Background Gonadotropin-inhibitory hormone (GnIH), initially discovered in birds as a hypothalamic neuropeptide, inhibits the synthesis and release of gonadotropins via affecting GnRH neurons and gonadotropes. Therefore, it could be a key neuropeptide in regulating seasonal breeding in birds. The aim of the present study was to investigate the expression of GnIH in the hypothalamus of male and ...

The semen quality during the low (May-July) and the peak (September-November) breeding seasons in 18 Nili-Ravi buffalo bulls varying in age from 3 to 15 years was studied. Ejaculatory volume was higher (P < 0.05) in adult (3.03 ± 0.13 ml) and old (2.86 ± 0.13 ml) than young (2.51 ± 0.11 ml) bulls and during the low (3.44 ± 0.11 ml) than the peak (2.57 ± 0.90 ml) breeding season. Mass activity o...

Ž . Our understanding of insulin-like growth factor-I IGF-I in cervids has been limited mostly to its effects on antler Ž . Ž . Ž . Ž development in red deer Cer us elaphus , roe deer Capreolus capreolus , fallow deer Dama dama , and pudu Pudu . puda . Although IGF-I has been found to play a critical role in reproductive function of other mammals, its role in reproduction of deer is unknown. Th...

Because parental care is costly, a sexual conflict between parents over parental investment is expected to arise. Parental care behavior is an adaptive decision, involving trade-offs between remating, and consequently desertion of the brood, and continuing parental effort. If the main advantage of desertion is remating, then this will be a time constraint, because the deserting individual will ...

Although the amount of energy that males and females invest in reproduction is an integral component of theories explaining the evolution of particular mating strategies, few studies have actually determined the amount of energy that each sex allocates to reproduction. We compared how energy is expended by male and female Anolis carolinensis lizards during both the breeding and postbreeding sea...

In wild animal population studies, capture heterogeneity is likely to be prevalent and can reduce the accuracy of vital rate estimates. Here, we test how individual detection probabilities vary through the breeding season in a population of a cliff-nesting colonial seabird, the Black-legged Kittiwake (Rissa tridactyla). Specifically, we expected detection probability to be affected by changes i...

A similar proportion of beef cows and heifers exposed to estrous synchronization (ES) and artificial insemination (AI) became pregnant during the breeding season, compared with females bred via natural service breeding. Females in a breeding system that included ES and AI calved earlier in the calving season, compared with females bred with natural service, but no advantage was present for weig...

A central goal of population ecology is to identify the factors that regulate population growth. Monarch butterflies (Danaus plexippus) in eastern North America re-colonize the breeding range over several generations that result in population densities that vary across space and time during the breeding season. We used laboratory experiments to measure the strength of density-dependent intraspe...

The goal of this work was to correlate oxidative stress caused by reactive oxygen species (ROS) and DNA damage with classic semen parameters in spermatozoa and seminal plasma of fertile and subfertile stallions. Oxidation was measured in both lipids and proteins, using the thiobarbituric acid reactive species (TBARS) assay and the DNPH carbonyl groups assay, respectively. Sperm DNA damage was m...

In order to elucidate the relationship between androgens and the function of the muskrat (Ondatra zibethicus) scented glands during the breeding season, we investigated immunolocalization of steroidogenic enzymes P450scc, 3βHSD and P450c17 in the muskrat testes and scented glands. Nine adult muskrats were obtained in March (n=3), May (n=3) and July (n=3) 2010. Steroidogenic enzymes were immunol...