Seaweeds: A Promising Source for Sustainable Development - Environmental Sustainability: Role of Green Technologies - page 77

polyunsaturates also have much lower melting
points than monounsaturates or saturates; thus,
algal biodiesel should have much better cold
weather properties than many other bio-oils
(Demirbas 2008 ). A large amount of microalgal
oil was effi ciently extracted from the heterotro-
phic cells using n-hexane and then transmuted
into biodiesel by acidic transesterifi cation (Xu
et al. 2006 ).

fi nely ground seaweed meal made from brown
seaweeds is cheaper.
There is also a market for fresh seaweed as a
feed for abalone. In Australia, the brown seaweed
Macrocystis pyrifera and the red seaweed
Gracilaria edulis have been used. In South
Africa, Porphyra is in demand for abalone
feed, and recommendations have been made for
the management of the wild population of the
seaweed. Pacifi c dulse ( Palmaria mollis ) has
been found to be a valuable food for the red
abalone, Haliotis rufescens , and development of
land-based cultivation has been undertaken with
a view of producing commercial quantities of the
seaweed. The green seaweed, Ulva lactuca , has
been fed to Haliotis tuberculata and H. discus
(McHugh 2003 ). Feeding trials showed that aba-
lone growth is greatly improved by high protein
content, and this is attained by culturing the
seaweed with high levels of ammonia present.

9 Seaweeds Used

as Animal Feed

Seaweeds had been used for many years directly
for human consumption and animal feed. It is
also an ingredient for the global food and cosmet-
ics industries and is used as fertilizer and as an
animal feed additive. Also, seaweeds are valuable
sources of food, micronutrients, and raw materi-
als for the pharmaceutical industry. Seaweed has
plenty of essential nutrients, especially trace
elements and several other bioactive substances
that explains why seaweeds are considered as a
food supplement in the twenty-fi rst century and
as source of proteins, lipids, polysaccharides,
mineral, vitamins, and enzyme (Rimber 2007 ).
Interestingly, the best known component of the
seaweed-derived industry is that of the phycocol-
loids, the gelling, thickening, emulsifying, bind-
ing, stabilizing, clarifying, and protecting agents
known as carrageenans, alginates, and agars
(Chopin 2007 ). Total annual use by the global
seaweed industry is about 8 million tones of wet
seaweed (McHugh 2003 ).

9.2 Seaweed Used as Feed

for Farm Animals

Seaweeds are cheap sources of minerals and trace
elements besides vitamins, growth hormones,
and phycocolloids. Hence, meals prepared from
seaweeds can be given as supplements to the
daily rations of the cattle, poultry shrimps, and
fi shes. Seaweed meal can be mixed with fi sh
meal and used as poultry feed. Dave et al. ( 1977 )
assessed the possibility of seaweeds being used
as supplementary animal feed and they reviewed
the feeding trails of animals with seaweeds
conducted in Japan, Germany, the UK, Norway,
and other countries.

9.1 Seaweed Used as Fish Feed

9.3 Seaweed Utilization

in Integrated Aquaculture

In fi sh farming, wet feed usually consists of meat
waste and fi sh waste mixed with dry additives
containing extra nutrients all formed together in a
doughy mass. When thrown into the fi shponds or
cages, it must hold together and not disintegrate
or dissolve in the water. A binder is needed;
sometimes a technical grade of alginate is used.
It has also been used to bind formulated feeds
for shrimp and abalone. However, the use of

Cultivation of Gracilaria started in Taiwan
Province of China in the 1960s as a source of raw
material for its agar industry. At fi rst cultivation
was on ropes in ditches containing fi shpond effl u-
ents, but in 1967, it was moved into the fi shponds
themselves. This had the twofold benefi t of the