Classification of ostrich sperm characteristics

Abstract

The success of assisted reproduction techniques is dependent on a sound foundation of understanding sperm characteristics to evaluate so as to improve semen processing. This study offers a descriptive basis for ostrich semen quality in terms of sperm function characteristics (SFC) that include motility, measured by computer assisted sperm analysis CASA (SCA(®)), viability (SYBR14/PI) and membrane integrity (hypo-osmotic swelling test). Relationships among these SFC's were explored and described by correlations and regressions. Certain fixed effects including the dilution of semen, season, year and male associated with semen collection were interpreted for future applications. The seasonal effect on sperm samples collected throughout the year suggested that it is prudent to restrict collections to spring and summer when SFC's and sperm concentration are maximized, compared to winter when these aspects of sperm quality are suppressed. Dilution of ejaculates helped to maintain important SFC's associated with fertilization success. The SFC's and sperm concentration varied among males, with specific males, having greater values for the percentage of motile (MOT) and progressively motile (PMOT) sperm, as well as sperm velocity (VCL, VSL, VAP) and linearity (LIN) variables. Males may thus be screened on these variables for inclusion in an artificial insemination (AI) programme to optimize fertility success rates.

Ostrich ejaculate characteristics and male libido around equinox and solstice dates

“…Ejaculates collected around the summer solstice as well as spring and autumn equinoxes were highly concentrated and contained higher number of spermatozoa than those collected around the winter solstice. This finding is consistent with previous studies that reported that semen samples collected during the spring, summer and autumn months contain a higher sperm concentration than samples collected in winter (Bonato et al 2014, Smith et al 2016. This suggests that sperm output in ostriches may be influenced by a range of environmental variables such as daylength, rainfall and temperature (Ball and Ketterson 2008).…”

“…Sperm motility traits were measured using the Sperm Class Analyzer® (SCA) version 5.3 (Microptic S.L., Barcelona, Spain) with a Basler A312fc digital camera (Basler AG, Ahrensburg, Germany) mounted on an Olympus BX41 microscope (Olympus Optical Co., Tokyo, Japan) equipped with phase contrast optics. An aliquot of neat semen at a concentration of 20 × 10 6 sperm cells/mL was diluted in 245 μL of standard motility buffer containing sodium chloride (150 mM) and TES (20 mM) with 2% male specific seminal plasma (Smith et al 2016). The tube containing the diluted semen was placed in an incubator at 38°C for 1 min, before loading 2 μl of the diluent onto a pre-warmed slide (at 38°C ), covered gently with a cover slip (22 × 22 mm) and allowed to settle for 20 s prior to recording.…”

“…An aliquot of neat semen at a concentration of 20×10 6 sperm cells/mL was diluted in 250 μL of a standard saline solution (NaCl/H 2 O) adjusted to 25 mOsm (Smith et al 2016). After dilution, 2 μl of the semen diluent was loaded onto a pre-warmed slide (at 38°C), covered gently with a glass cover slip (22×22 mm) and allowed to settle for 20 s prior to recording.…”

“…Previous studies on ostriches have highlighted that traits such as sperm output, sperm viability, morphology and motility as well as male libido appear to be affected by factors such as season, male age and the frequency of collections (Rybnik et al 2012;Bonato et al 2011Bonato et al , 2014. These studies have however used a small number of individual animals or a subjective method to measure sperm motility, which may have produced less accurate results than using more recent objective computer assisted methods (Mocé and Graham 2008;Smith et al 2016;Farooq et al 2017Farooq et al , 2018. Smith et al (2016) recently reported sperm motility characteristics evaluated by computer-aided sperm analysis as well as sperm membrane integrity during the conventional ostrich breeding season (May to December).…”

“…These studies have however used a small number of individual animals or a subjective method to measure sperm motility, which may have produced less accurate results than using more recent objective computer assisted methods (Mocé and Graham 2008;Smith et al 2016;Farooq et al 2017Farooq et al , 2018. Smith et al (2016) recently reported sperm motility characteristics evaluated by computer-aided sperm analysis as well as sperm membrane integrity during the conventional ostrich breeding season (May to December). No information on the above parameters is however available beyond confines of the standard breeding season (January-April).…”