Taste buds serve an important survival function; those tastes that an animal's buds determine are bad might be poisonous or harmful in some way. Yummy tastes typically mean the food is safe to eat. While animals taste similar flavors as humans -- bitter, sweet, salty, sour and umami, or tasting amino acids found in foods such as meats and cheeses -- not all animals have the same number of taste buds.
Carnivores, or animals who eat only meat as part of a normal diet, typically have fewer taste buds than omnivores. Lions, for example, have about 470 taste buds on their tongues, while humans, who eat fruits, vegetables and grain in addition to meat, average 10,000 taste buds. Most carnivores can detect bitter flavors, which helps them avoid rancid meat, but some, including big cats and water mammals such as dolphins, can't taste sweet flavors -- they lack the proper taste buds. Meat isn't sweet, so those taste buds don't help carnivores survive and are unnecessary. When your meals consist of pretty much one type of item -- meat -- you don't need as many taste buds.
Omnivores, or animals that eat both plant matter and meat, tend to have taste buds that allow them to taste all five flavors, including sweet, causing them to have more taste buds than carnivores. Pigs, for example, sport around 15,000 taste buds. The ability to taste sweets helps draw omnivores to carbohydrate sources, such as fruit, which carnivores hardly ever eat. Many birds are omnivorous, but they are an exception to the rule of having more taste buds than carnivores by having some of the lowest numbers of taste buds in the animal kingdom. Birds eat "meat" in the form of worms, grubs or insects, but they also enjoy berries, seeds and grains. But chickens, for example, typically have 30 taste buds or fewer. Parrots have a few hundred taste buds, but they don't rival the number of taste buds in other omnivores.
Herbivores, or animals that eat only plants, often have more taste buds than other land animals. Cows, for example, have about 25,000 taste buds. Like many herbivores, cows don't take a close look at their food -- they just munch away on what's close. The extra taste buds help herbivores quickly distinguish bitter tastes from dangerous plants that might be growing among safe vegetation. The sweet taste buds guide them to safer eating areas. Herbivores need salt to keep proper electrolyte balances and they don't get salt from meat like omnivores and carnivores, so the extra taste buds help them find salty substances to supplement their diets.
Fish tend to have more taste buds than land animals, and the taste buds aren't confined to their mouths. Many fish have taste buds on their skin. This helps them detect tastes through the water and determine which direction the taste is located. Catfish, who often swim and hunt in murky water where sight isn't very helpful, have the most known taste buds of any animal, topping out at 175,000.