Hemoglobin is built up from protein and heme groups which give the blood its red colour . Hemoglobin transports oxygen and carbon dioxide between the lungs and other tissues in the body. Normally, a piglet has a hemoglobin value of 130-150 gram per liter blood, and the lower limit before anaemia appears is 80 grams per liter blood. The immune defense is also dependent upon the presence of iron in hemoglobin, since iron participates in different enzyme systems. When the piglet develops anaemia, it becomes pale and thicker around the neck.