BACKGROUND One of the challenges faced by equine breeders is ensuring delivery of good quality semen doses for artificial insemination when the mare is due to ovulate. Single Layer Centrifugation (SLC) has been shown to select morphologically normal spermatozoa with intact chromatin and good progressive motility from the rest of the ejaculate, and to prolong the life of these selected spermatoz...

Males of many species invest resources in their offspring. For paternal investment to evolve, it must exhibit heritable variation. Using a standard half-sibling quantitative genetic design, we investigated whether genetic variation in male ejaculate size, a trait that affects female fecundity and copulation duration, are present in the seed beetle Callosobruchus maculatus. Ejaculate size was es...

Sexually selected male ejaculate traits are expected to depend on the resource state of males. Theory predicts that males in good condition will produce larger ejaculates, but that ejaculate composition will depend on the relative production costs of ejaculate components and the risk of sperm competition experienced by low- and high-condition males. Under some conditions, when low condition lea...

The study was performed on 4 609 ejaculates obtained from 32 boars, including 14 purebred and 18 two-breed crosses. The ejaculates were collected manually every 4-5 days. The study involved ejaculates collected from each boar from the first day of its insemination use until the day of semen depletion. Each ejaculate was assessed for the following physical parameters: ejaculate volume, sperm con...

While early models of ejaculate allocation predicted that both relative testes and ejaculate size should increase with sperm competition intensity across species, recent models predict that ejaculate size may actually decrease as testes size and sperm competition intensity increase, owing to the confounding effect of potential male mating rate. A recent study demonstrated that ejaculate volume ...

Several hypotheses have been proposed to explain the evolution of polyandry in species that provide nuptial gifts. When nuptial gifts are in the form of nutritional elements in the ejaculate and ejaculate size is correlated with male body size, females can accrue both direct (nutritional) and indirect (genetic) benefits from multiple mating. We examined remating decisions in females of the seed...

This review summarises the most significant findings related to the issue of the quantitative and qualitative indicators of stallion ejaculates, its processing when producing chilled insemination doses and the possibility of influencing the individual steps of the entire process. Artificial insemination, with cooled-storage semen, is increasingly used in horse breeding because it offers many ad...

background: determining the clinical significance of cardiac murmurs is widely considered in equine practice. pulmonary murmurs are commonly detected in athletic horses. echocardiography plays a leading role in assessment of these murmurs. objectives: echocardiographic evaluation of horses with pulmonary regurgitation and determining the importance of pulmonary valve murmurs. methods: a total n...

Recent theory and empirical evidence suggest a role for sexual conflict in the evolution of male ejaculates, including ‘nuptial gifts’. According to the sexual conflict hypothesis, the greater the probability of female remating, the stronger the selection on males to induce an elevated reproductive rate in their mates, even if this reduces some components of female fitness, such as survivorship...

Juhász J . , P . Nagy, M. Kulcsár , Gy. Huszenicza: Methods for Semen and Endocrinological Evaluation of The Stallion: A Review. Acta Vet. Brno 2000, 69: 247-259. Breeding soundness examination of stallions includes the examination of reproductive organs, behavior, quantity and quality of the ejaculate and function of the reproductive endocrine system. The paper reviews the current knowledge of...