162 Marine Macro- and Microalgae: An Overview
the feed that present a benefit above and beyond fulfilling the basic nutritional needs). Such capacity
is extremely important, since the feed industry is constantly searching for ingredients that could add
value to their traditional feeds during sensitive periods of the production cycle, or specific situations
resulting from farming practices. Sensitive periods of the aquaculture production cycle where functional
ingredients could be highly valued are early feeding stages, specific physiological stages (e.g., high
stressful conditions), and finishing stages (for enhancement of quality criteria). In land-based animals,
critical periods of development include piglets and calves weaning phase, egg productivity/quality in
laying hens, milk yield and productivity in dairy cows, and recovery after stressing conditions for athletic
animals (e.g., race horses) (Dias and Sendão unpublished data). Due to their composition, digestibility,
and lack of toxicity, the introduction of microalgae meal can thus target specialty feed applications, apart
from the nutritional commodities market.
Besides the nutritional improvement that microalgae incorporation in feeds may bring to animals
health, they are the only biomass material that allows daily harvest production during all the year,
an advantage that ensures a constant supply of raw materials to the feed market. In fact, microalgae
biomass can be produced in large-scale bioreactors, under straight controlled conditions, so that desired,
customer-specific, active components are produced. Thus, biomass can be manufactured to a consistent,
standardized quality, reproducible during the whole year, irrespective of location, weather and climatic
conditions, and without the seasonal variation typically associated with cultivated plants. Furthermore,
microalgae also possess advantages in terms of productivity, when compared with higher plants.
Animal nutritional requirements
Feeds are a blend from various raw materials and additives, formulated according to the specific
requirements of the target animal, and manufactured as meal type, pellets, or crumbles. The nutritive
value of a diet is directly related with its ingredients constitution (Wondra 1995; McDonald 2002).
Animals need a variety of nutrients to meet their basic needs. These nutrients generally include
lipids and carbohydrates to supply energy, proteins that provide amino acids, vitamins used as co-factors
for enzymes and other functions, and specific compounds to fulfil specific needs. Depending on the
amounts needed, they can be categorized as either macronutrients (needed in relatively large amounts)
or micronutrients (needed in smaller quantities). The former includes carbohydrates, fats, fibre, proteins,
and water, whereas the later comprise minerals and vitamins (Freeman 2003).
Macronutrients
Carbohydrates
Carbohydrates in plants can be divided into those that serve as storage and energy reserves, available for
metabolism (e.g., sugars, starch, pectin, and some cellulose in barley grain) and those that are structural
(e.g., fibrous cellulose, hemi-cellulose, and lignin in straw). Carbohydrates are a major source of energy
in livestock feeds (Anonymous 2006). The main functions of this nutrient mainly comprise energy
supply (to power muscular movement), body heat, and building block for other nutrients. Carbohydrates
utilization by animals depend on their digestion system, although its dietary excess is always stored as
fat. Simple stomached animals cannot digest large amounts of fibre, and their ration must be made up
of mostly cereal grains. Ruminant animals can eat large amounts of fibre, and a high percentage of their
ration is roughage.
Lipids
Lipids (fats or oils), like carbohydrates, are neutral chemical compounds essentially composed of carbon,
hydrogen, and oxygen, although they contain more carbon and hydrogen atoms than carbohydrates.
Concomitantly, fats provide 2.25 times more energy per gram than carbohydrates. Their main functions
include energy supply, heat maintenance, body protection, fat-soluble vitamins carrying, and immune
the feed that present a benefit above and beyond fulfilling the basic nutritional needs). Such capacity
is extremely important, since the feed industry is constantly searching for ingredients that could add
value to their traditional feeds during sensitive periods of the production cycle, or specific situations
resulting from farming practices. Sensitive periods of the aquaculture production cycle where functional
ingredients could be highly valued are early feeding stages, specific physiological stages (e.g., high
stressful conditions), and finishing stages (for enhancement of quality criteria). In land-based animals,
critical periods of development include piglets and calves weaning phase, egg productivity/quality in
laying hens, milk yield and productivity in dairy cows, and recovery after stressing conditions for athletic
animals (e.g., race horses) (Dias and Sendão unpublished data). Due to their composition, digestibility,
and lack of toxicity, the introduction of microalgae meal can thus target specialty feed applications, apart
from the nutritional commodities market.
Besides the nutritional improvement that microalgae incorporation in feeds may bring to animals
health, they are the only biomass material that allows daily harvest production during all the year,
an advantage that ensures a constant supply of raw materials to the feed market. In fact, microalgae
biomass can be produced in large-scale bioreactors, under straight controlled conditions, so that desired,
customer-specific, active components are produced. Thus, biomass can be manufactured to a consistent,
standardized quality, reproducible during the whole year, irrespective of location, weather and climatic
conditions, and without the seasonal variation typically associated with cultivated plants. Furthermore,
microalgae also possess advantages in terms of productivity, when compared with higher plants.
Animal nutritional requirements
Feeds are a blend from various raw materials and additives, formulated according to the specific
requirements of the target animal, and manufactured as meal type, pellets, or crumbles. The nutritive
value of a diet is directly related with its ingredients constitution (Wondra 1995; McDonald 2002).
Animals need a variety of nutrients to meet their basic needs. These nutrients generally include
lipids and carbohydrates to supply energy, proteins that provide amino acids, vitamins used as co-factors
for enzymes and other functions, and specific compounds to fulfil specific needs. Depending on the
amounts needed, they can be categorized as either macronutrients (needed in relatively large amounts)
or micronutrients (needed in smaller quantities). The former includes carbohydrates, fats, fibre, proteins,
and water, whereas the later comprise minerals and vitamins (Freeman 2003).
Macronutrients
Carbohydrates
Carbohydrates in plants can be divided into those that serve as storage and energy reserves, available for
metabolism (e.g., sugars, starch, pectin, and some cellulose in barley grain) and those that are structural
(e.g., fibrous cellulose, hemi-cellulose, and lignin in straw). Carbohydrates are a major source of energy
in livestock feeds (Anonymous 2006). The main functions of this nutrient mainly comprise energy
supply (to power muscular movement), body heat, and building block for other nutrients. Carbohydrates
utilization by animals depend on their digestion system, although its dietary excess is always stored as
fat. Simple stomached animals cannot digest large amounts of fibre, and their ration must be made up
of mostly cereal grains. Ruminant animals can eat large amounts of fibre, and a high percentage of their
ration is roughage.
Lipids
Lipids (fats or oils), like carbohydrates, are neutral chemical compounds essentially composed of carbon,
hydrogen, and oxygen, although they contain more carbon and hydrogen atoms than carbohydrates.
Concomitantly, fats provide 2.25 times more energy per gram than carbohydrates. Their main functions
include energy supply, heat maintenance, body protection, fat-soluble vitamins carrying, and immune