TISSUE MOBILIZATION RATES IN MALE FALLOW DEER (DAMA-DAMA) AS DETERMINED BY COMPUTED-TOMOGRAPHY - THE EFFECTS OF NATURAL AND ENFORCED FOOD RESTRICTION

The breeding season in temperate species of deer is characterized by t he rut, a period of intense sexual activity when the male eats very li ttle and competes for access to females. Males have been reported as l osing proportionately zip to 0.30 of live weight over a 6- to 8-week p eriod. The majority of the live-weight loss is accounted for in loss o f depot fat, with smaller losses in muscle reserves. The effects of bo dy composition, hormone status and season on these changes in fat and muscle reserves were examined in mature fallow bucks (Dama dama). The experiment was conducted in two stages, the 'rut' (February to May), a nd 'spring' (June to November). For the 'rut' period, bucks were rando mly allocated to either ad libitum feeding, entire (HiEnt), matched gr oup feeding, castrated (CAST), or entire bucks restricted to 7.6 kg dr y matter per week (LoEnt) treatment groups (no. = 4, 4 and 6, respecti vely). Three bucks from each of the HiEnt and LoEnt groups were select ed for the 'spying' period. Bucks were given food ad libitum until mid October, whereupon they were restricted to 2.5 kg dry matter er week for 4 weeks (SPRING). Group food intake and individual live weights we re measured weekly throughout both periods. Body composition was measu red by computed tomography on five and three occasions during the 'rut ' and 'spring' stages, respectively. Comparisons of the relative losse s of total fat and muscle relative to empty body weight (EBW) using th e allometric model (y = aX(b)) revealed significant treatment differen ces. HiEnt bucks had a high relative rate of fat and a low rate of mus cle mobilization (b = 5.23 and 0.38, respectively). Only the CAST grou p had lower (P < 0.1) b coefficient for fat than the HiEnt group at 2. 79. The LoEnt group teas the only group in which the b coefficient for muscle (at 1.07) was not significantly lower than 1.0. Visceral organ weight was lost at the same rate as EBW across all treatments. There was no net loss or gain of bone for any treatment group as the b coeff icients were not significantly different from zero. Fat depots were an alysed relative to the total fat depot using the allometric model. The HiEnt group displayed a pattern of fat mobilization whereby the exter nal depots were mobilized at the greatest relative rate and the intern al fat depots at the lowest rate ro coefficients were 1.86, 1.23 and 0 .68 for the subcutaneous, intermuscular and internal fat depots, respe ctively). CAST and SPRING groups were not significantly different from HiEnt bucks in the relative mobilization of fat depots. All fat depot s in the LoEnt group were mobilized at the same relative rate as total fat, as the b coefficients were not significantly different from 1.0.