traditional poultry production has changed to a considerable industry after few decades. now, poultry industry is one of the main sectors to obtain the required protein for human consumption. prediction of the weight and number of eggs according to economic traits can improve the efficiency of production and the profit of producers. in present study, the weight and number of eggs in mazandaran ...

INTEREST in the genetic effects of irradiation on quantitative characters usually takes the form of two questions. Does irradiation effect a genetic change in the mean of quantitative characters such as human intelligence? Does irradiation induce genetic variance in quantitative characters that could be utilized by the plant or animal breeder for genetic improvement? Experimental data relevant ...

the data of this study were collected by indigenous chicken breeding centers in the west azerbaijan for 11 generations. the (co) variance components, heritability's, correlations between traits and breeding values were estimated by multi-trait animal model using wombat software. the genetic trends of traits over 11 generations of selection, using average function of breeding values per gen...

PURPOSE Sexual abstinence has become the primary response to adolescent pregnancy and sexually transmitted infection (STI) prevention. However, most abstinence programs are based on adult ideas of abstinence, and little is known about how adolescents themselves conceptualize sexual abstinence. METHODS In this qualitative study, we conducted semi-structured exploratory interviews with 42 adole...

Despite the widespread assumption that paternal investment is substantial in our species, previous studies have shown mixed results in relation to the impact of fathers on both offspring survival and reproductive outcomes. Using data from a large representative sample of British men, we tested whether father absence is associated with the timing of reproduction-related events among boys, while ...

Several hypotheses have been proposed to explain cyclic fluctuations in abundance of some small mammal populations. These hypotheses have been controversial, however, and there is no consensus among biologists as to why population cycles occur. In a demographically based model, we tested the potential influence of phase-specific changes in life history traits (age at maturity, fertility, juveni...

Background: Due to lack of detailed standards of sexual maturity in individuals with Intellectual, sensory and motor disability in Iran and the importance of timing of onset of puberty in these individuals, a study is necessary. By knowing the onset of puberty, physiologic and behavioral changes can be traced in these people, as well as the potential impact of the puberty on the underlying dise...

Young athletes frequently suffer from being seen as athletes first and children second. This has consequences for their legal, civil and human rights as children (Kelly et al., 1995) and for the way in which sport organisations choose to intervene on their behalf to protect them from physical, psychological and sexual abuses (Brackenridge, 1994). Sport careers peak at different ages depending o...

OBJECTIVE This research tests the influences of age, biological, and psychosocial factors on sexual expression in later life. METHOD The American Association of Retired Persons Modern Maturity Sexuality Survey collected data on diagnosed illnesses, treated illnesses, sexual desire, sexual attitudes, partner circumstances, and sexual behavior from 1,384 persons ages 45 and older. Ordered logis...