Posted on 07/25/2005 11:22:58 AM PDT by LibWhacker
As cat owners know, their feline friend would much rather chase and eat a live mouse than snack on the chocolate equivalent, and now researchers have discovered the reason – cats are simply unable to taste sweet things.
An examination of feline genetics has shown a significant defect in one of the genes that codes for part of the sweet taste receptor. This “huge deletion” of 247 base pairs in the gene that codes for the T1R2 protein – one of two proteins that make up the sweet taste receptor in mammals – has left cats unable to detect sweet-tasting compounds like sugars and carbohydrates.
It explains the indifference that domestic cats, lions, tigers, leopards and jaguars have been reported to show towards sweet foods. And it may also explain why they have evolved into such accomplished hunters, says Joseph Brand, professor of biophysics at Monell Chemical Senses Center in Philadelphia, US, and one of the study’s authors. “But it could be the other way around,” he suggests. “What came first: carnivorous behaviour or the loss of the T1R2 protein? With regard to the gene, is this a case of use it or lose it?” he asks.
Gene hunter
Looking down the family tree may provide clues. Brand has also found the mutant gene in cheetahs and tigers, and in their more distant relation, the hyena. So, although it seems clear that an ancestor of the big cats and the hyena must have possessed the faulty gene, Brand does not know on which branch of the evolutionary tree it first occurred. “Almost certainly the ancestral mammal would have been a successful hunter, or it would not have survived losing its sweet taste bud.
“And losing it may well have given wild cats a certain food niche that other animals can’t get into – most other animals need to hunt in packs, but big cats have developed the strength to hunt alone,” Brand told New Scientist. “But it’s a hard way of getting nutrition: they must hunt it, eat it, remove the nitrogen and only then can they use it.”
Carnivores’ diets are much less efficient than the omnivorous diets of many other large mammals, although parts of a hunted animal do contain carbohydrate - especially the liver - so it is possible that cats may be able to metabolise these energy stores.
Violent reaction
Coupled with the loss of sweet taste receptors in cats is a deficiency of sucrase in cats – the enzyme that digests sucrose. A consequence of this can be seen in cats that accidentally drink water containing sucrose. This makes them violently ill, but, since they cannot taste the sugar, they are unable to develop an aversion and so often drink more of the liquid, with the same results.
The mouth is not the only place where taste buds occur, Brand says. They also exist in the digestive tract and pancreas, where the sweet tasting receptors are also defective. Since the role of taste buds in places other than the mouth is unknown, the consequence of defective ones is also unclear, he says.
But, cats may be compensating for their lack of a sweet tooth. “Felines have very complex amino acid taste receptors. We have no idea what meats taste like to a cat: they may have sophisticated receptors to other taste stimuli that we just don’t know about,” Brand says.
"Our results account for the common observation that the cat lives in a different sensory world to the cat owner," comments team member Véronique Legrand-Defretin, director of the global feeding behaviour research programme at the Waltham Centre for Pet Nutrition in Leicestershire, UK.
How much insulin do you give him/her.....Mine gets 3 units twice a day.....comes running when I call him for his shot....go figure:-)
my cat could care less about catnip, but loves leather.
well, i don't know aobut sweets, but my cat will wolf down Pounce Treats ---those things are like Kitty Cocaine!
two words: cottage cheese.
There was a post here about a zoo somewhere where guys threw ciggies in the monkey cage and watched them sit around and smoke! The funny part is when the zoo employees came around they would hide them!
Excellent site...thank you!
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