Nutrition of the Special Senses Practical

what is palatability

dietary characteristics stimulating a selective response due to the:

sensory characteristics of the food

nutritional effects

physiological effects

name 5 other factors affecting food selection

availability

physiological condition

safety

light

bowl cleanliness

noise

location

time of day

how do animals learn about foods

affective conditioning

cognitive conditioning

what is affective conditioning

first time the food is seen - forming opinions based on:

senses when eating

post-ingestive effects - physiological and nutritive

so just assessing palatability really and either accepting or rejecting but decision-making is slower as less knowledge

cognitive conditioning

food already seen - sensory properties are now linked to physiological and nutritive consequences so decision of whether to eat is easier so decision-making is faster

what is conditioning then

learning to associate two factors that aren’t inherently linked - sensory and effects

why are animals overfed but undernourished

they have a separate protein appetite to ensure target protein intake so eating excessive carbohydrates doesn’t make you full and leads to overconsumption and predisposes animals to insulin resistance → metabolic disease vicious cycle

sight - how are young animals influenced

they are influenced by what they see their mother eating

• give mother mother and baby food for cats so they can copy - give mothers a wider range too so kittens are less fussy when older - diet habits are established by 6-8 weeks old and adapt within 5 hours not 5 days like when adult

• choose point of weaning in lambs

how do sheep associate coloured objects like buckets with food

zona inercta and lateral hypothalamus - assocciation

why can sheep distinguish between different hues

everything they eat is green - colour of ryegrass is proportional to stage of maturity and therefore protein content

2 functions of smell in terms of food

locate food source

assess food for toxicity

stimulate gut secretions

which species relies most heavily on scent

dogs - more olfactory receptors and larger olfactory bulb

larger nose so increased airflow - consider brachycephalics

why don’t farm animals smell food

they are surrounded by it - herbivores so don’t need to hunt but use touch to avoid sharp objects

• detect sodium bicarbonate when deficient - cow

reasons to stop eating due to change in smell

respiratory disease - less smell

smell of washing up liquid

new feed

what is the difference in function between smell and taste for food

smell - find food

taste - ensure it is safe and appropriate

how is food related to GIT

the food preference of an animal is the same as the food that it is adapted to digest

5 tastes

sweet - carbohydrates

umami - amino acids

bitter - toxins (anti-nutritive factor)

salty - Na+ and Cl- ions

sour - H+ ions

Fro m that list, what is a nutritive factor

sweet, salty, sour, umami

which other nutritive factors are there

fat, calcium, water

are animals predisposed to know which foods are toxic?

yes from their taste, but can be conditioned to change this so something might taste nice but it made them ill so they won’t eat it

hunger can overcome repulsion

what is the primary sense in birds

vision

what substances do manufactueres add to livestock feed to change the taste and which animals

calves and piglets creep feed

MSG

how are chickens adapted to find calcium in diet

sensitive to calcium so eat a high calcium diet if deficient, and a low if have enough

high taste bud concentration in the oral cavity allowing for this

why should you advise grit for a chicken

a high calcium diet means the chicken won’t eat as much if it is fine with calcium, or won’t eat enough calciium due to being full if deficient, so grit can be used as it won’t fill them up but is pure CaCO3 so they can advise themselves

which nutritive factor are cats sensitive to

amino acids - obligate carnivores

why are cats less sensitive to sodium

protein has a high sodium content

common issues with feeding management in cats

broken kibble - worse mouth feel and no crunching bone effect

tinned and minced - supralingual prehension with dorsal part of the tongue so not raising its head due to continuously swallowing - owner thinks it is particularly palatable so feeds more

jelly - large pieces to swallow so lifts head and owner thinks they are looking at them in an unimpressed way

so intepretation and feeding management

what temperature should cat food be served at?

blood temperature - not chilled

neophilic cats

if both feeds are abundant and familiar then this cat will choose the less abundant to maximise long term nutritional benefits but preferences are short-lived and affect quantity eaten so BCS

mesophilic cats

like medium stuff - alternate known but not too many changes or neophobia

where should the water and food bowls be placed for a cat

water - away from food - perceived as contaminated with raw meat

food - away from litter tray - unhygienic

client factors that are changed by the manufacturer to make the feed more appealing to the client

shape, size, colour, marketing

animal factors

palatability and environmental factors