4.1. Reproduction
Sexual maturity, form a physiological point of view, is reached at an age of 1 1/2 years, in both sexes (Couturier, 1962). Usually however, age of primiparity in females is delayed to a later age in response to population density. In high density populations, females give birth for the first time at 3-4 years of age, while in recently established populations it is possible to observe pregnant females as young as 2 years old (Martinot et al., 1983; Michallet et al., 1994, 1996). The analysis of progesterone levels in the blood in Alpine ibex females at different ages, confirmed that young females under two years of age usually do not have any ovarian activity (mean level of progesterone in the blood= 0.73 nmol/l ± 0.44, n= 9). The potential also for yearling females to reproduce was however confirmed by a case of a female 1 1/2 years old, with a high level of progesterone in the blood (22.2 nmol/l), almost certainly linked to a pregnancy in progress (Gauthier et al., 1994).
In captivity, female Alpine ibex present a polyestrous seasonal cycle, each of which lasts about 20 days (Stüwe e Grodinsky, 1987). If fecundated, the female completes pregnancy
in an average of 167 days (± 3 days); 165-170 following Couturier (1962). If the female is not fecundated, she returns in heat in a following cycle, about one month later: this may explain the observation of late births, which can happen until the beginning of July (V. Peracino, pers. com.).
In captivity females reproduce from 1 to 15 years and give birth to an average of 0.78 kids per year; Twins are born with a mean frequency of about 0.2 (Stüwe & Grodinsky, 1987).
In natural conditions the birth rate is much lower and appears to be negatively related to population density. In the Gran Paradiso National Park, the mean value of the birth rate index, based on 20 years of censuses, is 0.42 (± 0.06 SD, Min= 0.2, Max= 0.5, Bassano et al., 1992).

4.2. Haematology
Haematological screenings of Alpine ibex and domestic goats are identical. This evidence confirms the phylogenetic proximity of the two species. In the litterature, contrasting values are reported for the total number of erythrocytes, leukocytes and for the leukocyte formula, probably because the different origin of the tested animals. Gauthier et al. (1994) analysed blood samples taken from 138 Alpine ibex captured in nature and report the following haematological values (mean values in millions/mm3 ± standard deviation: Erythrocytes= 13.55± 3.01; Leukocytes= 9540± 5700; Leukocyte formula (mean values in percentage ± standard deviation): Neutrophils= 35.9± 13.4, Eosinophils= 8.7± 7.7, Basophils= 1.5± 1.7, Linfocytes= 50.4± 13.9, Monocytes= 3.5± 3. Different results have been obtained from Alpine ibex in captivity (Cook et al., 1986).
From the biochemical point of view, the concentrations of cortisol and muscular enzymes (CPK= Creatin-Phospho-Kinase e LDH= Lactate Dehydrogenase), have been particularly studied, in order to measure the reaction of Alpine ibex when facing different environmental stress conditions (Sartorelli et al., 1989; De Meneghi et al., 1990; Sartorelli et al., 1991).