We conducted an experiment to examine the effects of sex and food intake on growth, mass gain, and attainment of sexual maturity in Western Diamond-backed Rattlesnakes (Crotalus atrox). We also measured testosterone levels to determine whether testosterone might be involved in the male-biased sexual size dimorphism observed in this species. We collected neonate rattlesnakes and raised them in t...

Length, weight, structural index and sexual maturity in tambaqui Colossoma macropomum were analysed. 449 specimens were obtained from the commercial fishing fleet arriving at Manaus Harbour from the floodplain areas from May 1992 to July 1993. The objective of this study is to describe changes in structural index during one hidrological cycle and to interpret them according to the water level f...

The present study was undertaken to examine the effect of recombinant chicken leptin administered to fed ad libitum and feed-restricted immature chickens of a layer strain on ovarian development and the timing of sexual maturity. In the first experiment 11-week-old pullets (77 days of age) fed ad libitum were injected daily with leptin at four dose levels (4, 16, 64 and 256 microg/kg body weigh...

This study assessed whether selection for high growth in a challenging environment of medium salinity produces tilapia genotypes that perform well across different production environments. We estimated the genetic correlations between trait expressions in saline and freshwater using a strain of Nile tilapia selected for fast growth under salinity water of 15-20 ppt. We also estimated the herita...

A marine biological invasion is a natural process accelerated by human activities, and the crab Charybdis hellerii is an example of a globally widespread invasive species. This study evaluated color variation in C. hellerii and its relationship to the sex, size and sexual maturity of these crabs, and compared the efficiency of a freeware digital image-editing program with a commercially availab...

Social conditions experienced prior to sexual maturity influence reproduction later in life in many animals. In simultaneous hermaphrodites variation in mating group size influences reproductive investment. As the mating group size increases, reproductive resources devoted to the female function decrease in favor of the male function. Prior to sexual maturity many hermaphrodites have a protandr...

CONTEXT The time of life in which peak bone mass in the axial skeleton is attained has been the subject of considerable controversy, with estimates ranging from the time of sexual and skeletal maturity to the fifth decade of life. OBJECTIVE The objective was to examine whether dual energy x-ray absorptiometry (DXA) and computed tomography (CT) values for bone mass and bone density (BD) in the...

An experiment was carried out with SHAVER Starbro broiler parent stock from one day old to the point of peak production to investigate the growth, early laying performance and their adaptability during brooding, growing and early laying periods. The experimental period was divided into five phases, phase I (0 – 2 week), phase II (3 – 8 week), phase III (9 – 22 week), phase IV (23 – sexual matur...

In human populations, variation in mate availability has been linked to various biological and social outcomes, but the possible effect of mate availability on health or survival has not been studied. Unbalanced sex ratios are a concern in many parts of the world, and their implications for the health and survival of the constituent individuals warrant careful investigation. We indexed mate ava...