This study characterized seasonal changes in circulating LH and testosterone and in semen production and quality in the Northern pintail duck. Plasma LH and testosterone were measured in blood samples collected weekly throughout the year from eight males exposed to natural fluctuations in day length and temperature. Semen quality was evaluated weekly in these same males from April-June, the mon...

Ucar O. , M. Kaya, S. Yildiz , F. Onder , M. Cenesiz , M. Uzun: Effect of Progestagen/PMSG Treatment for Oestrus Synchronization of Tuj Ewes to be Bred after the Natural Breeding Season. Acta Vet. Brno 74, 2005: 385-393. The aim of this study was to investigate the effect of pregnant mare serum gonadotrophin (PMSG) and progestagen sponge on oestrus synchronization of Tuj ewes mated after breedi...

The objective of this study was to evaluate, over 2 consecutive years, the effects of acclimation to human interaction on performance, temperament, plasma concentrations of hormones and metabolites, and pregnancy rates of Brahman-crossbred cows. A total of 160 Braford and 235 Brahman x British cows were assigned to the 2-yr study. Approximately 45 d after weaning (August 2006) in yr 1, cows wer...

Background: Due to the seasonality reproduction of albino hamster (April to October in the Northern Hemisphere) and the need to produce blastocysts for research applications, producing and collecting blastocysts by natural mating in non-breeding season is complex in this species. In the present study in vivo blastocysts production and collection using super-ovulation and intrauterine inseminati...

BACKGROUND Possibly due to the small size of the olfactory bulb (OB) as compared to rodents, it was generally believed that songbirds lack a well-developed sense of smell. This belief was recently revised by several studies showing that various bird species, including passerines, use olfaction in many respects of life. During courtship and nest building, male European starlings (Sturnus vulgari...

Endocrine systems play critical roles in facilitating sexual behavior in seasonally breeding vertebrates. Much of the research exploring this topic has focused on the endocrine correlates of signaling behavior in males and sexual proceptivity in females. What is less understood is how hormones promote the expression of the often complex and highly selective set of stimulus-response behaviors th...

Overlapping moult and reproduction might be crucial for long-distance migratory birds, which are time-constrained to complete these energy-demanding functions before the onset of migration. However, proximate factors modulating the potential trade-off between moult and breeding, such as haemoparasite infection and stress, have not been studied in wild avian populations. We investigated the occu...

Aggression is an essential social behavior that promotes survival and reproductive fitness across animal systems. While research on the neuroendocrine mechanisms underlying this complex behavior has traditionally focused on the classic neuroendocrine model, in which circulating gonadal steroids are transported to the brain and directly mediate neural circuits relevant to aggression, recent stud...

Syferkuil Dam is situated 8 km NW of the University of the North and comprises a series of eight interconnected rectangular dams, having cement sides and mud bottoms. Throughout the experimental period, male and female adult specimens of the mouthbrooding tilapia, Oreochromis mossambicus were collected for further analysis. Aspects of the reproductive physiology of O. mossambicus that were inve...

The relationship between individual fitness and antioxidants and oxidative stress has come under increasing scrutiny of late. In particular, associations between oxidative balance indicators and reproductive success in the wild have been inconsistent in the limited prior work on this topic. Studies spanningmultiple seasons and antioxidant types are particularly lacking. Here, we examined associ...