Name:
Location: pretoria, gauteng, South Africa

i completed my Bsc (microbiology physiology) degree in 2005 at University of Limpopo, now im doing my honns in ecological informatics at university of the western cape.

Monday, May 15, 2006

DOES HERBIVOROUS DIET IMPOSE CERTAIN PROBLEMS FOR DIGESTION

Herbivorous animals eat only plants and it demands particular skills and structures to stick to one particular diet. Vegetables are not particularly nutritious and great quantities of material needs to be extracted to obtain enough calories to sustain large animals. In animals such as elephants their diet is so woody it takes a long time for them to digest their food. It takes an elephant two and a half days to digest its food and for most of the time the food will be in the stomach being stewed with digestive juices and bacterial broth. All plants contain cellulose and there is no animal that can digest cellulose what about rabbits? So animals depend mostly on stomach bacteria to break down cellulose by the process of fermentation (1).

All herbivorous animals have a four chambered stomach which allows most of them to digest foods which are low in nutrients. Most of the herbivorous animals develop big stomachs. Bovids, for example, elephants only digest half of what they eat in order to make up for a lack of efficiency of their digestive system. An elephant only digests 40 % of its food and the rest of the food leaves the elephants body undigested (4). Animals like cows take their food into their rumen, a chamber of the stomach which contains a particularly rich brew of bacteria. While the food is still in the rumen, the food is churned back and forth for several hours, and then the food is squeezed by a muscular bag, while the bacteria attach to the cellulose (3).

Ruminants have a stomach with four chambers rumen, reticulum, omasum and abomasums. The first two chambers (rumen and reticulum); food is mixed with saliva and separates into layers of solids and liquid material. Solid material is clumped together to form a bolus which is then regurgitated, chewed slowly to completely mix it with saliva which is then broken down into fibres especially cellulose. Cellulose is then broken down into glucose by symbiotic bacteria and protozoa. The fibre which was broken down which is now in a liquid form it is passed to the next stomach chamber, the omasum where the water is removed. After the food is digested it is then moved to the last chamber the abomasum. In the abomasum food is digested in the same way humans digest their food, and then sent to the small intestine where nutrients are absorbed (2).

Mature leaves contain a high amount of hard to digest cellulose and have relatively low energy. Some herbivorous animals tend to have long digestive tracts and slow metabolism (biochemical modification of chemical compounds in the living organisms and cells) rate. If an animal has slowed its metabolic rate it gets large or fat in order to accommodate the food which is in the stomach. So they solve the problem by growing big and having large stomachs. Many of the herbivorous animals depend on the symbiotic bacteria to release nutrients into their diet (1).

Herbivorous animals have to eat very fast (grab as much food as possible) and cautiously because if they relax they will be at great risk of being eaten by predators (animals which eat only meat). For example the African Giant Rat gets out of its burrow (hole) at night when there is no danger; it loads its cheek pouches with food and when the pouches are full then it goes back to its burrow. Herbivorous animals eat only one type of food (plants) so they do not get enough nutrients in their bodies like proteins.

Reference:

1. Wikipedia contributors. Herbivorous [internet]. Wikipedia, The Free Encyclopaedia; 2006 Apr 30, 00:26 PTA [cited 2006 May 12]. Available from: http://en.wikipedia.org/wiki/Herbivorous
2. Wikipedia contributors. Ruminants [internet]. Wikipedia, The Free Encyclopaedia; 2006 Apr 22, 23:58 PTA [cited 2006 May 12]. Available from: http://en.wikipedia.org/wiki/Ruminants
3. Wikipedia contributors. Bovid [internet]. Wikipedia, The Free Encyclopaedia; 2006 May 2, 05:19 PTA [cited 2006 May 12]. Available from: http://en.wikipedia.org/wiki/Bovid
4. Wikipedia contributors. Elephant [internet]. Wikipedia, The Free Encyclopaedia; 2006 May 11, 23:26 PTA [cited 2006 May 12]. Available from: http://en.wikipedia.org/wiki/Elephant

Lethabo Mosomane
CSIR
Pretoria
0001
Tel: 27 12 841 2133
Fax: 27 12 842 3676
mail: lmosomane@csir.co.za
http://lmosomane.blogspot.com

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