Natural gut strings are made from the intestines of a number of large animals, most commonly the cow and the sheep. Depending on what properties are required of the string, raw material may be taken from a number of places in the intestine, because the collagen in the intestine has varying amounts of orientation from layer to layer. It is more randomly oriented in the mucosa, which is more stretchy and has a lower tensile strength, than it is in the mucosa. Natural gut strings may even be made from threads of collagen harvested from different parts of the intestine.