Severe undernutrition in growing and adult animals

It is well known that prolonged undernutrition of immature mammals severely restricts growth, although some bone growth goes on even if the weight of the animal is not increasing. Rapid growth may be resumed with the restoration of unlimited food (McCay, Crowell & Maynard, 1935 ; McCance, 1960). Earlier workers, whose findings were reviewed by Jackson (1925, 1937), found that during recovery full stature was not always attained if the period of undernutrition was long and the animals were very immature. Pratt & McCance (1960) showed that the bones of cockerels continued to grow at a very reduced rate in spite of profound undernutrition but that an atypical bone matrix was formed. McCance & Widdowson (1955) showed that cockerels maintained at 200 g for 8 weeks were able to make a good recovery if given adequate food, and McCance (1960) found that this was so even after 6 months. Similar results were obtained in the present investigation, although the femur did not attain its proper length. The period of 6 months is significant, as it has been shown that the growth cartilages of the normal femur have disappeared well before this date (Pratt, 1961), so that in fact the normal femur should be incapable of further elongation by this time. This investigation is concerned principally with two problems. First, how does the bone from the stunted bird recover and, second, can a bone from a fully rehabilitated bird, even if it has failed to attain its proper length, be distinguished histologically from a normal bone?