This study is aimed at evaluating the relationship between endogenous testosterone levels and antler development in male sambar deer (Rusa unicolor unicolor) inhabiting the Horton Plains National Park, Sri Lanka. Seven antler growth stages of sambar were documented based on phenotypic observations for the first time in Sri Lanka as (a) cast, (b) growing 1—single spike, (c) growing 2—antler fork into a Y as the second tine appears, (d) growing 3—velvet begins to harden as the third tine appears, (e) growth completed—velvet shedding begins, (f) hard antler, and (g) casting. Fecal samples were collected every month for a period of eighteen months from male sambar deer in different stages of the antler growth cycle, feeding in the wet patana grasslands of the park, and the fecal testosterone level was estimated by radioimmunoassay. Ten animals were randomly selected from each antler stage for the experiment. The results disclose that the highest concentrations of testosterone were recorded in the hard antler stage. Velvet shedding was preceded by an increase in the testosterone level, and it is the sudden drop in the testosterone concentration which triggers the antler casting. The casting stage corresponded with the lowest mean testosterone concentration. Although the study was able to conclude a clear relationship between the fecal testosterone levels of the male sambar deer in the Horton Plains National Park and their antler stages, there is no clear seasonality for the antler cycle.
This study examines the length of the estrous cycle in 16 Sambar deer hinds in National zoological gardens in Dehiwala and Kegalle, Sri Lanka (NZGDK) assessed with the use of changes in progesterone concentrations, along with the changes in the profile of this hormone and by the visual estrus manifestations. The objectives of the present study were to characterize ovarian activity throughout the estrous cycle and the non-pregnant luteal phase of captive sambar deer in Sri Lanka. These objectives were achieved with the use of radioimmunoassay (RIA) to measure fecal concentrations of progesterone and visual estrus manifestation. Fecal samples were collected from non-pregnant sambar deer hinds (aged 2–4 years)over the period of six months on daily basis, both during breeding and non-breeding seasons. Estrous cycles were recorded in non-pregnant females, based on fecal progesterone concentrations. The average estrous cycle length was 26.1±2.08 days (mean ± SEM) and 2.10 ± 0.51 days in the inter-luteal phase.The average fecal progesterone concentrations attained the peak mid-luteal values of 2.74 ng mL–1. There appeared to be variation in fecal progesterone amplitude between animals and between dates, but the low frequency of sampling prohibited confirmation of trends. Behavioral estrus was detected only when the average progesterone concentrations were less than 0.07 ng mL–1. However, not all periods of depressed progesterone secretion were associated with the observed estrus. Behavioral estrus was detected in hinds when progesterone concentrations were less than 0.07 ng mL–1; a subsequent rise in progesterone indicated ovulation taking place at this time.
11Testosterone concentration in fecal pellets of antler phases of male sambar deer in Horton plains National 12 park, Sri Lanka evaluated by Radioimmunoassay kit. The results obtained in this study were agreement 13 with identical research work carried out in other deer species with temperate ancestry. ABSTRACT 15This study establishes the relationship between testosterone concentration with the different antler phases 16 in male sambar deer (Rusa unicolor) inhabiting the Horton plains National Park, Sri Lanka (HPNP). Antler 17 growth of sambar was categorized into seven phases; Cast (C), Growing single spike (GS), Growing into a 18 Y as first tine appears (GIY), Growing Velvet begins to harden as third appears(GVT), Growth completed 19 -velvet shedding begins (VS), Hard antler (HA), Casting (CT) based on phenotypic observations. The 20 fecal samples were collected from 10 male sambar deer in each different phases of the antler growth cycle. 21Fecal testosterone level was estimated using radioimmunoassay (RIA). The results disclose that the dry 22 feces of sambar deer in hard antler phase have a highest mean testosterone concentration of 18.52± 01.87 23 ng g -1 . In the GVT phase the mean testosterone concentration was 09.50±2.01ng g -1 , while in the VS phase 24 the mean testosterone concentration increased to 14 ± 01.89 ng g -1 . The study also reveals a declination of 25 the testosterone concentration (06.80± 01.20 ng g-1) in CS phase. The C phase had a mean testosterone 26 concentration of 05.52± 0.84 ng g -1 .The fecal testosterone levels of the male sambar deer in HPNP changes 27 according to the phase of the antler cycle.28 29 30 31 32 33 Effect of testosterone on antler growth
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