Watching a cow eat grass can be quite boring. You might think there is nothing much going on, but while the cow seems to be standing around, her insides are working hard. For us, eating and digesting are pretty simple: all food goes in through our mouths, on to our stomachs and eventually out the other end. But in a cow, the food goes back and forth, back and forth, before it is finally digested.
1. When cows eat grass, they swallow it half eaten and store it in the first stomach, the rumen, where digestive fluids and bacteria soften the grass.
2. The grass then moves on into the second stomach, the reticulum. Here the grass is softened even more, and formed into little lumps, called cuds.
3. Together those first two chambers are called the reticulorumen and food can move back and forth between them.
4. The cud is then regurgitated, chewed slowly to completely mix it with saliva and to it break down even further. It then goes back into the the first two stomachs.
5. The food then passes into the third chamber, the omasum, where water and many of the inorganic mineral elements are absorbed into the blood stream.
6. The cud then moves on to the fourth and final stomach, the abomasum, which functions much like the human stomach.
7. In the udder, tint cells remove nutrients and water from the blood, changing them into milk.
8. Droplets of milk move through ducts into a holding tank called the cistern.
9. The udder is divided in quarters. Each quarter has a teat hanging from it.
10. The teats are connected to the cisterns.
11. When one squeezes the teat, milk comes out.