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 ...

An attempt was made to determine the cyclicity in yak through plasma progesterone estimation during breeding season as well as non-breeding season because silent or non-detected estrus is very common in this species. Blood samples were collected from yak (n = 8) during peak breeding season (July to November) and from the same animals in non-breeding season (February to March) at a two-day inter...

Vertebrates show a diverse array of social behaviors associated with territoriality. Field and laboratory experiments indicate that underlying themes-including mechanisms-may exist. For example in birds, extensive evidence over many decades has implicated a role for testosterone in the activation of territorial aggression in reproductive contexts. Territoriality at other times of the year appea...

This study was performed in adult male goats in which seasonal variations were abolished by rapid alternations of long days and short days. These treatments have been shown previously to prevent seasonal changes in the hypothalamo-pituitary axis and to maintain testis weight and sperm production at a high level. The experimental groups were exposed for 3 years to an alternation of either a 1 mo...

1. Explanations for the integration of migratory and non-migratory (resident) birds in the Neotropics have been complicated by the paradox that arthropod abundances are low when bird abundances reach their annual peak. The breeding currency hypothesis offers an explanation for this paradox by postulating that resident birds are limited in the breeding season by the availability of large arthrop...

Citation: Odom KJ, Omland KE, McCaffrey DR, Monroe MK, Christhilf JL, Roberts NS and Logue DM (2016) Typical Males and Unconventional Females: Songs and Singing Behaviors of a Tropical, Duetting Oriole in the Breeding and Non-Breeding Season. Front. Ecol. Evol. 4:14. doi: 10.3389/fevo.2016.00014 Typical Males and Unconventional Females: Songs and Singing Behaviors of a Tropical, Duetting Oriole...

The aim of this study was to evaluate the effect of semen collection method (artificial vagina compared to electroejaculation), season in which the semen was collected (breeding season compared to non-breeding season), freezing extender (Biladyl(®), Andromed(®) and skim milk based extender) and pre-treatment procedure (washing compared to non-washing) on post-thaw semen quality in buck. Ejacula...

The effect of gonadotropin releasing hormone (GnRH) treatment on the time of ovulation and the occurrence of follicular dominance during the non-breeding and breeding seasons (experiment 1), and on fertility after artificial insemination (AI) in the non-breeding season (experiment 2), was examined in Merino ewes. Oestrus was synchronized in 40 nulliparous ewes (experiment 1; n = 20, in the non-...

Testosterone (T) and its metabolites are important in the regulation of reproductive behavior in males of a variety of vertebrate species. Aromatase converts T to estradiol and 5alpha-reductase converts T to 5alpha-dihydrotestosterone (DHT). Male green anole reproduction depends on androgens, yet 5alpha-reductase in the brain is not sexually dimorphic and does not vary with season. In contrast,...

The wild ground squirrel is a typical seasonal breeder. In this study, using RT-PCR, western blot and immunohistochemistry, we investigated the mRNA and protein expressions of androgen receptor (AR), estrogen receptors α and β (ERα and ERβ) and aromatase cytochrome P450 (P450arom) in the medial preoptic area (MPOA) of hypothalamus of the wild male ground squirrel during the breeding season (Apr...