Five male fallow deer, who were at the time of casting their first antlers, were maintained in a barn with artificial light control. The daylength sequence applied simulated an amplitude which was normal for 52" latitude, but each cycle lasted only 6 months. This photoperiod produced a doubling in frequency of morphogenetic and connected physiological values so that three complete antler cycles were reached within 19 months. Increase in levels of alkaline phosphatase and in concentrations of total-cholesterol (TC) and low-and high density lipoprotein cholesterol (LDL-C and HDL-C) followed the frequency of light alterations and correlated well with antler formation. On the other hand, an increase in neck circumference as well as increase of creatinine levels correlated well with the hard antler period of fertility as well.Adult male Cervidae living in temperate and arctic climates exhibit a pronounced annual cycle of secondary sex characteristics. These include, for instance, antler cycles and changes in neck circumference which both depend on annual variation of androgen levels (Lincoln, '71).Individual phases of antler cycle in adult fallow deer are characterized as followscasting period last third of April, first days of May; growing period from time of casting to time of velvet shedding; shedding period last third of August, first days of September; and hard antler period: from time of velvet shedding to casting time. In spikers, however, casting time occurs 2-3 weeks later than in adults (Ueckermann and Hansen, '68; Fischer, '85).Provided that individual bucks are maintained in a state of good health and that the optimal social relationships within the herd are secured, the timing of casting and shedding can be predicted very well. In some individuals casting and shedding will occur earlier than in others and vice versa (Fischer, '85). Similar results were described in whitetailed deer (Odocoileus virginianus) by Jacobson and Griffin ('83).Annual recurrence of these events as well as hormonal blood level variations are affected by seasonal fluctuations of day-length (Jaczewski, '54; Blackshaw, '77). The annual photoperiodic cycle could be manipulated by frequency alteration. Sika deer (Cervus nip pon) exposed to accelerated photoperiods adapted to such artificial changes and grew antlers more frequently than the controls (Goss, '69a).Studies which do report average concentrations of blood constituents often fail to recognize that the possibility of seasonal fluctuations may exist. Our previous research investigating the metabolic and physiological fundaments of antler cycle in fallow deer (Eiben and Fischer, '83, '84; Eiben et al., '84; Fischer, '85; Fischer and Schnare, '86; Schnare, '86; Schnare and Fischer, '87) demonstrated an annual periodicity of several connected blood values. For instance, the activity of alkaline phosphatase (AP) as well as the time courses of total cholesterol (TC) and low-and highdensity lipoprotein cholesterol &DL-C and HDL-C) exhibited an annual periodicity which was d...
