The influence of nutrition and photoperiod on the growth, development and endocrine status of captive red deer and Soay rams
Scottish red deer (Cervus elaphus scoticus) are smaller in size and mature later than many continental subspecies. Previous investigations at the Rowett Institute have shown that when Scottish red deer are fed well they grow almost as large as European deer, so the differences between subspecies appear principally determined by the environment. To test this, one group of 6 stag calves was fed to appetite while a second group of 6 was offered 70% as much (on a metabolic body weight basis) during the winter and both groups fed to appetite during the following summer. After the first winter the restricted group were lighter and skeletally smaller than the unrestricted group. Despite compensatory growth during the summer significant differences in weight and size remained at the end of the period of feeding to appetite. This pattern was repeated during the second and third years of the study, Plane of nutrition bad little effect on size and composition of antlers but had profound effects on the timing of growth of the first antlers. Although the restricted stags were less fat than the unrestricted stags both groups showed the same relationship of fat content of the body to empty body weight. The restricted plane of nutrition delayed the growth and moult of wool and hair but did not affect length of either. The restricted plane of nutrition exerted only slight effects on levels of testosterone, oestradiol 17 beta,prolaotin and thyroriue and no effect on the timing of their cycles. A field study on the effect of winter undernutrition on stag calves at Glensaugh Deer Farm gave similar results. Cycles of body weight and food intake were shown to be of smalleramplitude in captive hinds than stage. Superior cervical ganglioneotomy of Soay rams diminished the amplitude of cycles of food intake and growth as much as cycles of reproduction but failed to abolish either.