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...

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...

Observations of the external morphology of wild-caught and captive male brown long-eared bats (Plecotus auritus) revealed a marked seasonal pattern of spermatogenesis, similar to that established by histological examination of other temperate-zone vespertilionids, with a peak in testes size in August and a lag between testicular growth and epididymal distension. This was followed by complete ce...

The purpose of this investigation was to determine the interrelationships of the various sexual and aggressive behaviors exhibited by Hereford bulls in sexual performance (serving capacity) tests and to determine the extent to which these interrelationships change with age (maturity). Correlation matrices were constructed for the frequencies of sexual and aggressive behaviors exhibited by two g...

BACKGROUND Antisocial personality and psychopathic traits have constantly been found to accompany criminal and aggressive behaviors, but little attention has been given to aspects of character maturity and its relation to such behaviors. The present study investigated (1) whether level of character maturity (low, medium, and high) is associated with amount of aggressive antisocial behaviors (AA...

age and growth of mesopotamian barb, capoeta damascina, were studied in the zayandehrud river, in central iran, from march 2007 to april 2008. among the 689 specimens studied, age groups in males ranged from 1+ to 9+ and that in females ranged from 1+ to 10+. the sex ratio (1m:1.6f) was not significantly different from 1:1 ratio. maximum fork length and weight was 39 cm and 1,115 g for males an...

Olfaction is an important sensory modality for mate recognition in many mammal species. Odorants provide information about the health status, genotype, dominance status and/or reproductive status. How and when odor profiles change during sexual maturation is, however often unclear, particularly in free-ranging mammals. Here, we investigated whether the wing sac odorant of male greater sac-winge...

The main aim of this research was to estimate the genetic and phenotypic parameters for productive and reproductive traits of Esfahan native chickens. Traits included body weights at hatch (BW1), 8 weeks of age (BW8), 12 weeks of age (BW12), and at sexual maturity (WSM)], age at sex maturity (ASM), egg number (EN), average egg weight (AEW) in the first 12 weeks of production, and egg production...

The objective of the present study was to investigate the polymorphism of prolactin promoter and cytosolicphosphoenol pyruvate carboxykinase (PEPCK-C) intron 3 to exon 3 regions, and its association with economictraits in native fowl of Yazd province. These traits consisted of body weight at 8 (BW8) and 12 (BW12) weeks of age, age at sexual maturity (ASM), weight at sexual maturity ...

Onset of sexual maturation is a trait of extreme importance both evolutionarily and economically. Unsurprisingly therefore, domestication has acted to reduce the time to sexual maturation in a variety of animals, including the chicken. In comparison with wild progenitor chickens [the Red Junglefowl (RJF)], domestic layer hens attain maturity approximately 20% earlier. In addition, domestic laye...