Flashcards in 6b Nutritional Peculiarities of Cats Deck (34):
What are the amounts of energy substrates for cats?
protein > fat > carbs
Do cats have a carb requirement?
Do cats have a fiber requirement?
yes, for GI health
How do the taste receptors differ in a cat?
- not attracted to carbs or sweeteners
How does pancreatic alpha-amylase activity differ in cats compared to dogs?
- only 5% of those in dogs
How does disaccharidase activity in cats compare to those in dogs?
- only 40% activity of those in dogs
Describe the expression of SGLT in cats.
- reduced expression along crypt-villus axis
- cats cannot increase expression of this transporter when sugar eaten
Describe hexokinase, glucokinase and fructokinase activity in cats. (convert glucose to glucose-6-phosphate)
- hexokinase activity in tissues normal
- glucokinase activity in liver minimal so cannot clear large amounts of glucose
- lack fructokinase (fructose excreted in urine)
Describe how cats blood glucose changes in a carb free diet.
- increases more than a carb diet
How do cats meet glucose requirements in a carb free diet?
- rely on gluconeogenesis to sustain blood glucose
- source of carbon skeleton: AA, propionate and glycerol
- some amino acids can enter the Krebs cycle
Why do cats have a high protein requirement for maintenance?
- not due to amino acid requirement
- due to high amino acid turnover (high activity of hepatic enzymes, urea cycle enzymes)
How high is the feline protein maintenance requirement compared to dogs?
- kitties 50% higher than puppies
- adult cat 2x higher than adult dog
How do cats control protein metabolism?
- they don't
- are constantly metabolizing fixed amount of protein
- can't decrease liver enzymes
- muscle wasting can occur quickly
How do cats control the urea cycle?
- cannot reduce enzymes in urea cycle so do not have nitrogen pool in the body
- highly efficient detoxification of nitrogen wastes
- contrast to omnivores
- non adaptive to dietary protein levels
What happens with regards to the urea cycle during fasting or reduced protein intake?
- urea cycle intermediates become depleted
- with protein meal, intermediates replenish
- key intermediate: ornithine
- dietary precursor: arginine
Why do cats have an arginine requirement?
- low activity of enzymes in small intestine to produce arginine from ornithine and citrulline
- pyrroline-5-carboxylate synthase
- ornithine aminotransferase
What happens with an arginine deficient meal is fed?
- ammonia cannot be converted to urea
- ammonia toxicity in less than an hour
- death within 2-5 hours
but this is rare
Why do cats have a taurine requirement?
- taurine is a beta-amino sulfonic AA
- important for bile acid conjugation
- essential for normal retinal, cardiac, neurologic, reproductive, immune and platelet function
- cat liver has limited capacity to synthesize taurine
- limited enzymes to convert methionine and cysteine to taurine
Why do cats need taurine for bile acid conjugation?
- cannot change to glycine conjugation
- enterohepatic circulation usually occurs
- but microbial degradation = beconjugation
- obligate taurine loss
Where can a cat get taurine?
- abundant in animal tissues, absent in plant
What effects does taurine deficiency have?
- feline central retinal degeneration
- reproductive failure and impaired fetal development
- feline dilated cardiomyopathy
- hearing loss and impaired immune function also reported
What is the first limiting AA in cat diets formulated with natural ingredients?
Cysteine can provide how much of sulfur AAs?
- but low in vegetable based diets and must be supplemented
Why do cats have a higher methionine/cysteine requirement than other species?
- cysteine synthesis
- limited taurine synthesis
- high rate of methionine catabolism
- hair synthesis
What effects does a tyrosine deficient diet have?
- redder hair coat
- needed for melanin synthesis
What is the main form of stored energy in cats?
- major fat depots
Why do cats have an arachidonic acid requirement?
- high ability to digest and use fat
- cannot synthesizer arachidonic acid from linoleic acid
- low hepatic delta6 desaturase
- only in fats from animal tissues
Why do cats require niacin?
- high activity of picolinic carboxylase
- cannot convert tryptophan to niacin because of competing path
What happens with niacin deficiency?
- Pellegra (4 Ds)
- diarrhea, dermatitis, dementia and death
Describe pyridoxine requirement in cats.
- vitamin B6
- 4x higher than dogs
- high pyridoxine turnover
Describe vitamin A requirement in cats.
- needed for growth, development, immune system, vision
- cats cannot convert b-carotene to vitamin A
- required preformed vitamin A (animal tissue)
Describe vitamin D requirement in cats.
- needed for calcium absorption, muscle contraction, blood clotting, nerve conductance, phosphorous homeostasis
- have insufficient 7-dehydrocholesterol in their skin so cannot meet metabolic need for vitamin D photosynthesis
Describe water requirement in cats.
- ancestral adaptation to desert environment
- survive on less water than dogs
- compensate low water intake by highly concentrated urine
- risk of crystalluria or urolithiasis
- Feline lower urinary tract disease complex (FLUTD)