184 Discussion 



diminution in antler size. A picture of such a series is presented by 

 H. E. Anthony (1929). In view of the concept I have outlined of the 

 control of the antler cycle, I attribute the decline of the antlers in 

 senescent deer to a weakening of the hormonal regulation by the gonads 

 and anterior pituitary. 



Besides becoming extremely small with advanced age, the antlers are 

 frequently deformed and permanently covered by velvet, and are no 

 longer shed (cf. Rorig, A. 1899; 1907). These features also point to a 

 slackening of the hormonal regulation. The permanent retention of the 

 antlers in velvet coincides with the effects upon antlers produced by 

 removal of the gonads of adult deer. On the other hand, the diminution 

 in their size points to decline in the pituitary factor. 



Zuckerman: Is there another factor involved — the factor of nutrition? 



Wislocki: Nutrition does play a vital role as a factor in the growth of 

 antlers with respect, particularly, to their size and weight. In a privately 

 kept herd of red deer, in Czechoslovakia, supplemental feeding of the 

 herd with various foods rich in calcium, phosphorus and vitamins, 

 induced the growth of antlers of incredible size (Vogt, 1937). 



Deer ordinarily consume grasses, leaves, shrubs, lichen, berries and 

 other plants from which they usually obtain sufficient minerals. If their 

 needs are not fully met, they may adopt peculiar habits. Murie (1935) 

 describes the phenomenon in late winter of Alaska-Yukon caribou eating 

 the shed antlers. Individual deer were also reported as eating the velvet 

 and gnawing at one another's antlers just before shedding. 



Zuckerman: May I just add one further fact to that story? Duck- 

 worth, at the Rowett Research Institute i n Scotland, has shown that 

 major osseous changes occur in the pregnant ewe, including thinning of 

 the bones and complete loosening of the teeth. By the time the animals 

 are ready to lamb under the very hard winter conditions that prevail 

 in Scotland, their jaws do not fit and there may be complete mal- 

 occlusion. When the grass-growing season starts again the tooth again 

 becomes held in the alveolus. 



Wislocki: With respect to the phenomenon of shedding of the antlers, 

 Waldo and I (Waldo and Wislocki, 1951 ; Wislocki and Waldo, 1953) 

 proposed a new concept of the process of shedding, which recognized 

 growth and proliferation, rather than death, of the tissues at the antler- 

 pedical junction as the major factor responsible for the loosening and 

 shedding of the antlers. We attributed the proliferative changes, 

 accompanied by local decalcification, to a hormonal "antler-growth" 

 stimulus, probably of pituitary origin. Thus, the shedding of the antlers 

 does not appear to be a regressive phenomenon dependent solely on 

 poor nutrition, as would seem to be true of the changes in the teeth of 

 pregnant ewes. However, in connection with pregnancy, it should be 

 recalled that in reindeer, in which the females also have antlers, these 

 are shed just after the termination of pregnancy. This suggests the 

 possible role, at that period, of hormonal changes in the induction of 

 antler-shedding. Nevertheless, it is also probable that metabolic 

 changes in calcium and phosphorus should have occurred during the 

 course of gestation. 



