animal nutrition Flashcards
what are required nutrients, why are they required and how does availability vary
- carbohydrates, lipids, proteins, vitamins, minerals and water
- provide: the fuels, building blocks, and the solvent of our system (water)
- availability: varies / depends on whether or not they can be stored or synthesised
describe the process of feeding to elimination
ingestion: act of eating or feeding, surveys / classifies
digestion: food is broken down into molecules small enough to absorb
- mechanical: chewing, increases surface area for chemical processes
- chemical: broken down to monomers / simple structures via enzymes
absorption: take up small molecules such as AA and simple sugars
elimination / excretion: undigested material passes out of the digestive system
what are suspension / filter feeders
- aquatic animals
- capture fine particulates suspended in water
- move water through a filtering structure to aggregate (cilia) and consume food
- allows water circulation
what are bulk feeders
- mechanical digestion
- eat relatively large pieces of food, no chewing
- snakes: able to consume an entire organism (bird, rat, kangaroo)
what are generalist feeders
- chewing, breaking down of substances into smaller particles
- eats a little bit of a range of substances (wide diet)
- not ‘picky’ eaters, able to consume variety of food
- herbivores and carnivores
what are specialist feeders
- consumes a lot of a narrow range of food types (specific)
- eat body weight in leaves / flowers / seeds per day
- absorb all soluble sugars
- consume a lot of food (require lots of energy)
- koala, red panda, pandas: don’t digest cellulose, lots of food, robust stomach
- pig-me possum: eats nectar / pollen, comb / tongue, high sugar content, allows pollen tube to germinate and digest content of pollen
- honey eater: tongue / straw, drink pollen, specialised beak to reach nectaries
what are fluid feeders
- suck nutrient rich fluid from a living host
- mosquitos (blood), ticks (blood), hummingbird / bees (movement of nectar), aphids (central vein, phloem sap of plants)
what are substrate feeders
- animals that live in or on their food
- eat through soft epidermis of leaves, leaves a dark trail of faeces in its wake
- worms, larvae, maggots (burrow in animal carcasses)
what are deposit feeders
- aquatic animal that feeds on small specks of organic matter that have drifted down through the water and settled on the bottom
- examples: eels, crabs, snails
what is intracellular digestion (choanocyte / sponge)
- food vacuoles: cellular organelles, hydrolytic enzymes breakdown food, fuse with lysosomes
- phagocytosis / pinocytosis: food or liquid
- sponge: mesophyll, epidermis, pores, spongocoel, choanocytes, amoebocytes (transport nutrients to other cells)
- choanocyte: flagellated, movement of flagella draws water through collar, food particles trapped, engulfed and digested / transferred to amoebocytes
- independent survival
what is extracellular digestion
- breakdown of food in compartments that are continuous with the outside of the animals body
- able to digest larger pieces of food than in phagocytosis
- two way digestive tract: simple system, absorbed across body wall into the cells, waste exits the same way that it enters (gastrovascular cavity)
- cannot ingest food while earlier meals are being digested
- hydra: gastro-dermis / epidermis
what is a one way digestive tract
- alimentary canal, regional organisation, complex foods
- movement of food in a single direction
- carry out digestion and nutrient absorption in a stepwise fashion
- ingest food while earlier meals are being digested
- regional specialisation, unidirectional movement
- specialised characteristics: reflect food type, dentition, fore gut verse hind gut or simple stomach
describe physical and enzymatic digestion, and how are they controlled
- P: mechanical change in size, increased SA for enzymes to break down, teeth, easier to swallow
- E: molecular level breakdown, association in mouth (salivary glands, lubrication, salivary amylase), stomach etc
- hormonal / neural control: coordinates process
what is an oral cavity
- chewing, secretion of saliva, salivary amylase (breaks down polysaccharides)
- physical digestion: mechanical break down, digestion relying on chemical degradation (acids) and enzymatic digestion
- salivary glands: secrete saliva upon presence of food in mouth (before entry,learned associations)
- salivary amylase breaks down proteins into smaller polysaccharides
what is a stomach
- stores food, begins digestion of proteins
- gastric juice: digestive fluid, acidic, churning action (chyme), HCl and pepsin
- HCl: disrupts matrix that binds cells together, low pH (2) denatures proteins (unfold), increases exposure of peptide bonds
- pepsin: works best in highly acidic environments, breaks peptide bonds
- components of gastric juice are kept inactive until released into lumen (acidity doesn’t destroy cells)
- parietal cells: secrete H and Cl combine in lumen
- pepsinogen: inactive pepsin, HCl concerts pepsinogen to active pepsin
what is a pancreas
- aids chemical digestion
- produces an alkaline solution rich in bicarbonate and enzymes
- bicarbonate (HCO3-): neutralise acidity of chyme, act as a buffer, focus on absorbing material
- trypsin (enzyme): further breaks down dipeptides / peptides into AA
- lipidase: digestion of fats, breaks fats / lipids into fatty acids and glycerol molecules
what is a liver
- detoxifies, secretion of bile
- important in digestion, breaks down / emulsifies lipids and fats
- bile: contains salts, act as emulsifiers (detergents) that aid in digestion / absorption of lipids
- stored in the gall bladder
what is a small intestine
- beginning of most enzymatic hydrolysis of macromolecules (not fat or protein)
duodenum: chyme + liver / gallbladder / pancreatic digestive juices, digestion - carbohydrates: small polysaccharide + pancreatic amylase = monosaccharides
- proteins: small polypeptides + trypsin = AA
- lipids: fats + lipase + bile salt = fatty acid and glycerol
- jejunum and ileum: absorption of digestates (nutrients and water)
how does absorption of digestates occur
- cross lining of alimentary canal, diffuse into epithelial cells, reformed into proteins, carbohydrates and lipids
- bile: aids goblet formation / emulsification of fats, increased SA for lipase
- emulsification: dispersing one liquid uniformly through another
what is a large intestine
- caecum: fermenting ingested material (animals that ingest increased plant material)
- colon, rectum: recover / absorb water (osmosis), solvent of digestive juices, storage (12-24 hours to travel length of colon)
how does digestion of plant material occur
- cellulose and cellulase
- fore / hind guts: large chambers (front / rear of digestive system) where cellulose can be fermented by cellulase-containing microbes
- animals: don’t have the enzymes to do this work, rely on energy rich byproducts of microbes who can digest cellulose
- foregut fermenters: cattle, sheep and kangaroos
- hindgut fermenters: rabbits, possums and koalas
describe stomach and intestinal adaptations
large expandable stomachs
- coyote
- carnivorous vertebrates, long times between meals
- must eat as much as they can when they catch prey
length of digestive system
- koala
- herbivores / omnivores
- vegetation is more difficult to digest than meat due to cell walls (cellulose)
- furnishes more time for digestion and more SA for absorption of nutrients
- enhances processing of protein-poor eucalyptus leaves
what are the types of fermentation
hind gut (koala):
- food ferments in caecum / colon (large caecum)
- caecotrophy / coprophagy: seen in small mammals that use hindgut fermentation, energy rich molecules are lost with faeces, often eat their poo
foregut fermentation (sheep / cow):
- food held / fermented in anterior of stomach (large)
describe process of fermentation in cow
- rumen: chewing and swallowing of grass
- reticulum: start digesting, cow periodically regurgitates and re chews cud
- omasum: re-swallows the cud, as it is now increased accessibility for microbial action
- abomasum: true stomach, contains enzymes
describe foregut fermentation in birds
- oesophagus
- crop (temporary food storage)
- stomach (acid secretion)
- gizzard (no teeth, grinding sac, muscular, abrasive, mechanical digestion)
- not relied upon by all: modification of crop, replace large flight muscles, clumsy, can eat vegetation (rarity), hard to fly if they have a stomach of fermenting muck
