Hindgut Fermenters Flashcards
Which linkages in soluble carbs?
Alpha
Which linkages in insoluble carbs?
Beta
List the macronutrients
Carbohydrates, Proteins, Lipids
Unit of measuring macronutrients?
g/kg
What are micronutrients?
Vitamins and minerals
Unit of measuring micronutrients
mg/kg
How are proteins, lipids and alpha linked soluble carbs digested?
Enzymatic (secreted by animal)
How are insoluble beta linked carbs digested?
Microbial fermentation
Describe diet of herbivores
High in CHO, low protein, low E
Consume lots to satisfy nutrient and E requirements
Spend lots of time eating
What 2 things does hindgut fermenter GIT need to enable?
Enzymatic digestion of soluble compounds
Microbial fermentation of insoluble compounds
Is enzymatic a quick or slow process?
Quick (0.5 hrs in equids)
Where does enzymatic digestion take place?
Stomach and/or si
Is microbial fermentation a quick or slow process?
Slow (1-2 days in equines)
Where does microbial fermentation take place in ruminants and hindgut fermenters? (What are the fermentation chambers?)
Ruminant: foregut (rumen)
Hindgut fermenters: hindgut (caecum and colon)
Describe generally the GIT components of hindgut fermenters
Have unremarkable si and large caecums and/or colons
List 4 cæcal fermenters
Guinea pig
Hamster
Rabbit
Koala
List 4 colon fermenters
Orangutans
Equids
Rhinoceros
Elephants
Aside from herbivores, which other feeders utilise hindgut fermentation and provide 2 examples
Hint: also benefit from a diet higher in protein and soluble CHO but still have fairly well developed caecum, and/or colon
Omnivores
Rats have well developed caecum
Pigs have well developed caecums and colons
Do rabbit and Guinea pig teeth continually grow or erupt?
Grow
Do horse teeth continually grow or erupt, what do you call this?
Erupt, hypsodont teeth
Which teeth continually grow in rats?
Incisors
What is the morphology and purpose of the incisors in hindgut fermenting herbivores?
Sharp and overlapping for cutting leaves and twigs
What is the purpose of having flat molars creating an occlusal surface?
To grind fibrous ingests into smaller particles
In terms of dentition, why must fibrous feed be provided?
To wear down teeth
What are the caecum and/or colon called in hindgut fermenters?
Fermentation chambers
What is the role of saliva from salivary glands?
Lubricate food when swallowed and buffer acid in stomach
Which additional salivary gland (to parotid, mandibular and sublingual) do rabbits have?
Zygomatic
Describe saliva prod in rabbits
Continually from mandibular gland and in response to food intake by others
Describe saliva prod in horses
In response to chewing only
What three components are always present in saliva?
Water and mucus for lubrication and bicarbonate to buffer acidic contents of stomach
What else is present in rabbit and and rat saliva but not in horses?
Alpha amylase (starch digestion) but action is low
Describe the stomach of hindgut fermenters
Small and simple
Describe their feeding strategy
Trickle
How fast does ingests pass thru the stomach?
Fairly rapidly (usually 15mins to 2hrs but slightly slower in rabbits)
Through what structure does food enter the stomach?
Cardiac sphincter (prevents regurgitation in horse, rat, gp, rats)
Describe cardiac region of stomach
Non glandular, pH 6-7, no secretions = no protective mucus lining
Describe funding and pyloric regions of stomach
Main secretory part
Parietal cells secrete HCl
Chief cells secrete pepsin
Mucus secreted to protect against acid
pH 1-2
Describe pyloric region of stomach
Gastric secretion stimulates HCl production
Which species needs continuous HCl secretion in stomach to help prevent ulcers?
Equines
Where does ingesta exit stomach
Pyloric sphincter
Which type of bonds are targeted by enzymatic secretions in the stomach and si?
Alpha bonds
How long does it take for ingesta to pass through si of hindgut fermenters?
1-3hrs
Describe how ingesta passed from si to colon in equids
Ileum to caecum via iléocaecal valve then leave caecum via caecoventral colonic valve
Describe how ingesta passed from si to colon in rabbits
Three way connection btwn ileum, caecum and colon, called the iléocaecocolic junction
What is the function of the ileocaecocolic junction structure in rabbits?
Facilitâtes selective retention of fluid and small particles and expulsion of fibrous material
Remember rabbits are cæcal fermenters whilst horses ferment in caecum and colon
Which food materials remain upon entry to the large fermentation chambers?
Insoluble fibrous materials: hemicellulose, cellulose, lignin (completely indigestible)
Why do fermentation chambers need to be able to store ingesta?
The process of microbial fermentation in the caecum and colon takes time
Describe the function of the caecum and colon in hindgut fermenters
Provide space for mixing ingesta with microbial populations and a large surface area for abs of nutrients, fermentation prods and water
How is the hindgut structured to increase surface area?
It is sacculated
Remember: some species also have flexures involved in selective retention
Does mucosa lining of hindgut contain crypts and/or villi?
Crypts but no villi
What and why do goblet cells produce?
Mucus to protect against acids produced in fermentation
What is pH optimum of microbes and how is this maintained?
6-7 so secrete bicarbonate and phosphate into li to neutralise acidic products of fermentation (SFAs)
Where does microbial fermentation take place in equids?
Caecum and colon
Remember: some books call them colon fermenters as colon is enlarged
Which food materials are selectively retained in the equine caecum and colon?
Course particles hi in fibre
Where does abs of fermentation products take place in equids?
Caecum and colon
What happens to ingesta of equids in the small colon (btwn large colon and rectum)?
Final site of water abs
Formation of faecal balls
Where does microbial fermentation mostly occur in rabbits?
Caecum
What is selectively retained in the caecum of rabbits for microbial fermentation?
Fine particles (and fluids also retained)
What are the two fates of the products of microbial fermentation in rabbits?
Absorbed in the caecum or expelled as caecotrophs
What happens to fibrous material in the large fermentation chambers of rabbits?
Fibrous material (insoluble CHO >0.5mm) are selectively progressed thru colon for expulsion
This is important to promote GIT motility
Explain caecotrophs in rabbits
Soft faeces
Excreted during rest periods so rabbits have constant nutrition throughout day
Rich in aas, VFAs, enz, Vits B and K, microorganisms
Coated in mucus to protect against acid in stomach (not digested here)
Pass into si where contents digested and absorbed
When do rabbits excrete hard faeces and what do they consist of?
During feeding phase (dawn and dusk)
Consist of indigestible fibre
What the microbes groups can be found in the hindgut of fermenters?
Bac, fungi, Protozoa
Describe the symbiotic relationship btwn the animal and the microbes
Animal provides enviro where microbes can survive and grow in ezxchange for them breaking down insoluble parts of plants the animals have eaten
Why do dietary changes need to be made v. slowly?
So microbes can adapt
Disruption of fermentation process can cause colic in equids
Describe stage 1 of microbial fermentation
Microbes attach to cell wall compounds
Stage 2 microbial fermentation
Microbes excrete enz to break down beta links btwn individual molecules of cellulose and hemicellulose
Stage 3 microbial fermentation?
Individual molecules then processed by bac to produce VFAs and gases
Stage 4 microbial fermentation?
VFAs abs thru gut wall into blood for use as E source
List and explain benefits of products of microbial fermentation
VFAs (butyrate, propionate, acetate) for E
Heat
Vits B and K
aa (in rabbits and species who perform coprophagy)
Gases (issues if trapped; bloat, colic)
What conditions do the microbes require?
Stable temp, pH 6-7, regular food supply, no O2
What enz do go lack that is involved in prod of ascorbic acid?
L-gulonolactone oxidase
What are the three purposes of insoluble CHO/fibrous materials in hindgut fermenters diets?
Ensures microbial pops have adequate food supply
Promotes GIT motility
Provides E and vits
Consequences of too little fibre?
Reduced wearing of teeth
Reduced motility
Reduced microbial activity/growth
Reduced E
Consequences of too hi fibre?
Impacted GIT, reduced cæcal activity (rabbit)
List the functions of dietary fats/lipids
Celle membranes, hormone prod, fat-soluble vit abs, storage of E
Is E a nutrient
NO: gained from utilisation of nutrients; CHO, fats and proteins
How much of BW should equids consume as DM per day?
2-2.5%
Minimum 1.5% as forage
If increase exercise demand of equids, what dietary changes are needed?
Replace some fibre-based feed with concentrate feed (more E dense)
What are concentrate feeds fortified with?
Vits and mins
When might vitamin and mineral supplements be useful to add into equid diet?
If feeding only forage, as do not add extra E or protein
*sometimes called a balancer
How much of their BW should rabbits consume daily as DM?
2.4-2.7%
Why is it an issue that rabbits consume sweet food in preference
Obesity
What kind of plants do rabbits select?
Young (soft and nutrient dense)
Their diet is usually higher in CP and soluble CHO than other herbivores
How does quantity of protein in rabbit diet affect caecotroph prod?
Hi protein = less caecotrophs
Low protein = more
How does fibre in diet affect caecotroph prod?
Excessively hi or low = less caecotrophs due to increased cæcal retention
How much do caecotrophs contribute to daily nutrient intake?
Marginally
What are the main E sources of rabbits?
Sugars abs in si and VFAs from cæcal fermentation
Rabbits x digest starch as well as other mono gastric so need to avoid overloading the system
Why is grass good for rabbits?
Abrasive to teeth, hi fibre, good protein levels and good source of vits
If not grazing which hay is epbest for rabbits due to its hi fibre and lower protein content?
Meadow hay
Alfalfa and pellets are hi E and protein and can lead to obesity
Why feed pellets over mixes?
Avoid selective feeding
What should fibre content of commercial rabbit food be?
> 18%
What is optimum rabbit pellet size?
6.3mm long and 4.7mm diameter
Give examples of succulents that may be added to rabbit diets
Cauliflower, carrots, broccoli, lettuce, celery leaves, chard, green peppers, dandelion leaves, kale, cabbage
Why do gp need approx 4% BW in DM every day when rabbits only 2-2.5%?
Have less efficient digestion
What aspect of feeding are gps v. vulnerable to?
Dietary changes
Why are gps more efficient at digesting fibre than rabbits are?
Rabbits selectively expel fibre
How should commercial gps mixes be stored to prevent deterioration of vit C lvls that feed is fortified with?
Dark, cool area
Vit C an also be given in water but need to ensure that gp actually drinks it
When do rats (omnivores) feed?
Dawn and dusk
What digestible feeds should rats diets be based on?
Fruit and veg and soft plant material
Plus occasional small a,lungs of grains, legumes, eggs, lean meat, insects etc
How should commercial rat mixes differ from other rodents feeds?
Lower fibre, higher fat and medium protein
Describe forage and concentrate feeds
Forage: grass, hay, haulage, straw
Concentrate: cereal grain based fed as mixes or pellets
Why might succulents be added to hindgut fermenting rodents diets?
Enrichment
Advantages of grass as forage?
Cheap, natural, appetising
Disadvantages of grass?
Nutrient value varies on species, maturity and selective grazing behaviour
Equids are susceptible to sugar content (risk of laminitis)
Be aware of weeds/poisonous plants in grazing areas
What can hay be made from?
Grass or legume (alfalfa)
How do grass and alfalfa hays compare?
Grass lower in protein, E and Ça but higher in alfalfa
What has significant affect on nutrient lvl and hygienic quality of hay?
Processing and storage
Slow drying or baled when damp = microbial growth
Slow drying and rain = leaches nutrient
Warm and damp storage = microbial growth
Why is meadow grass hay recommended for Guinea pigs and rabbits?
Lower in nutrient value than seed hay (grown from seed for purpose)
Which type of hay ,ost commonly fed to equines?
Grass hays (seed or meadow)
Alfalfa to hi performance horses as higher E
Describe how haylage (fed to equines is made)
Grass cut earlier than for hay
Wilted in field for 48hrs then wrapped to prod anaerobic enviro where lactic acid bac ferment sugars and reduce sugar content of forage (less so than silage tho)
Why need more freshweight of haylage than hay?
DM content is lower (batch test as DM and nutrient content variable)
Why is haylage good for horses with respiratory issues?
Less dusty than hay
Why haylage x recommend for rabbits and gps?
Too nutritious
Describe use of straw in equid diets
Small quantities can be added to add fibre
Low digestible it’s so careful of impactions
Often used in chopped forages (chaff) with hay
Not recommended for rabbits or gps due to impactions
Which horses are short chopped chaff forages recommended to?
Those with dental issues
Why should rabbits and gps be fed long forages?
Encourage chewing and prevent excessive intake
Why are commercially available concentrates better than feeding individual cereal grains?
Balanced and fortified to meet nutritional requirements
Known composition
More practical for purchase and storage
Why can both mixes and pellets be fed to horses?
No reports of selective feeding so no risk of nutritional imbalance
How might breeding rabbit concentrate formulations differ?
Higher CL lvls
How often can fruits be fed to rabbits and Guinea pigs?
Once a week in small amounts e.g. apples, pears, melons, bananas, kiwis
Why cut equine succulents e.g. swedes, parsnips lengthways
To prevent lodging in œsophagus
