fish nutrition

Question 1

what are the advantages of the aquaculture industry

Answer 1

• highest protein retention ration
• lowest feed conversion ratio
• lower greenhouse gas emissions
• more meat/per unit feed consumed

Question 2

tropical fishes

Answer 2

• warm water (23-26C)
• tilapias

Question 3

warmwater fishes

Answer 3

• wide temp range
• poor growth below 10-15C
• carp

Question 4

coldwater fishes

Answer 4

• not tolerate temp above mid-twenties
• salmon, trout, char

Question 5

carnivore ex

Answer 5

rainbow trout

Question 6

omnivore - animal based ex

Answer 6

channel catfish

Question 7

omnivore - plant based ex

Answer 7

carp

Question 8

herbivore ex

Answer 8

milk fish, tilapia

Question 9

what are the 4 main differences between fish nutrition and mammals

Answer 9

1. energy requirements of fish are lower - superior feed efficiency
2. VC is synthesized poorly or not at all by most fish
3. most fish require n-3 fatty acids (warm blooded animals need n-6)
4. fish can absorb soluble minerals from the water

Question 10

what are the essential fatty acids

Answer 10

• linoleic (n-6)
• linolenic (n-3) - fish require omega 3 FA

Question 11

why do fish have lower energy requirements

Answer 11

1. fish have a low basal energy need b/c they don’t expend energy to maintain body temp ( 3-5% of ME in trout; 30% of ME in mammals)
2. fish have a low energy need for locomotion and voluntary activity
3. fish use less energy for protein catabolism and the excretion of N (ammonia is end product in fish)

Question 12

are CHO a major source of energy in fish

Answer 12

no

Question 13

primary sources of CHO in fish feeds include:

Answer 13

• cereal grains
• wheat by-product
• cooked starches

Question 14

what is the GE from CHO available to mammals and trout

Answer 14

4.15 kcal/g; 1.60 kcal/g

Question 15

what is the max CHO level of salmonid diets

Answer 15

12-20%

Question 16

what is the max CHO level in catfish and carp

Answer 16

25%

Question 17

why feed CHO to fish

Answer 17

• cheap energy source
• use of CHOs for energy to save protein for other purposes (protein sparing effect)

Question 18

why do fish require an n-3 double bond position

Answer 18

• omega-3 FA
• necessary for membrane phospholipids to maintain flexibility and permeability at low temperatures

Question 19

what do primary sources of energy in fish have

Answer 19

a protein-sparing effect

Question 20

what is fat content in fish influenced by

Answer 20

• diet
• species
• environment

Question 21

what can excessive fat levels in feed do

Answer 21

hemper pelleting and cause spoilage if not protected with antioxidants

Question 22

what do protein requirements change based on

Answer 22

• fish trophic level
• water salinity
• inversely related to rearing temp

Question 23

fish meal

Answer 23

• highest quality
• rich source of energy and minerals
• palatable
• high cost

Question 24

soybean meal

Answer 24

• high amino acid profiles
• unpalatable
• anti-nutritional factors such as trypsin inhibitors

Question 25

cottonseed meal

Answer 25

* good source of protein * low available lysine content * **free gossypol - toxic**

Question 26

meat and bone meal

Answer 26

* good source of protein * **may not be palatable**

Question 27

soybean meal in salmon/trout feed

Answer 27

* poor palatability * antinutritional factors - **enzyme additives** (saponins, lectin, trypsin inhibitor)

Question 28

canola meal in salmon/trout feed

Answer 28

high in fiber and phytic acid

Question 29

corn gluten meal in salmon/trout feed

Answer 29

* adds fiber * color fish flesh yellow (limited to 5% inclusion in the US)

Question 30

wheat gluten meal in salmon/trout diets

Answer 30

too expensive

Question 31

what are the vitamin requirements in fish

Answer 31

* four fat soluble vitamins * eleven water soluble vitamins

Question 32

what are the mineral requirements in fish

Answer 32

* fish have the ability to absorb minerals across gills and skin * require all of the macro and micro elements required by other animals

Question 33

what are chemical factors affecting water quality

Answer 33

* phytoplankton and dissolved oxygen changes * pH changes in response to bicarbonate flux * pH and temperature interactions on unionized - NH3

Question 34

when to feed fish

Answer 34

* when oxygen is high and support the higher activity * not be fed at night b/c fish's increased oxygen requirement at 4-8hrs after eating, will coincide with low dissolved oxygen in water * feed directly into water - feed must be consumed within a certain time or it will go to waste * some fish prefer feed that floats or sinks * low input systems, fertilize the pond to stimulate phytoplankton production to increase feed supply

Question 35

what are the different systems

Answer 35

* pond * raceway * recirculation * partitioned aquaculture * integrated muli-trophic aquaculture