BACKGROUND We aimed to estimate the median ages at specific stages of sexual maturity stratified by excess weight in boys and girls. MATERIALS AND METHOD This was a cross-sectional study made in 2007 in Florianopolis, Brazil, with 2,339 schoolchildren between 8 to 14 years of age (1,107 boys) selected at random in two steps (by region and type of school). The schoolchildren were divided into:...

—Most anurans exhibit sexual size dimorphism (SSD). This morphological variation between the sexes may be attributed to different ages at maturity, growth rate, or longevity. We present the first data on age structure and growth pattern of Hypsiboas cordobae using skeletochronology, and analyze SSD considering age-specific differences in body size based on 71 individuals. Snout-vent length (SVL...

the aim followed in the present research was to investigate the effect of nine generations of divergent selection on some reproductive and egg production traits in japanese quail. the results indicated that selection for 4-week body weight, increased the age at sexual maturity of hw and of lw lines, in comparison with control, for about 7 and 3 days, respectively (p

introduction: genetic and health factors along with ethnicity and geographic location are factors that affect the time of puberty onset. the aim of the present study was to evaluate the mean age of onset of puberty and its stages in boys of yazd. methods: this cross- sectional study with random clustering sampling method was conducted on 1018 healthy 9-16 years old male students of yazd. all ca...

A crossbreeding experiment was conducted between the Sinai (SI), an indigenous Egyptian strain, and exotic Lohmann Brown (LB) breeds of chickens. total 790 chicks were produced in four genetic groups, namely SI x SI, LB LB, SI. The objective to estimate direct additive effect (gi), individual heterosis (hi), maternal (gm) for growth reproduction traits. Direct effects positive (P ≤0.01) bodywei...

We examined the effects of light intensity (LI) from photostimulation to 45 wk of age on egg production parameters and egg size characteristics and on ovarian and carcass morphology at sexual maturity and 45 wk of age in four layer strains. Floor housed pullets were raised in a light-tight facility from 1 d of age until housing in individually illuminated cages at 17 wk of age. Two white egg st...

Most Brazilian dairy production is conducted by small holders whose general management skills and feeding programs are often deficient. One common problem directly attributed to underfeeding is that heifers rarely reach sexual maturity before 15 months of age. Groups of growing heifers were treated to detect the effects of protein supplementation and antihelmintic treatment on sexual maturity. ...

Hon-Tsen Yu and Yao-Sung Lin (1999) Age, reproduction, and demography of the spiny rat (Muridae: Niviventer coxingi) in subtropical central Taiwan. Zoological Studies 38(2): 153-163. Annual reproductive cycles and demographic changes in a wild population of the spiny rat (Niviventer coxingi) in central Taiwan were studied. Reproductive status of the rat was investigated by autopsy and histologi...