Ostrich ejaculate characteristics and male libido around equinox and solstice dates

Mass Sperm Motility Is Correlated to Sperm Motility as Measured by Computer-Aided Sperm Analysis (CASA) Technology in Farmed Ostriches

Semen analyses have gained momentum in various livestock industries. However, in farmed ostriches, semen analysis is still in its experimental stage, and males are not screened for sperm quality before breeding. This study investigated the correlations between computer-aided sperm analysis (CASA) technology and the traditional, yet affordable, mass sperm motility score. Semen was collected from nine South African Black ostrich males (mean age ± SD: 5.25 ± 1.21 years), using the dummy female method for 5 consecutive days monthly, for 8 months. Mass sperm motility scores were recorded on a scale of 1−5 (1: little to no sperm movement; 5: rapid sperm movement). The CASA traits recorded were: total motility (MOT), progressive motility (PMOT), curve−linear velocity (VCL), straight-line velocity (VSL), average path velocity (VAP), amplitude of lateral head displacement (ALH), linearity (LIN), straightness (STR), wobble (WOB), and beat-cross frequency (BCF). The results revealed positive correlations between mass sperm motility and PMOT, MOT, VCL, and VAP ranging from 0.34 to 0.59 (p < 0.0001). In contrast, negative correlations were recorded between mass sperm motility and LIN, STR, and BCF, with correlations ranging from −0.20 to −0.39 (p < 0.0001). VSL, ALH, and WOB were not correlated to mass sperm motility (p > 0.05). Ostrich farmers may thus be able to evaluate sperm motility reliably and potentially select breeding males by using the affordable mass sperm motility scoring method. Determining the correlation between these methods and fertility after artificial insemination or natural mating is however needed.

A comparative study of libido in drakes: from phenotypes to molecules

Low fertilization rate is the main reason to limit the development of artificial insemination (AI) technology in ducks. However, the libido of male livestock has been confirmed to be related to semen quality and fertilization rate, and we found that the libido of drakes was different. Thus, the research on the libido of drakes may be the key to further develop and apply AI technology. In this research, we established the first scoring standard for libido evaluation in drakes based on the performance of drakes during training period. Phenotypically, the body weight of high libido group was lighter than that of the other groups, while the weight of testis and epididymis in the high libido group was higher than that in the low libido group. Furthermore, we constructed the first expression profile of hypothalamus, pituitary, testis, and epididymis of drakes with high or low libido. There were 2, 1822, 214, and 892 differentially expressed genes (DEGs) in hypothalamus, pituitary, testis, and epididymis. The expression and sequence of Translocation Associated Membrane Protein 2 (TRAM2) were different in high and low libido drakes, indicating that it may be a candidate gene related to drake's libido. The estrogen, prolactin, and oxytocin signaling pathways were all activated in the pituitary of the low libido group. Meanwhile, the metabolic and oxidative phosphorylation pathways were enriched by DEGs in pituitary, testis and epididymis. Our research reveals that the difference in metabolic may cause changes in body weight of drakes, resulting in altered hormone levels and oxidative phosphorylation of gonad, which negatively affects libido and spermatogenesis in drakes. These results provide novel insights into the avian libido and will help better understand the underlying molecular mechanisms.

Extreme temperatures compromise male and female fertility in a large desert bird

Temperature has a crucial influence on the places where species can survive and reproduce. Past research has primarily focused on survival, making it unclear if temperature fluctuations constrain reproductive success, and if so whether populations harbour the potential to respond to climatic shifts. Here, using two decades of data from a large experimental breeding programme of the iconic ostrich (Struthio camelus) in South Africa, we show that the number of eggs females laid and the number of sperm males produced were highly sensitive to natural temperature extremes (ranging from -5 °C to 45 °C). This resulted in reductions in reproductive success of up to 44% with 5 °C deviations from their thermal optimum. In contrast, gamete quality was largely unaffected by temperature. Extreme temperatures also did not expose trade-offs between gametic traits. Instead, some females appeared to invest more in reproducing at high temperatures, which may facilitate responses to climate change. These results show that the robustness of fertility to temperature fluctuations, and not just temperature increases, is a critical aspect of species persistence in regions predicted to undergo the greatest change in climate volatility.