ANFF topic 2 part 2

Question 1

Why is development of new species-specific diet formulations important for the aquaculture industry?

Answer 1

Satisfy increasing demand for:

• affordability
• safe
• high-quality fish and seafood products

Question 2

What are the types of prepared or artificial feeds?

Answer 2

• Complete

- Supplemental

Question 3

What does the nutritional content of the feed depend on in fish?

Answer 3

• Species of fish

- Life stage of fish

Question 4

Why do aquaculture fish require a complete diet?

Answer 4

• reared in high-density indoor systems/confined in cages

- cannot forage freely on natural food (e.g. algae, aquatic plants, aquatic invertebrates)

Question 5

What are supplemental diets for?

Answer 5

• doused to help fortify the naturally available diet with extra protein, carbohydrate and lipids
• supplemental diets do not contain a full complement of vitamins or minerals

Question 6

What are the 10 essential amino acids that cannot be synthesized by fish?

Answer 6

• Methionine
• Arginine
• Threonine
• Tryptophan
• Histidine
• Isoleucine
• Lysine
• Leucine
• Valine
• Phenylalanine

Question 7

What are limiting amino acids?

Answer 7

• essential amino acids in digested protein that are in the shortest supply relative to body requirements for absorbed amino acids

Question 8

What are the limiting amino acids in fish?

Answer 8

• Methionine

- Lysine

Question 9

What are fish feeds prepared with plant protein low in?

Answer 9

• Methionine

Question 10

What are fish feeds manufactured with bacterial or yeast proteins deficient in?

Answer 10

• Methionine

- Lysine

Question 11

What does providing the dietary protein and specific amino acid requirements for each species do?

Answer 11

• promote optimal growth and health

Question 12

What percentage of aquaculture feeds should be protein for shrimps?

Answer 12

• 30-35%

Question 13

What percentage of aquaculture feeds should be protein for catfish?

Answer 13

• 28-32%

Question 14

What percentage of aquaculture feeds should be protein for tilapia?

Answer 14

• 35-40%

Question 15

What percentage of aquaculture feeds should be protein for hybrid striped bass?

Answer 15

• 38-42%

Question 16

What percentage of aquaculture feeds should be protein for trout/other marine fish?

Answer 16

• 40-45%

Question 17

What are some factors affecting the needs of protein requirements in fish?

Answer 17

• Rearing environment (concrete cages, indoor systems)
• Water temperature
• Water quality
• Genetic composition of fish
• Feeding rates of fish
• Life stage of fish (higher for early life stages)
• Size of fish (higher for smaller fish)
• Diet of fish (higher for carnivores, lower for herbivorous and omnivorous fish)
• Density of environment (higher for fish reared in high-density systems –> e.g. recirculating aquaculture)

Question 18

How much protein is lost to the environment (fish)?

Answer 18

• 65% can be lost

Question 19

What is nitrogen excreted as in fish?

Answer 19

• excreted as ammonia (NH3) from the gills of the fish

- 10% is excreted as solid wastes

Question 20

What can happen if the fish excrete high amounts of ammonia?

Answer 20

Eutrophication of surface waters

• excess nitrogen from fish farm effluents (liquid waste)
• water quality concern for fish farmers

Question 21

What percentage of aquaculture feeds should be lipids for fish?

Answer 21

• 7-15%

Question 22

Why are lipids needed for fish?

Answer 22

• supply essential fatty acids
• serve as transporters for fat-soluble vitamins
• partially spare/substitute protein (reduce high cost of feed; protein highest cost)

Question 23

What happens when there is too much lipids in the diet?

Answer 23

Excessive fat deposition in the liver

• decreased fish health
• decreased quality (humans may not be able to consume)
• Decreased shelf life of the final product

Question 24

What fatty acids do fish typically require?

Answer 24

• Omega-3

- Omega-6 (n-3 and n-6) families

Question 25

What are some sources of omega-3 unsaturated fatty acids?

Answer 25

- marine fish (not sustainable --> fish eat fish) | - algal oils

Question 26

Where are lipids deposited in the fish?

Answer 26

- fish muscle

Question 27

What are some omega-3 foods?

Answer 27

- Salmon fish oil - Cauliflower - Mackeral - Chia seeds - Walnuts

Question 28

What are the 3 omega-3 fatty acids?

Answer 28

- ALA: α-Linolenic acid - EPA: Eicosapentaenoic acid - DHA: Docosahexaenoic acid

Question 29

What are the 3 omega-6 acids?

Answer 29

- LA: Linoleic acid - AA: Arachidonic acid - DPA: Docosapentaenoic acid

Question 30

What omega-3 acid does freshwater fish require?

Answer 30

- APA: α-Linolenic acid | - 0.5-1.5% of dry diet

Question 31

What omega-3 acids do marine fish require?

Answer 31

- EPA: Eicosapentaenoic acid - DHA: Docosahexaenoic acid - 0.5-2% of dry diet

Question 32

Why do marine fish require EPA and DHA while freshwater fish only require APA?

Answer 32

- Freshwater fish can elongate and desaturate linolenic acid using enzyme systems --> results in longer-chain omega-3 fatty acids EPA and DHA - Marine fish typically do not possess these elongation and desaturation enzyme systems --> require long-chain omega-3 fatty acids in their diets

Question 33

Why are carbohydrates used in fish feed?

Answer 33

- least expensive source of energy for fish diets | - reduce feed costs

Question 34

What are the functions of carbohydrates?

Answer 34

- Binding activity during feed manufacturing - useful in the extrusion manufacture of floating feeds - Stored as glycogen --> not used efficiently by fish tho - Fish can use up to about 20% of dietary carbs

Question 35

Why are vitamins required in the fish diet?

Answer 35

- support normal fish growth and health | - not synthesized by fish and must be provided in the diet

Question 36

What are some water-soluble vitamins?

Answer 36

- B vitamins (thiamine, riboflavin, folic acid) - Inositol - Choline - Vitamin C (ascorbic acid) --> powerful antioxidant; enhances immune system of fish & shrimp; inhibit dietary lipid oxidation (impove shelf life)

Question 37

What are some fat-soluble vitamins?

Answer 37

- Vitamin A (retinol, beta-carotene) - Vitamin D (cholecalciferol) - Vitamin E (tocopherols) --> antioxidant; inhibit dietary lipid oxidation --> improve shelf life

Question 38

What happens when there is a deficiency of vitamins?

Answer 38

- reduced growth

Question 39

What happens when there is ascorbic acid and folic acid deficiencies (vitamin C and vitamin B)?

Answer 39

- scoliosis (bent back syndrome) | - dark colouration

Question 40

Why do fish require minerals?

Answer 40

- inorganic elements - normal body functions - fish can absorb many minerals directly from the water through the gills and skin

Question 41

What are some common dietary macrominerals?

Answer 41

- Calcium - Sodium - Chloride - Potassium - Phosphorus - Magnesium

Question 42

What are the functions of macrominerals?

Answer 42

- regulate osmotic balance | - bone formation and integrity

Question 43

What are some common dietary microminerals

Answer 43

- iron - copper - chromium - iodine - manganese - zinc - selenium

Question 44

What are the functions of microminerals?

Answer 44

- components in enzyme and hormone systems

Question 45

How should an optimum diet be created?

Answer 45

- ratio of protein to energy must be determined independently for each fish species - note that excess energy relative to protein content in the diet can result in high lipid deposition

Question 46

What happens if the diet has excessive energy levels?

Answer 46

- decreased feed intake | - reduced weight gain

Question 47

What happens if the diet has inadequate energy content?

Answer 47

- reduced weight gain | - cannot satisfy energy requirements for growth