients is key information for formulating sustainable feeds, but publicly available information on digestibility for specific microalgal species in aquafeeds is virtually non-existent (Barone et al, 2018). This lack of information often leads researchers and practitioners to extrapolate the nutritive value of microalgae from their chemical composition.…”

Identification of microalgae cultured in Bold’s Basal medium from freshwater samples, from a high-rise city

“…Chlorella vulgaris is widely used in nutrition and biodiesel 30 . Additional to these commercial uses, Chlorella sorokiniana has pharmaceutical and fish feed uses 31 – 33 . Chlorella ellipsoidea is additionally known to have pharmaceutical potential 34 .…”

Exposure of Nile Tilapia (Oreochromis niloticus) Fingerlings to a Saxitoxin‐Producing Strain of Raphidiopsis (Cylindrospermopsis) raciborskii (Cyanobacterium) Reduces Growth Performance and Increases Mortality Rate

“…The ingestion of cyanobacteria by tilapia is well documented. Because it is a filtering species (Torres et al 2016), tilapia has a high capacity to use different species of microalgae as a source of nutrients, with protein digestibility of up to 90% (Barone et al 2018). Thus, this "extra contribution" not counted as protein from R. raciborskii explains the higher protein retention by the fingerlings in the CYANO treatment.…”