Nutrients present in the feedstuffs are not completely
available to the animal body. Large portions of the nutrients
are excreted In the faeces because of being not digested In the
alimentary tract. Therefore, the digestibility of the feedstuff
is defined as the portion of a feed or nutrient of feed which is
not recovered In faeces, i.e., the portion which has been absorbed
by the animal. When the digestibility is expressed in
percentage it is known as digestibility coefficient. Digestibility
coefficients are calculated for dry matter, crude protein, crude
fibre, ether extract and nitrogen-free extract. Digestibility
of gross energy present in the food can also be determined. The
digestibility coefficients normally determined are the apparent
digestibility coefficients since the nutrients found in the
faeces contain small proportion of nutrients from the previously
utilized food In the form of mucosal debris, unspent enzymes ate