Atillano, Nigel Kieth F.
BS Fisheries - 3
IMPORTANT OF FISH NUTRITION
Assessment: Answer the following questions as concise as possible. Each
item corresponds to 5 points.
1. What are the important roles of Fish Nutrition in the sustainable
development of aquaculture?
Answer: There are three main important roles of Fish Nutrition in the
sustainable development of aquaculture. First, The efficient conversion
of feed to fish is important to fish farmers because feed is the largest
component of the total cost of Secondly, Improved feed composition
and better feed efficiency will result in higher fish production, lower
feed cost, and low waste production hence, decreased nutrient load
from fish farming. Lastly, Good quality feed coupled with appropriate
feeding management has been shown to result in improved feed
conversion efficiency, lower costs of production, and reduced levels of
environmental degradation.
2. What are the important issues in feed development and feeding that
need to be considered in making aquaculture sustainable for future
generations?
Answer : In order to ensure that a feeding program is effective, the
following aspects need to be considered:
Consider the basic principles of fish nutrition and feeding;
Understand the nutrient requirements of cultured species, their
feeding habits and behavior, and the ability of fish to digest and
utilize essential nutrients;
Aquafeeds must satisfy the nutrient requirements of the cultured
species in terms of protein essential amino acids, lipid and
essential fatty acids, energy, vitamins, and minerals;
The nutrient requirements should be known for a specific fish
species intended for culture. For example, the protein
requirements of an omnivore like milkfish and a herbivore like
tilapia are generally lower than those of carnivores like grouper,
sea bass, and snapper.
Fish species also differ in their requirements for essential amino
acids. Milkfish requires n-3 fatty.
Acids while Asian sea bass and tiger shrimp need both n-3 and n-
6 fatty acids. In contrast, tilapia requires n-6 fatty acids. Thus,
feed formulations should be based on the requirement and levels
of essential nutrients that are optimal for the cultured species.
The quality of the feed will ultimately depend on the level of
available nutrients for fish. Because fish eat to satisfy their
energy requirement, the energy value of the feed will affect its
efficiency. Nutrients in the body are in dynamic equilibrium,
hence, a deficiency or over supply of one will.
Affect the others. The study of nutrition is interrelated with allied
arts and sciences. Nutrition is also an art because there is no
single approach to meeting the needs of the animal.
ESSENTIAL NUTRIENTS
Assessment
1 . Name the ten essential amino acids required by fish.
Answer: arginine, histidine, isoleucine, leucine, lysine, methionine,
phenylalanine, threonine, tryptophan, and valine.
2. The following graph shows the growth response of tiger shrimp fed graded
levels of phenylalanine for 8 weeks as described by the quadratic regression
model.
Question
a. In the above graph, what method was used to determine qualitative
amino acid requirements of tiger shrimp?
Answer : Assumption method
b. What is the percentage requirement of phenylalanine?
Answer: 1.4%
c. Describe a dose-response curve used to determine the quantitative
amino acid requirement.
Answer : Quantitative method assumes that weight gain is linearly
related to increasing dietary levels of the essential amino acid at or below
the experimental diets is then prepared containing graded levels of one
amino acid for which the requirement is requirement level. When the
requirement is met, weight gains abruptly plateau and then decline if the
dietary concentration of the nutrient exceeds the animal's tolerance of
one amino acid for which the requirement is requirement level. When the
requirement is met, weight gains abruptly plateau and then decline if the
dietary concentration of the nutrient exceeds the animal's tolerance.
FEEDING HABITS AND DIGESTIVE PHYSIOLOGY OF FISH
Feeding habit of milkfish
Answer: Microphagous
1. Key factor in determining what the fish will eat.
Answer: Food availability
2. Begins at the posterior edge of the gills and includes the
esophagus and stomach.
Answer: Foregut
3. Relative gut lengths of omnivores.
Answer : 0.6-8.0
4. An extension of the midgut
Answer: hindgut
5. An enzyme that is activated in the intestine by enterokinase, an
enzyme secreted from the intestinal mucosa Answer:
Trypsinogen
6. Most common method of measuring digestibility that add to the
diet a market such as chromic oxide.
Answer: In vivo method
7. A method in estimating protein digestibility that incubate test
rations with intestinal extracts of fish at an optimum temperature
for a specified length of time.
Answer: In vitro assays
8. Level of Unionized ammonia (NH3) that inhibits growth in most
species.
Answer: 0.1 ppm
9. A process whereby ingested food nutrients such as proteins,
lipids, and carbohydrates are broken down into units that are
small enough to be absorbed across the gut wall.
Answer: Digestion
