Lecture 17- Australian Native Animal Nutrition Flashcards
1
Q
What is the case with crocodiles?
A
- In-discriminant and opportunistic feeders
- Increases in body size increases prey size (insects to vertebrates like cattle)
- Digestive energy costs are high
- Stomach capacity 3-15% bodymass
- Lower than reptiles like pythons
- There has been research into commercial crocodile diets • Pellets etc.
- American alligators have been successfully fed a veg based pellet
- Most active at night
- Will eat anytime prey is present
2
Q
What do crocodiles eat?
A
- Little is known about the nutrient requirements
- Farmed animals do respond to differences in nutrient intake
- Do not need to feed daily
- But increased number of feedings improves efficienc
3
Q
What are the characteristics of kangaroos?
A
- Macropods
- Dental structure varies between species • 32-34teeth
- Molar teeth are replaced as the animal ages (up to 5 sets) • Large single pair of lower incisors
- Some macropod species eat invertebrates, fruits & seeds (musky rat kangaroo) • Browsers (quokkas, swamp wallabies) eat shrubs & soft plants
- Grazers feed predominately on grass
4
Q
What is kangaroo digestive tract like?
A
- Swamp Wallabies (& others) have an unusual oesophagus lined with numerous papillae
- Foregut fermentation
- Anatomy very different to ruminants
- Oesophagus opens into funnel shaped region
- Extends along inner curvature of the stomach
- Separates coarse from fine plant materials
- Fine material → hindstomach
- Secretes HCl & proteolytic enzymes
- Coarsematerial→forestomach
- Bacterial fermentation, largest section
- Similar VFA production to sheep
- Divided into sacciform & tubiform forestomachs
- Glandular & secretes mucus
- Smallcaecum&colon
- Water absorbed in distal colon
5
Q
What are more details about kangaroo nutrition?
A
• Monovular
• Polyoestrus (22-46 day cycle)
• Ovulation occurs a few days before or after parturition
• If conception occurs the zygote will develop to blastocyst then enter diapause for as long as
lactation occurs
• Thus conception does not interrupt the oestrus cycle, lactation does.
• Does not happen in western grey, musky rat or the tree kangaroos
• Unique lactation
• Sustains neonate from embryonic form to after birth (can be over 1 year)
• Milk composition markedly changes throughout lactation
6
Q
What are the characteristics of koalas?
A
- Has few natural predators
- No specific requirement for shelter
- Little to no resource competition
- Thus food is the major determinant of habitat quality
- Very low basal metabolic rate
7
Q
What is the koala diet?
A
- Specialised folivore of Eucalyptus
- Folivore = herbivore that specialises in eating leaves
- Will eat from many (>120) different trees within their range • Eat from both Eucalyptus and non-eucalypts
- Prefer certain eucalypt species over others • Not as fussy as believed
- Do eat from many species and are rather generalist
- Select feed based on morphology and chemistry • Andpalatability
8
Q
What is koala’s digestive tract like?
A
- Long retention time for food
- Maximises nutrient extraction and absorption
- MRT > 100 hrs!
- Influenced by age and status
- Long caecum (200 – 2000 cm)
- Largest in relation to body size of all mammals • Hind-gut fermentation
- Teeth designed to tear and shear leaves • Teeth wear with age
9
Q
How much do koalas eat?
A
- How much do Koala’s eat?
- Like all species this is dependant upon the nutrient content of the feed
- Dietary preferences influence intake • Species offered etc.
- Estimated intake ranges from 14 – 57 g kg-0.75 per day • About 500g per day
- Other factors influence intake
- Tree size: larger trees preferred (to sit in) but may not necessarily have high quality feed
- Seasonal variation: leaf age (young is preferred), toxic compounds, leaf water content etc.
- Regional variation: location changes tree type and preferences. Captive Koalas also will have little ‘choice’
10
Q
How does nitrogen figure in koala nutrition?
A
- Koala’s select for low fibre
- Nitrogen levels vary but generally Koala’s will select for higher nitrogen contents
- 1.1% total nitrogen preferred (but
11
Q
What is a platypus?
A
- Freshwater egg laying mammal
- Semi-aquatic
- Relatively unchanged since the time of dinosaurs
- Consume insects, molluscs, worms, eggs (larvae), small frogs etc. • Dive for
12
Q
What is platypus physiology?
A
- Cloaca
- Common hole for urine and fecal excretions and reproductive organs
- Poor vision
- Venom gland in thigh and spur
- Only used once sexual maturity is reached • Spur used to determine sex and age
- Toxic to smaller mammals (not humans)
- Simple digestive tract
- Bill used for sensing food
- Adults do not have teeth (small teeth in early life but these are lost) • Adults have keratinous grinding pads (grind food thoroughly)
- Small stomach and short gut transit time (~5 hrs)
13
Q
What is an echidna?
A
- Egg laying monotreme
- Thick skin with fat layer
- No nipples
- Milk expressed into pouch skin via hair follicles
- Beak has receptors to sense food • Produce lots of saliva
- For food but also nasal secretions due to sniffing
- Small eyes but good vision
- Better colour vision than humans?
14
Q
What is the echidna digestive system like?
A
- No teeth
- Food secured by the tongue & sticky saliva
- Termites, ants etc.
- Tongue can be extended 18cm beyond the snout
- Can protrude and retract >100 times per min
- Prey items crushed between tongue and hard palate • Simple monogastric digestive system
- Stomach is non-glandular and does not digest protein • High pH of ~6.2
- Lined with stratified epithelium to grind food
- Slow passage rate of food (~2 days)
15
Q
What is echidna nutrition like?
A
- Prefer termites to ants
- Diet is high protein and high fat
- Get most of their water from food • Termites can be 80% water
- Often fed meat etc. in captivity • Obesity can occur
