heritability, environmentaland genetic correlations between body weight at hatch (bw0), eight (bw8) and twelve (bw12) weeksof age, body weight at sexual maturity (bwm), age at sexual maturity (afe),the weight of the first egg laid by the hen (ewm), the mean egg weight from 28 to 32 wks (ew28-32) and egg numbers (ens) were estimated by the restricted maximum likelihood method under an animal mod...

A target BW is often used to estimate sexual maturity in beef heifers. The target BW, a percentage of mature BW, is generally an average for the breed, herd, or both. Heifer development is done in groups or herds, and not all heifers respond similarly to the same development regimen. Generally, heifers fed at a higher plane of nutrition gain more BW and tend to have increased pregnancy rates, b...

In many animal species, males and females attain different adult body sizes. The processes underlying such sexual differences are undoubtedly complex and may involve an interplay between adaptive, exaptive, and nonadaptive genetic influences on the one hand and environmental variables on the other. For example, large body size may be shown by males because genes for that character confer a sele...

Paedomorphosis is an alternative process to metamorphosis in which adults retain larval traits at the adult stage. It is frequent in newts and salamanders, where larvae reach sexual maturity without losing their gills. However, in some populations, larvae overwinter in water, while remaining immature. These alternative ontogenetic processes are of particular interest in various research fields,...

As the U.S. EPA begins its program to test endocrine-disrupting effects of pesticides, researchers caution that routine screening methods could distort results [EHP 115:1717–1726; Thigpen et al.]. The team discovered that some commercially available rodent diets can cause early sexual maturation similar to that induced by chemical endocrine disruptors. Furthermore, one rat strain commonly used ...

Human faces can motivate nurturing behaviour or sexual behaviour when adults see a child or an adult face, respectively. This suggests that face processing is tuned to detecting age cues of sexual maturity to stimulate the appropriate reproductive behaviour: either caretaking or mating. In paedophilia, sexual attraction is directed to sexually immature children. Therefore, we hypothesized that ...

in order to study the effect of water deficit stress at different growth stages on yield and seed oil quality of rapeseed cultivars, a field experiment was conducted as split-plot in a randomized complete block design arrangement with three replications in 2009-2010 growing seasons in abarkouh in iran. four levels of irrigation were located in the main plot including, (i1) normal irrigation bas...

since sturgeons have no external sexual dimorphism and there are no external markers to determine sex, internal examination of the gonads should be used to sex identification. the present study describes the biopsy method and histological observations of the gonads of great sturgeon (huso huso) in both sexes at different age classes. sex and maturity stages of 226 great sturgeons were identifie...

The effects of early thermal environment on growth, age at maturity, and sexual size dimorphism in Arctic charr (Salvelinus alpinus) are investigated. This study is a 654-day long rearing trial split into two sequential experimental phases termed EP1 EP2 lasting 315 339 days, respectively. started the end yolk sac stage when fish were divided three groups reared different target temperatures (7...