Aquatic Animal Nutrition
FAS 2240C
Lecture 1: Introduction
Course Syllabus
Study of aquatic animal nutrition:
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bioenergetics
digestion/digestive anatomy/metabolism
nutrient classes/sources/requirements
formulation/feedstuffs
manufacturing processes
practical pond feed management
Syllabus
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Animals covered: variety of finfish and crustacean species
textbook: none are current or adequate
also, various reprints of peer review journal articles
on reserve:
 De Silva, S.S., and T.A. Anderson, 1995. Fish nutrition in
aquaculture
 Lovell, T., 1989. Nutrition and feeding of fish
 D’Abramo, Conklin and Akiyama, 1992. Crustacean
Nutrition
 Halver, J., 1988. Fish Nutrition
 Maynard and Loosli, 1969. Animal Nutrition
Today’s Lecture: 8/25/05
 Part 1: Introduction
 What is nutrition???
 History of nutrition
 Nutrition today
 Nutrient essentiality
 Part
(Maynard et al.; Lovell)
2: The animal body and its food
(Maynard, et al.; Lovell)
 Aquatics vs. terrestrials
What is Nutrition?
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Nutrition: the provision of all indispensable nutrients in
adequate amounts to insure proper growth and maintenance
of body functions
involves various chemical reactions and physiological
transformations which convert foods into body tissues and
activities
involves ingestion, digestion and absorption of various
nutrients
transport into cells
removal of unusable elements and waste products of
metabolism
History of Nutrition I.
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Lavoisier is generally credited as being the “father”
of nutrition
until the first quarter of 19th Century, we thought
the nutritive value of food resided only in one
component
near the end of the 19th Century research started to
focus primarily on the need for protein, lipids and
carbohydrates
minerals were considered important, but their
essentiality was unknown
History of Nutrition II.
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Tremendous expansion in the 20th Century with the
discovery of vitamins, role of amino acids, more
minerals
the body is now known to need more than 40 nutrients
for normal growth and maintenance
what have been the reasons for these advances???
Human nutritional/health problems
also, basic studies of the functioning of the animal
organism supplemented research
History of Nutrition III.
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Example of historical nutritional research:
heifers fed wheat-based diets produced calves at lower
rates than those fed corn diets
assumption: something toxic in wheat
analysis: nothing toxic in tissues
reality: vitamin deficiency
scientific methods for formulating feeds were
inadequate
research diets eventually simplified/purified
History of Nutrition IV.
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First vitamin discovered in 1913
pioneer nutritional work achieved primarily through the use of
animal subjects
same today, but with restrictions
rats  vitamins, amino acids, minerals
dogs  insulin, nicotinic acid
guinea pigs  prevention of scurvy
chicks  thiamin and other vitamins
bacteria  growth factors, nutrient function in metabolism
final answers must be derived from species studied
Nutrition Today
Animal nutrition today is multidisciplinary:
 metabolism: physiologists, biochemists
 vitamins: organic chemists
 isotopes/chromatography: physicists
 protein structure: molecular biochemists
 breed variation: geneticists
 vitamins/amino acids: microbiologists
 additives/improved digestibility: food technologists
Issue: Overexpansion
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Everyone now-a-days appears to be an expert in nutrition
infomercials, algae, diet fads
claims of superiority without scientific evidence (science vs.
pseudoscience)
example: massive doses of vitamins are useless, often toxic
nutrition industry might need to become more
conservative
it’s no wonder why the average consumer is puzzled!!
Nutrient Essentiality
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essential nutrient: one that must be provided in the diet in order
to insure adequate growth and maintenance, indispensable
Nutrient categories: macro and micro
macronutrients: protein, lipid, carbohydrate, etc.
micronutrients: trace metals, vitamins
important: molecular weight is not the basis, requirement level is
proteins: g/kg vitamins: µg/kg
large requirement doesn’t imply greater importance (example:
B12 in some fish 0.4 µg/day)
Basic Nutritional Concepts
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Animal nutrition is tied back to food crops and ultimately
to the nutritive value of soil
strong interrelationship between human and animal
nutrition
foods/feeds of both contain similar nutrients
metabolic processes are basically similar
nutritional niche of animals: animals concentrate nutrients
of food crops into more nutritious and palatable forms for
humans
point: animals take sources unsuitable for humans
and improve their quality for us!
Animals as Primary Consumers
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Animals produce meat, milk, etc. on land that is often
unsuitable for production of food crops
problem: overall land availability vs. protein demand
fisheries flat, agriculture barely keeping up
nutrition has greatly improved production capacity,
however it is not going to be enough
What Does it All Mean?
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We already know that agriculture is barely
keeping up with world food demand and...
Fisheries are being improperly managed to
the point of steady state
Either we must quickly apply Iowa corn field
technology to all arable land on Earth or food
must be found from other sources
One possible option is aquaculture.
Current Challenges/Problems
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For aquaculture to contribute more to the world’s
food supply, production must be intensified
higher yields must be achieved in ponds
better and more predictable natural sources of
nutrition (natural productivity) must be available (too
unpredictable)
more crude feed materials used as supplements or
compounded feeds must provide all nutrients
retention vs. digestibility: Which is best metric?
Part 2: The Animal Body and Its
Food
From: Lovell and Maynard, et al.
Learning Objectives
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Aquatics, compared to terrestrials, are typically
better converters of nutrients into body tissue.
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This does not apply in all cases to all nutrients.
Aquatics vs. Terrestrials:
feeding issues
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Aquatics are what they are: submerged in water
Guess what?? The water itself can serve as a source of
nutrition (natural productivity). Examples?
Overfeeding of land animals does not necessarily imply ruining
of their environment
In water, nutrients are quickly “lost” if feed is not immediately
consumed
Waste is not readily observable, thus, attraction and palatability
of aquatic feeds is important.
Aquatics vs. Terrestrials:
nutrient requirements
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Overall qualitative (which nutrients) requirement is generally
similar between land and aquatic animals.
Energy requirements are lower for fish than most terrestrials 
higher protein: energy ratio.
Marine species require some fatty acids and sterols that terrestrials
don’t.
Aquatics have reduced dietary mineral requirement (environment
is nutrient source)
Some fish/most crustaceans have limited ability to synthesize
ascorbic acid
Shrimp cannot synthesize cholestrol.
Aquatics vs. Terrestrials:
nutrient requirements
Nutrient requirements for one group of finfish or
crustaceans can only serve as a starting point for
other species
 Lysine example.
 Nutrient requirements will ultimately become more
and more refined
 Problem: apparent vs. true requirement
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Aquatics vs. Terrestrials:
Which protein is better?
fish convert practical feeds into
body tissue more efficiently than
do farm animals
catfish fed compounded rations
gain approximately 0.84 g of
weight per gram of practical diet
(Lovell, 1989)
Why? they are able to assimilate
diets containing higher
percentages of protein
Also, they have a lower dietary
energy requirement (thus, most
protein goes to growth)
% conversion
100
catfish
chicken
cattle
80
60
40
20
0
animal type
Aquatics vs. Terrestrials
however, dietary protein
conversion to body protein
by chickens is similar to
fish
fish don't convert food
more efficiently, it's just
that they get more out of
the protein they consume
advantage: lower energy
cost of protein gain, not
superior food conversion
efficiency
Pro gain/g Pro consumed
0.4
catfish
chicken
cow
0.3
0.2
0.1
0
animal type
Pro gain/Mkcal ME consumed
50
catfish
chicken
cow
40
30
20
10
0
animal type
Aquatics vs. Terrestrials
problem: the total energy budget for production of
protein from fish culture systems hasn't been well
investigated
ponds seem to be similar to that needed for broiler
chicken production
i.e., chickens need heating and ventilation, fish need
water exchange/aeration
thus, if fossil fuel requirements for production
(largely associated with transport, processing) are
similar, fish are your overall more energy-efficient
sources of protein
Fish vs. Farm Animals:
nutritional value
percentage of edible lean
tissue in fish is appreciably
greater than that in beef,
pork or poultry
however, due to low fat, the
caloric value of dressed fish is
less than that of beef or pork
net protein utilization is about
the same as that of red beef
(83 vs 80; 100 for eggs)
% of dressed as lean tissue
100
catfish
beef
pork
chicken
80
60
40
20
0
animal type
food energy (kcal/100 g edible tissue)
160
catfish
beef
pork
chicken
140
120
100
80
60
40
20
0
animal type
Aquatics vs. Terrestrials:
nutritional value
fish, as with other animal flesh, is a good
source of most nutrients
exception: calcium, vit A, vit C
one 8 oz. hamburger patty or fillet each
provides 100% of the RDA for protein,
niacin, vitamin B12 and phosphorus
at same time, though, the fish would only
contain 280 calories as compared to the
burger with 750 calories
Animal Classifications:
we as humans are omnivorous
we eat food from both vegetable and animal
sources
other omnivores: pig, rat, shrimp
herbivores are those animals that live largerly on
vegetable or plant sources of nutrition
examples: ruminants (cattle, rabbits, horses),
tilapia
omnivores and herbivores contribute most to the
human food supply
carnivores aren't much of an influence
Composition of the Animal
Body
if we are consumers of omnivores and
herbivores, we are concerned with what
nutrients they contain
what is the nutritional composition of the animal
body?
original work on determining body composition of
farm animals of various age and nutrient status
impetus: human health and combating of disease
as a result, we now have a large amount of
information on this subject
Percent Composition of the
Animal Body
Species
calf, new
calf, fat
steer, thin
steer, fat
pig, 8kg
pig, 30 kg
pig, 100 kg
horse
human
mouse
guinea pig
Water
74
68
64
43
73
60
49
61
60
66
64
Protein
19
18
19
13
17
13
12
17
18
17
19
Fat
3
10
12
41
6
24
36
17
18
13
12
Ash
4.1
4.0
5.1
3.3
3.4
2.5
2.6
4.5
4.3
4.5
5.0
Percent Composition of Aquatics
Animal
Water
Protein
Fat
Ash
Channel
catfish,
muscle
Artemia
nauplii
77.30
16.30
5.40
1.10
89.09
6.29
1.40
1.02
White
shrimp
90.00
7.17
0.50
1.30
Water and Organic
Substances
Table 2-1 indicates that body composition
for species varies with age and nutritional
state
by nutritional state, we mean fat or thin
it can also be applied to pregnant or, in the
case of crustaceans, molt status
age affects body composition largely by
decreasing water content
this is especially true in very early age
Age vs. Water and Fat
Content
embryo: 95%, shortly after conception
embryo: 75-80%, at birth
calf: 66-72%, at five months
mature: 40-65%
variations in water content of growing
animals are largely due to the storage of fat
as animals grow, they have a tendency to
store fat (depending upon feed intake)
fat displaces water
Distribution of Protein, Lipid,
COH
proteins are found in every cell of the body
besides water, they are the principle constituent of
the body
organs, muscle, tendons, connective tissue
fat is localized in adipose tissue, fat depots under the
skin, around the intestines/other organs
it is also present in muscles, bones, etc.
very small amount of carbohydrates are found in liver,
muscles, and blood (constantly being used for energy
or re-formed)
The Blood
from a nutritional standpoint, the
composition of the blood is very important
it is the medium by which oxygen and
nutrients are transported to various tissues
it is the means whereby waste products of
metabolism are removed (kidneys)
it comprises 5-10% of body weight and varies
by species, body weight, nutritive state
The Blood (continued)
total blood volume really varies due to the
amount of active tissue a body has
as mentioned, the solid matter of blood
(corpuscles) consists almost entirely of the
iron-containing protein, hemoglobin
hemoglobin is used to transport oxygen
for most crustaceans, the O transport protein is
2
hemocyanin (Cu)
some crustaceans use pinnaglobulin, which has
manganese (Mn) at its center
Muscle and Other Tissues
movement of the body, organs and tissues
require muscle action
thus, we have muscles distributed
throughout the body
1/2 the body is composed of skeletal muscle
(75% water, of the dry matter, 75-80% is
protein)
the remainder of muscle tissue is largely fat,
COH (glycogen), minerals
Muscle and Other Tissues
(continued)
epithelial tissue (skin, hair, feathers, lining of the
various tracts) are largely composed of keratin
this type of protein is arranged differently from
other proteins and is highly insoluble or digestible
connective tissue (cartilage, tendons, ligaments,
bone matrix) consists primarily of insoluble
collagen (protein)
nervous tissue is primarily composed of complexes
of lipid, COH, protein
Estimation of Body
Composition
body composition information provides
information on the stage of development and
nutrition of animals
you can't simply weigh the animal to determine
this
animals must be slaughtered and analyzed
chemically, usually combined with feeding
experiments
unfortunately the animal can be used only once,
changes can't be determined
For Next Time…
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Quiz 2: Environmental Factors
Topic 3: Digestive Physiology, Nutrient Digestability (What
happens to the food fish eat?)
Handouts, Lovell (1989).