Amaranth leaf offers potential protein for fishmeal replacement

© iStock/sezer66

Tilapia growth and production supported on a 80% fishmeal replacement diet, say researchers.

An international research team involving scientists based in universities in the US and Kenya examined the use of vegetable-based proteins as fishmeal (FM) replacement in Nile tilapia diets.

The group published their work in the journal of Aquaculture Reports.

“The objective of this study was to investigate the nutritional quality of [amaranth leaf protein concentrates] ALPC and the effects of replacing FM with ALPC in a formulated feed on the growth performance, nutrient utilization, carcass proximate composition and digestibility of Nile tilapia (Oreochromis niloticus),” they said.

In the trials, researchers found that production was sustained with fishmeal replacement levels reaching 80%, but that all fishmeal could not be replaced, they said. However, more work may be needed to improve processing of the plant for feed use.

“It may be concluded that ALPC can replace up to 80% FM in the diet of O. niloticus without compromising growth, nutrient utilization, whole body composition and nutrient digestibility,” said the researchers. “The reduced growth performance of fish fed diets with up to 0% FM may be related to the limiting level of methionine and leucine, high anti-nutritional factors which depressed the feed intake and growth in fish at high levels of plant protein.”

Why amaranth leaf?

As farmed finfish production continues to expand, more high quality aqua feed is needed to sustain the industry, said the researchers. However, it also is putting increasing strain on limited amounts of fishmeal available.

Alternative protein ingredients are needed to support continued expansion of the aquaculture industry, they said. Several plants have been considered as partial or complete FM replacements because they offer a similar amount of protein and a good amino acid profile.

But when used as complete or partial replacements for fishmeal results have been variable, they said. “Therefore research into utilization of plant protein ingredients to replace FM will more likely continue,” they added.

Some plants in the genus amaranthus have been of interest because of the nutritional content, said the researchers. The plant also is quick growing and inexpensive to produce.

“Previous research has demonstrated that amaranth grain has hypocholesterolemic effects,” said the researchers. “For instance it was reported that diets containing 20% Amaranthus cruentus grains and 5% crude amaranth oil have a decreasing effect on total cholesterol and low- or very low density lipoprotein (LDL) in hamsters and hypercholesterolemic rabbits.”

Bu, little work has been done evaluating the plant for use in aqua feeds, they said. 

Methods and material

In the study, Nile tilapia fingerlings were given diets with varying levels of fishmeal and an alternative protein generated from amaranth leaves, said the researchers. The feeding test ran for 160 days.

In the trial diets 100%, 75%, 50%, 40%, 20% or 0% of the fishmeal protein was replaced with the amaranth leaf protein concentrates (ALPC), they said. Diets were comprised of locally-sourced ingredients including wheat bran, brewery waste, perch oil, cassava and mineral and vitamin premix.

Ingredients, diets and fish were checked for moisture content, total ash, ether extract and crude fiber amounts, they said. Amino acid levels were also checked.

Fish were evaluated for performance, nutrient use, whole body composition, survival and for apparent nutrient digestibility, they said. The feed conversion ratio (FCR) and specific growth rate (SGR) also were calculated. 


“We demonstrate that it is possible to replace up to 80% of fish meal with ALPC without compromising the performance O. niloticus,” said the researchers. “These results demonstrate that although it is possible to replace [a] large part of fish meal with ALPC, it is not possible to eliminate it in Nile tilapia diet as alternative protein ingredient.”

After 160 days, the research team found that fish getting diets that included more than 80% ALPC had reduced growth, nutrient utilization and a poorer FCR than those getting more diets with more fishmeal, they said.

“Treatments with 100% substitution levels of FM with ALPC resulted in lower final weight, weight gain and FCR,” they said. “Highest fish survival was observed in tanks with 100% FM, while diets where substitution of FM was done showed comparable survival (74–77%) regardless of the substitution levels of FM by ALPC.”

Fish getting diets with lower amounts of fish meal had higher daily feed intake, they said. Carcass moisture and protein were not altered by the different diets, but lipid content was slightly lowered with more ALPC in the diet and body ash was increased.

Apparent nutrient digestibility for protein was best for fish getting diets with 100% to 40% fishmeal, said the researchers. However, lipid digestibility was similar for fish on all diets save those getting no fishmeal and carbohydrate and dry matter digestibility was comparable for all diets.

There were some challenges to the use of ALPC in the diet as it had a “considerable presence” of anti-nutritional factor, they said. And, except for potassium, fishmeal had a higher amount of multiple essential amino acids.

Source: Aquaculture Reports

Title: Characterization of the nutritional quality of amaranth leaf protein concentrates and suitability of fish meal replacement in Nile tilapia feeds

DOI:  published online before print: 10.1016/j.aqrep.2017.01.003

Authors: C Ngugi, E Oyoo-Okoth, J Manyala, K Fitzsimmons, A Kimotho 

Related News

'There isn’t really a sense of urgency about the alternative protein topic right now in the feed space. It is not a burning platform. But we want to get the conversation started.' © istock/ipopba

Project aims to find protein feeds ‘fit for the future’

© Leroy Group

Stable fishmeal prices forecast, alternative protein players could face choppy waters

© istock/chenguzheng

CPF looks to reduce fishmeal levels in shrimp feed

What is the low-down on the fishmeal market?

Fishmeal has shifted from being a bulk commodity traded on price to a strategic ingredient: Rabobank

Danes producing fishmeal substitute

Danes producing fishmeal substitute

© Ltd

Fluctuation in fishmeal prices trigger for innovation: Nutreco


Fishmeal prices forecast lower in 2016

Canada: local fishmeal market could benefit from short-term exemption

Canada: local fishmeal market could benefit from short-term exemption

© istock

Irish fishmeal plant redeveloped to the tune of €30m


Drop in prices but uncertainties remain in fishmeal market

© istock

Fishmeal prices predicted to soften in 2017 (compared to 2016)

Skretting looks to insects and algae as fishmeal alternatives

Skretting looks to insects and algae as fishmeal alternatives

Slavery in fishmeal supply: IFFO looks for ways to widen global standard to ensure worker safety

Slavery in fishmeal supply: IFFO looks for ways to widen global standard to ensure worker safety

© iStock/JudyDillon

US: Prairie Aquatech to generate novel soy-based fishmeal replacer

Fishmeal free? Protein alternatives key to Australia’s prawn future

Fishmeal free? Protein alternatives key to Australia’s prawn future


Fishmeal-free diets alter gut microbes, but cleared for use in recirculating systems

"the Board felt that the time had come to widen the ambition of the standard to address the whole global marine ingredients industry..."

Responsible supply: IFFO changes fish oil and fishmeal sourcing rules

Related Products

See more related products

Submit a comment

Your comment has been saved

Post a comment

Please note that any information that you supply is protected by our Privacy and Cookie Policy. Access to all documents and request for further information are available to all users at no costs, In order to provide you with this free service, William Reed Business Media SAS does share your information with companies that have content on this site. When you access a document or request further information from this site, your information maybe shared with the owners of that document or information.