COMPARISON OF SEASONAL PATTERNS OF GROWTH, VOLUNTARY FEED-INTAKE AND PLASMA-HORMONE CONCENTRATIONS IN YOUNG SAMBAR DEER (CERVUS UNICOLOR) AND RED DEER (CERVUS-ELAPHUS)

During 1991/93, young sambar (5 months old) and red deer (7 months old ) were confined indoors in individual pens in New Zealand and fed a pe lleted concentrate diet (12 MJ ME/kgDM; 2.9 % N) ad libitum for 21 mon ths. Seasonal patterns of voluntary feed intake (VFI), liveweight gain (LWG), scrotal circumference and plasma concentrations of prolactin ( PRL), luteinizing hormone (LH), testosterone (T) and progesterone (P) were compared using five stags and three hinds of each species. Red de er showed a strong pattern of seasonality, with high VFI and LWG in su mmer and low VFI and LWG in winter and with peak plasma T and scrotal circumference in stags in early autumn. Compared with red deer, sambar showed weaker seasonal patterns of VFI and LWG, with maximum values i n autumn and minimum values in spring. Over a complete 12-month cycle, sambar deer gained similar amounts of liveweight to red deer but cons umed substantially less feed, thus demonstrating a more efficient conv ersion of feed to bodyweight. Metabolizable energy (ME) requirements f or both maintenance and gain were substantially lower for sambar than for red deer. Scrotal circumference and plasma T values in sambar stag s attained their highest values during late autumn, winter and spring, but with a lower magnitude than peak values for red stags. Plasma PRL concentrations were seasonal in both species, with highest values in summer and lowest values in winter. Rapid increase of plasma P was fir st detected in red hinds in autumn and sambar hinds in spring when the y weighed 96 and 90 kg respectively, and were aged 17 and 14 months. R apid increase of plasma T was first detected in red stags in early aut umn and sambar stags in mid-autumn when they weighed 117 and 101 kg, a nd were aged 16 and 15 months respectively. It was concluded that samb ar deer had endogenous cycles of VFI, body growth and hormone secretio n, which were of lesser amplitude and with different seasonality from those of red deer. Young sambar deer were more efficient feed converte rs than red deer, and attained sexual maturity at an earlier age and l ower liveweight.