The Grass Doctor

why are animals like the buffalo so big if they only have a diet of grass?

trting to detrmine if thee is a signifcant nurtional value to the diet of these large animals throughout history that do not eat meat.

Public Comments

1. They eat tons of it.....
2. Its because they eat soo much and also chudd(is this the right word?) so much! They eat all the time and store some food in the mouth, so that they can eat it later!
3. cause they are herbivores
4. Do you have any idea how much grass they eat!!
5. They eat a lot of grass and they get little exercise!
6. Pound for pound, there isnt anything to compare to meat (assuming of course you are adding in the fat, and the tasty, ever-surprising intestines and stomachs of the prey). But, food for a carnivore is dangerous-you cant get fat and slow, you want to keep the meal frequencies to a minimum, and each meal comes with some exercise-thus big canivores only eat once or twice a week at best. Herbivores eat for hours and hours every day. No, the food is not highly nutritious, especially in terms of fat and protein content-but there is a whole lot of it, a long time to eat and digest it, and no worries about over-eating and getting fat, really. You know, the eating patterns are why herbivores tend to be much more aggressive, dangerous animals that carnivores- Think bull moose, bull elephants, hippos, rhinocerous etc- They are much more aggressive and dangerous to be around than a corresponding lion or wolf. Herbivores can afford to get quite injured, and still recover cause their food doesnt move around and try to get away. A tiger breaks it's foot, or gets a terribly torm muscle, and it will likely starve, so large carnivores are generally very wary of getting into fights.
7. It's not so much that there is a great nutritional value to grasses, in fact it is the opposite. They don't digest a great deal of the hard cellulose walls of grass. They need to eat a great deal of grass to make up for this deficiency. In fact, I have read that scientists think that herbivourous dinosaurs were so big b/c their plants were even less nutritious than today. So they were like big fermenting vats walking around on 4 legs.
8. I don't know what the prevailing ideas on this are, but my guess is that their size has nothing to do with what they eat, since there are lots of small herbivores. The two possible selective forces I can think of would be size provided a defense against predators and that as a result of male-male competition, male size was strongly selected for and female size followed along. These are just guesses.
9. Actually, when you're eating low quality food like grass, it actually pays to be big in body size. Cows/Bison/Buffalo with their huge stomachs and cud chewing processing plant are able to collect large quantities of grass and process them for as much nutrition as can be wrung from the hard-to-digest plant fodder. Smaller animals can't gather as much material at one time, and so are unable to get as much nutrition from a single grass meal as a cow can. They either have to eat higher quality forage, or come up with a different strategy. It's sort of like how Wal-Mart can afford to run all those huge stores even though the stuff they sell isn't the highest quality - volume. Some other critters, like horses, are not able to process grass as efficiently as cows because they are not ruminants, and don't chew their cud. Instead, horses survive by getting whatever nutrition they can out of their fodder, and sending it through the system as quickly as possible. Using this system, they can actually survive on lower quality fodder than the cows. They poop a lot, but get their nutrition by getting a small amount of nutrition from each portion of a lot of fodder. This strategy is taken even farther by elephants. Using a HUGE food storage system, an elephant can take in vast quantities of very poor quality fodder, get what nutrition there is out of it, and send it on through the system as poop. A smaller animal couldn't survive eating the low quality food elephants eat. Because the efficiency of a low-quality herbivorous diet tends to increase as body size increases, there is an evolutionary trend towards large body size in many herbivore lineages. The largest dinosaurs were herbivores, and so are the largest land mammals. The baleen whales could almost be considered grazing herbivores of this style as well. Even though they eat tiny krill and zooplankton, they are able to maintain their large bodies by eating HUGE quantities of these little critters.
10. aaaw thats cute! Yeah now that you mention it I wonder too!