In the first few days following birth, the mother cat lies on her side to make her teats accessible to her young. The kittens' first attempts at suckling produce not milk but colostrum, a substance different from milk in appearance and composition. In particular, colostrum contains numerous antibodies that the kitten absorbs in massive quantities during the first sixteen hours of life. These antibodies protect the kitten from germs in its environment from a few days to a few weeks. A few days later, the mother begins producing milk for her nursing kittens. Like colostrum, feline mother's milk is high in antibodies. For this reason, when kittens do not receive colostrum, they should be given feline mother's milk within sixteen hours of birth so that they can absorb the antibodies. Still, colostrum is always preferable, since, in addition to antibodies, it contains other elements lacking in milk.