Fish Nutrition Research Differences and similarities with livestock nutrition and what the future holds. Part I.

1
Fish Nutrition Research Differences and
similarities with livestock nutrition and what
the future holds. Part I.

• Ronald W. Hardy, Director
• Aquaculture Research Institute
• University of Idaho

2
Topics to cover

• Differences between fish and livestock
• Brief history of fish nutrition
• Brief overview of evolution of fish feed
  manufacturing
• Todays hot topics in fish nutrition
• Replacement of marine protein and oils
• Effects of nutrition on food quality and fish
  health
• Microparticulate feeds for small fish larvae at
  first feeding
• Opportunities presented by developments in
  molecular biology

3
Fish Facts

• Fish evolved in a very diverse environment, and
  20,000 species exploit every possible niche
• Currently, there are 140 species fish being
  farmed
• First publication on fish farming was 2500 BC
• In 2005, 43 of all fish consumed globally was
  produced by farming
• Aquaculture production growing at 9-10 annually,
  fastest sector of animal production

4
Differences among farmed fish species

• Marine, brackish and freshwater fish
• Differences in osmotic cost to maintain
  homeostasis
• Coldwater and warmwater fish
• O2 content in water, plus availability of natural
  food in ponds compared trout raceways or marine
  net-pens
• metabolic rate and temperature tolerances
• membrane fluidity that influences fatty acid
  requirements
• Fish and crustaceans (shrimp, crabs)
• Huge differences in mechanisms of locating feed
• Shrimp are external masticators, fish gulp feed
• Differences in digestive physiology
• Feeds must be water-stable for slow eaters like
  shrimp

5
Fish vs. livestock and poultry

• Major differences associated with aquatic
  existence
• Fish maintain neutral buoyancy and do not need
  skeletal and muscular systems to oppose gravity
• Fish excrete ammonia
• Fish are cold-blooded
• Other differences
• Fish exhibit indeterminate growth
• Huge differences in digestive system among farmed
  fish
• Fish are monogastric, but
• Gastric stomached fish (carnivores like
  salmon/trout)
• Agastric (carp)

6
(No Transcript)
7
Fish vs. livestock and poultrydifferences
associated with aquatic existence

• Fish exist in neutral gravity, no need for heavy
  skeleton
• Dietary calcium and phosphorus needs are lower
• Energy expenditures for locomotion are lower
• Fish excrete ammonia via the gills
• Lower metabolic cost than excreting urea or uric
  acid
• Higher caloric energy yield from metabolism of
  amino acids
• Fish are cold-blooded
• Upside no need to stay warm
• Downside rates of metabolism, digestion, etc.
  decrease in cooler water, plus membrane fluidity
  must change

8
Fish vs. livestock and poultrydifferences in
physiology

• Many fish exhibit indeterminate growth
• Growth continues after first maturation and
  spawning
• Hypertrophy and hyperplasia (make new muscle
  cells)
• Fish are monogastric (few herbivorous fish)
• Some fish have an acid stomach
• Other start with an acid stomach, then lose it as
  fingerlings
• Some are stomach-less (agastric)

9
Fish vs. livestock and poultrydifferences at
start of exogenous feeding

• Some fish spawn large eggs
• Salmon trout (2000-15,000 eggs/female)
• Incubation requires 50-100 days depending on
  water temperature
• First feeding fry are 200-400 mg and can be fed
  small, particulate feed
• Many fish spawn very small eggs
• Most marine species (gt 1 million small eggs per
  female)
• Incubation requires 3-7 days
• First feeding fry are very small and must be fed
  live-feed through metamorphosis or until reach a
  decent size
• It is very challenging to provide adequate
  nutrition via live feed
• Right live feed at the right time
• Correct nutritional content of live prey ( need
  PUFA enrichment)

10
Cod eggs
11
Copper rockfish larvae at first feeding
12
Canary rockfish larvae with feed in gutsix weeks
after first feeding stage
13
Fish vs. livestock and poultryother nutritional
differences

• Fish nutritional requirements
• Ascorbic acid
• Polyunsaturated fatty acids (PUFAs)
• Many minerals obtained via the water
• Carnivorous species have a limited ability to
  utilize or metabolize starch
• They evolved using protein and lipid for
  metabolic energy

14
Efficiency of fish compared to livestock

• FCR values less than 1.0 for fish
• FCR values 1.6-1.8 for chickens
• FCR values 8-10 for cattle
• Yield of high-quality protein from salmonids is
  55
• Total yield from poultry or cattle is lower and
  quality varies with cut

15
Brief history of fish nutrition

• Prior to 1950s
• empirical feed formulation research with a
  variety of ingredients
• Nutritional diseases quite prevalent
• Little solid information on nutritional
  requirements
• 1950s and 60s
• Golden age due to development of semi-purified
  diet that allowed single nutrients to be deleted
  and added back (Halvers PhD work)
• Vitamin and amino acid requirements of salmon and
  trout were discovered
• Common nutritional diseases eliminated

16
Brief history of fish nutrition

• 1970s
• Essential nutrient list expanded to other species
• Refinement of nutrient requirement estimates
  using new approaches to assess nutritional
  adequacy
• 1980s and 90s Aquaculture production takes off
• Need for economical and efficient grow-out feeds
• New species including those with larval stages
• Low-pollution feeds (low-phosphorus, highly
  digestible)
• 2000 until now
• Main story is alternative protein and lipid
  sources
• Sub-plot is supplements to enhance disease
  resistance, provide semi-essential nutrients
  and to produce healthful products (low in POPs,
  high in omega-3 fatty acids)

17
Dietary nutrient requirementsPioneering fish
nutrition research

• Development of semi-purified diet (1953) that
  supported normal growth
• Establishment of quantitative dietary
  requirements of vitamins amino acids (1960s)
• USFWS Western Fish Nutrition Laboratory
• John Halver colleagues
• Pacific salmon were focus, hatchery support
• all work was conducted with fry fingerlings

18

Vitamin requirements of salmon and growing
chickens (IU or mg/kg dry diet)

• Vitamin Salmon/trout Chickens
• Vitamin A 2500 1500Vitamin D 2400
  200Vitamin E 50 16Vitamin K
  unknown 0.5
• Thiamin 1 1.3
• Riboflavin 7 3.6
• Pyridoxine 6 3.0 Pantothenic acid 20
  10
• Niacin 10 11
• Biotin 0.15 0.10Folic acid 2 0.25
• Vitamin B12 0.01 0.003
• Ascorbic acid 50 not required
• Choline 800 500myo-Inositol 300 not
  required
• values in yellow are lower for chickens

19

Semi-purified diet for salmonids

• Ingredient Percent in diet
• Vitamin-free casein 40.0
• Gelatin 8.0
• Dextrin 10.0
• Wheat starch 10.0
• Carboxymethylcellulose 1.3
• Alpha-cellulose 6.0
• Mineral mixture 4.0
• Vitamin mixture 3.0
• Amino acid mixture 2.0
• Choline chloride (70 liquid) 0.3
• Herring oil 17.0

Proximate category Percent Moisture
28-30 Crude protein 34 Fat 17 Ash 5
20

Determining nutrient requirements in fish

• Feed semi-purified diet, adding back graded
  levels of single essential nutrient
• measure response variables
• growth, feed conversion ratio, survival (1950s)
• tissue nutrient levels, assuming that they
  plateau at requirement level (1950s through
  today)
• measure activity of enzymes that require
  essential nutrient as co-factor (same assumption,
  1980s)
• measure excretion of nutrient or metabolites
  (1990s)
• Nutrigenomics (study of effects of nutrients on
  gene expression and single gene products in
  tissues)

21
Qualitative dietaryarginine requirement(Halver)
22
Relationship between thiamin intake and liver
thiamin concentration
23

Nutrient requirements of salmonids

• Protein Ten essential amino acids
• Lipids Omega-3 fatty acids (1 of diet)
• Energy Supplied mainly from lipids and protein
• Vitamins 15 essential vitamins
• Minerals 10 minerals shown to be essential
• Carotenoid Needed for viable eggs
• pigments
• NOTE Other minerals are probably essential but
  can be obtained from rearing water

24
Criteria or method used to establish a dietary
vitamin requirement affects value

• Response variable
• absence of deficiency sign (minimum level)
• tissue saturation or plasma level
• enzyme activity
• Statistical evaluation
• broken-line (Almquist plot)
• curve-fitting and models
• fit curves but are they biologically relevant?
• do we chose 95 or 100 response as requirement?
• Real-world environmental conditions
• crowding, water quality, pathogen load etc.

25

Ascorbic acid requirements of salmonids

• Requirement Comments
• 15-20 ppm Prevents deficiency signs
• 250-500 ppm Supports maximum wound healing
  activity
• 1000-2500 ppm Supports maximum
  disease resistance in laboratory challenges
• gt2500 ppm Maximum tissue storage levels and
  max. immune response
• When included in purified diet, with ideal
  conditions and no oxidation of vitamin C

26

Mineral requirements of fish

• Macrominerals (g/kg diet) Microminerals (mg/kg
  diet) (trace elements)
• Calcium Iron
• Phosphorus Manganese
• Sodium Copper
• Potassium Zinc
• Chlorine Cobalt
• Magnesium Selenium
• Sulfur Iodine Molybdenum
• Required in the diet, but not always
  supplemented in practical feeds

27

Carotenoid pigments in farmed salmon and trout
feeds

• Synthesized products
• Carophyll red
• Carophyll pink
• Natural products
• Krill meal
• Phaffia yeast
• Marine algae
• Crustacean waste (crab, shrimp, crayfish)
• Note astaxanthin shown to be essential nutrient
  for salmon to produce viable offspring

28
Nutrient requirements Halvers contribution

• Complete estimates of nutrient requirements only
  done for juvenile Pacific salmon and rainbow
  trout
• Halvers work never duplicated for Atlantic
  salmon
• Dietary requirements still based on Pacific
  salmon work
• Atlantic salmon production
• gt1,200,000 metric tons
• 2,000,000 metric tons of salmon and trout feed
  per year
• The nutritional information upon which this
  industry is based is that of Halver and his
  colleagues

29
Changes in protein and fat levels in trout feeds
30
Changes in protein and fat levels in salmon feeds
31
Changes in feed conversion ratios for salmon and
trout
32
The authoritative text for all fish nutritionists