23: Fish and Reptiles Flashcards
How many different species of fish are kept in aquariums? Where do we get the info about how to feed them?
> 5,000
Extrapolate data from aquaculture (no detailed info about their nutrient requirements)
Diets of aquarium fish
Few carnivorous
Many omnivorous
Many herbivorous
Major classifications of aquarium fish
- Temperature (warm (tropical) or cold (temperate) water)
- feeding behaviour (top, bottom or middle feeders // night or day feeding)
- social behaviour (single or mixed pops in one aquarium)
One word to describe digestive physiology of fish. What are the consequences of this?
Simple
Material passes through quickly and digestion is lower
Teeth in fish? Stomach? How is food fed/eaten?
Few fish species have teeth
Stomach generally small (larger in omnivores or herbivores)
Small fish have no stomach (food passes directly into intestine)
Food eaten as whole or bite-sized particles
Major factor affecting energy requirement of fish? Describe their energy requirement
Fish are ectothermic (body temp changes w environmental temp)
- ‘cold blooded’
- survival benefit bc require less energy to maintain life
- energy needs correlated to water temp
What happens to the energy requirement of fish in cold temperatures?
Fish slow down their metabolism and have a lower energy requirement (opposite of cats and dogs)
Protein requirement in fish
- rely more on aa than CHOs
- higher protein turnover than mammals (higher protein requirement too; 30 to 40%)
Starch utilization in fish? What type of processing is used when making fish food?
Omnivorous and carnivorous fish can utilize starch as long as it is properly processed
- utilization better in gelatinized form
Extrusion and flaking technology
Calcium and phosphorous requirements in fish?
Do not need as much as mammals
- no hard bones (means bones are not a source/reservoir for Ca in periods of deficit)
- need regular Ca supply
- uptake and excretion regulated through gills
Iron requirement in fish? Other minerals?
Iron >200 ppm interferes with oxygen transfer
Minerals (Na, K, Cl) for ionic control
- continuously adjusted in fish body
Requirement for water soluble vitamins in fish
Quickly dissolved in water (lost when pellet is fed in water)
- over-supplement fish feed with water soluble vitamins
Vitamin C is essential (fish cannot synthesize)
- deficiency leads to lordosis (upward and downward curvature of spine)
How does fish pigmentation work?
Most colours from carotenoids (>600 molecules known) from flower seeds, petals or algae
- spectrum of blues and greens to yellows, oranges and reds
- two major components: astaxanthin (red) and canthaxanthin (red-orange)
Requirement of omega-3 and -6 PUFAs in fish? Sources? How does this change with water temp?
Linoleic acid keeps fish membranes fluid
At 5-10C ratio of -3 to -6 should be 2 (more omega 3)
At 15-20C, ratio of -3 to -6 should be 0.5 (less omega 3)
Sources: fish, animals and plants
Why omega-3 f.a. instead of saturated in fish?
At lower temps omega-3’s are still liquid, while saturated fats can solidify and clog digestive system
What are dietary recommendations for reptiles based on? Types of diets?
Based on knowledge of natural diets and feeding history, clinical experience and comparative nutrition (nutritional research is limited)
Herbivorous, omnivorous, carnivorous
Digestive system of reptiles
Monogastrics
Simple, short GI tract, not much of a LI
Larger volume and length of cecum
Unique structure in iguana GI tract?
Baffles: projections of tissue into cecum and colon of iguana that slows flow of digesta to get more nutrients out of diet
How does the digestive system of herbivorous reptiles differ from mammals?
Numerous folds and partitions
- to slow passage through tract
- increases time for bacteria and protozoa to ferment food
Why are herbivorous reptiles larger than carnivorous?
- larger body size and digestive tract size will allow more vegetation to be consumed
- habitat and optimal temp range also influences size
How should water be provided to reptiles?
- must fit environment of animal
- proper depth of bowls or lids
- smell and taste of water
- proper interval
- proper humidity
Dehydration in reptiles causes… Too high humidity?
Dehydration causes gout (crystallisation of purines in joints) or excess drying of skin and inability to shed
High humidity causes hyperkeratinization (excess growth and scaling of skin)
Too low vs too high temp affect on energy requirement in reptiles
Ectothermic
- too low = decrease in food intake, nutrient requirements and growth
- too high = excessive metabolism of nutrients, decreased food intake and growth
Energy requirement of reptiles compared to mammals? Relation between metabolic rate and body size?
Reptiles require only 1/4 of energy of similar sized mammals
Inverse relation btw metabolic rate and body size (smaller the animal, greater MR per unit BW)
Protein requirement in reptiles
Carnivorous = 30 to 60% CP
Herbivorous = less than carnivores, 28% in green iguana for growth
High requirements so use animal proteins or high-protein seeds and nuts
Feeding of carnivorous reptiles
- invertebrate prey (worms, larvae) too low in Ca
- feeding only meat leads to excess protein and E and deficiencies in Ca and other minerals
- variety of prey should be fed
- cat food may be an option
