84
N. D. Hairuddin et al.
5.5 Microalgae as an Alternative Protein Source in Fish
Feed
Global production of aqua feeds in 2003 was estimated approximately 19.5 MT
and tilapia feeds contributes for approximately 8.1% of global aqua feed production
in the same year (Tacon et al. 2006). The most common commercial tilapia feeds
are dry sinking pellets and extruded floating pellets (Groenewald 2018). Food and
Agricultural Organization (FAO 2019) reported that under semi-intensive farming
systems, most tilapia farmers used formulated feeds while in intensive pond and tank
culture systems or in cages, tilapia farmers mostly depend on commercial pelleted
feeds. Production of high quality formulated feed needs to be maintained to ensure
high yields and large sized fish within short period of time. Although fishmeal is the
most preferred protein source in formulated feed, the availability and the increasing
price of fishmeal worldwide become more concern compared to its benefits. Thus, an
alternative to this common protein source in the making of commercial fish feed is
gaining interest among researchers. The replacer or substitute ingredients that could
potentially be used are protein sources from aquatic plants, legumes, cereal byproducts and animal by-products. Interestingly, the most accessible and inexpensive
food component in aquaculture is plant protein sources such as microalgae (Sirakov
et al. 2015).
According to FAO (2019), tilapia can be fed with high percentage of plant proteins.
However, most of these alternative ingredients are deficient of some nutrients and
hence require a combination with other feedstuffs. FAO (2019) also mentioned that
the maximum inclusion limits of each feedstuff that can be used in making tilapia
feeds is dependent on several factors such as the life stages of fish, economic factor
and availability. Besides, the ingredients used in the formulation of tilapia feeds
varies between countries. For example, in Thailand, a common feed formulation
of tilapia fish contains 16% fishmeal, 24% peanut meal, 14% soybean meal, 30%
rice bran, 15% broken rice, vitamin and minerals 1% (Somsueb 1994). In Malaysia,
the commercial tilapia feed ingredients contain 15% fishmeal, 5% meat meal, 20%
soybean meal, 10% groundnut meal, 10% rice bran, 15% wheat middling, 15% corn
or broken rice or cassava, 4% fish oil or vegetables oil, 2% di-calcium phosphate,
2% vitamin premix and 2% mineral premix (FAO 2019).
The reformulation of diets for tilapia with substitution of plant protein source such
as microalgae is an alternative way to maintain the production of feeds. Thus, able to
solve the problem of decreasing resources of fish meal to meet the needs of aquaculture industry (Hemaiswarya et al. 2011). The increasing attention on microalgae for
aquaculture feed is due to its several positive characteristics and because microalgae
are at the base of aquatic food chain where tilapia are adapted to consume. Sarker
et al. (2016) reported that the use of microalgae Schizochytrium sp. improved the
feed utilization efficiency, weight gain and fatty acid profiles in tilapia when the
microalgae are substituted in its diet. Additionally, this formulated diet also provides
high quality and a supplement of long-chain polyunsaturated fatty acids (PUFA) in
N. D. Hairuddin et al.
5.5 Microalgae as an Alternative Protein Source in Fish
Feed
Global production of aqua feeds in 2003 was estimated approximately 19.5 MT
and tilapia feeds contributes for approximately 8.1% of global aqua feed production
in the same year (Tacon et al. 2006). The most common commercial tilapia feeds
are dry sinking pellets and extruded floating pellets (Groenewald 2018). Food and
Agricultural Organization (FAO 2019) reported that under semi-intensive farming
systems, most tilapia farmers used formulated feeds while in intensive pond and tank
culture systems or in cages, tilapia farmers mostly depend on commercial pelleted
feeds. Production of high quality formulated feed needs to be maintained to ensure
high yields and large sized fish within short period of time. Although fishmeal is the
most preferred protein source in formulated feed, the availability and the increasing
price of fishmeal worldwide become more concern compared to its benefits. Thus, an
alternative to this common protein source in the making of commercial fish feed is
gaining interest among researchers. The replacer or substitute ingredients that could
potentially be used are protein sources from aquatic plants, legumes, cereal byproducts and animal by-products. Interestingly, the most accessible and inexpensive
food component in aquaculture is plant protein sources such as microalgae (Sirakov
et al. 2015).
According to FAO (2019), tilapia can be fed with high percentage of plant proteins.
However, most of these alternative ingredients are deficient of some nutrients and
hence require a combination with other feedstuffs. FAO (2019) also mentioned that
the maximum inclusion limits of each feedstuff that can be used in making tilapia
feeds is dependent on several factors such as the life stages of fish, economic factor
and availability. Besides, the ingredients used in the formulation of tilapia feeds
varies between countries. For example, in Thailand, a common feed formulation
of tilapia fish contains 16% fishmeal, 24% peanut meal, 14% soybean meal, 30%
rice bran, 15% broken rice, vitamin and minerals 1% (Somsueb 1994). In Malaysia,
the commercial tilapia feed ingredients contain 15% fishmeal, 5% meat meal, 20%
soybean meal, 10% groundnut meal, 10% rice bran, 15% wheat middling, 15% corn
or broken rice or cassava, 4% fish oil or vegetables oil, 2% di-calcium phosphate,
2% vitamin premix and 2% mineral premix (FAO 2019).
The reformulation of diets for tilapia with substitution of plant protein source such
as microalgae is an alternative way to maintain the production of feeds. Thus, able to
solve the problem of decreasing resources of fish meal to meet the needs of aquaculture industry (Hemaiswarya et al. 2011). The increasing attention on microalgae for
aquaculture feed is due to its several positive characteristics and because microalgae
are at the base of aquatic food chain where tilapia are adapted to consume. Sarker
et al. (2016) reported that the use of microalgae Schizochytrium sp. improved the
feed utilization efficiency, weight gain and fatty acid profiles in tilapia when the
microalgae are substituted in its diet. Additionally, this formulated diet also provides
high quality and a supplement of long-chain polyunsaturated fatty acids (PUFA) in