Spermatozoa Characteristics in Six Psittacine Species Using Light Microscopy

Karyotype depends on sperm head morphology in some amniote groups

The karyotype of an organism is the set of gross features that characterize the way the genome is packaged into separate chromosomes. It has been known for decades that different taxonomic groups often have distinct karyotypic features, but whether selective forces act to maintain these differences over evolutionary timescales is an open question. In this paper we analyze a database of karyotype features and sperm head morphology in 103 mammal species with spatulate sperm heads and 90 sauropsid species (birds and non-avian reptiles) with vermiform heads. We find that mammal species with a larger head area have more chromosomes, while sauropsid species with longer heads have a wider range of chromosome lengths. These results remain significant after controlling for genome size, so sperm head morphology is the relevant variable. This suggest that post-copulatory sexual selection, by acting on sperm head shape, can influence genome architecture.

Assessment of Sperm Viability and Computer-Assisted Motility Analysis in Budgerigars (Melopsittacus undulatus): Effect of Several In Vitro Processing Conditions

In order to preserve endangered psittacine species, more basic and applied research in reproductive biology is required. Assisted reproductive technologies such as artificial insemination play an important role in parrots species conservation programs to overcome the problem of infertile eggs and male infertility. The aim of this study was to define an effective in vitro protocol in order to standardize the sperm quality evaluation in psittacines, studying Melopsittacus undulatus as model species. Semen was collected from twenty adult males by massage technique from May to June. Sperm concentration was measured by the spectrophotometric method. Sperm quality (sperm membrane integrity (SMI), motility, and kinetic parameters) was assessed on fresh semen. Three different experimental protocols were performed to compare the effects of various processing conditions on SMI, motility, and kinetic parameters. In protocol 1, test was performed by Lake extender with three different pH, 7.4 versus 8.2 versus 8.4, and two different equilibration temperatures after dilution of fresh semen (4°C versus 25°C). In protocol 2, two dilution rates of semen after collection were valuated, 1 : 3 versus 1 : 4, as well as three different semen storage temperatures (4°C versus 25°C versus 38°C) before sperm motility analysis with the computer-assisted sperm analysis (CASA). In protocol 3, two different Makler chamber temperatures (38 versus 41°C) during motility analysis were tested. A significant progressive improvement in spermatozoa motility and kinetic parameters was registered with pH 8.4. Progressive motility and all kinetic parameters were higher at 4°C equilibration temperature. Straightness (STR) kinetic parameter was better with 1 : 4 dilution rate. Total motile sperm was higher in 41°C Makler chamber. In this study, for the first time, the effects of different processing protocols on psittacines seminal quality analysis were investigated. Significant differences conditioning the effectiveness of analysis protocols have been described.

Viability assessment of spermatozoa in large falcons (Falco spp.) using various staining protocols

Viability assessment is an important part of semen analysis, and various live/dead staining protocols have been used in semen of avian species. Results of live/dead count differed between dyes, staining protocols and bird species, impeding comparability between studies and requiring species-specific comparisons of viability stains. In raptor semen, similar comparisons are absent. Thus, the aim of the present study was to compare eight conventional viability stains. Eosin blue 2% [EB], eosin blue 2% with the addition of 3% sodium citrate [EB2], eosin blue-nigrosin 5% [EBN5], eosin yellow-nigrosin 5% [EYN5], eosin yellow-nigrosin 10% [EYN10], eosin blue-aniline blue [EBA], eosin yellow-aniline blue [EYA] and bromophenol blue-nigrosin [BBN] were evaluated in comparison with the fluorescence stain SYBR^® Green-propidium iodide [SYBR-PI] in spermatozoa of falcons. The comparison was performed using conventional light microscopy which is applicable in breeding centres, veterinary practices and field studies. Additionally, live/dead stains were correlated to motility values of the same samples to validate sperm viability. Light microscopy using EB and using SYBR-PI enabled an effective and clear differentiation between alive and dead spermatozoa of falcons. Motility values correlated significantly and strongly with EB only (r = .629; p < .001), but not with any other stain used in the study. Therefore, our results suggest EB as the most suitable stain for viability assessment in the semen of large falcons.

Semen analysis and successful artificial insemination in the St. Vincent amazon (Amazona guildingii)

The St. Vincent amazon (Amazona guildingii) is an endemic parrot on the Carribean island St Vincent. Due to poaching, trade, natural events such as hurricanes and habitat loss the species declined severely throughout the 20th century to a total number of 487 adult individuals and is currently regarded as vulnerable by IUCN. Captive breeding is attempted in terms of species conservation, but reproduction rates have been low due to reproductive problems such as mate aggression, asynchronous reproductive activity and infertile eggs. The aims of the present study were; firstly, to evaluate whether semen analysis might help to assess the fertility of males and to detect potential reasons for infertile eggs; secondly, to increase the number of offspring using artificial insemination, and as a future effect, to increase the presence of genetically valuable males in the ex-situ breeding population. For semen collection electric stimulation was used in 15 mature and healthy St. Vincent amazons with a success rate of 89% (202/227 attempts) in 14/15 males. Quality assessment of the semen included the evaluation of volume, pH, color, consistency and contaminations of the ejaculate, as well as estimation of motility, viability, morphology, concentration and total count of spermatozoa. Semen pH ranged from 6.7 to 7.5. Median sperm motility was 50% and median progressively forward motility 40%. Mean sperm concentration (x¯ ± SD) was 21,313.5 ± 22,408.8 spermatozoa/μl and mean sperm viability 66 ± 16%. Semen samples contained on average 20.5% morphologically normal spermatozoa and sperm malformations were detected mainly in the head (x¯ = 47.6%) and the tail regions (x¯ = 27.7%). Interestingly round bodies were detected in the ejaculates with a mean ratio of 0.6 round bodies per sperm. Semen analysis proved to be very useful to identify males with poor semen quality. Artificial insemination was performed 46 times in 9 females with either individual or pooled semen samples and 13 eggs from 7 females were laid afterwards. In 3 eggs, embryonic development was detected and 1 chick hatched successfully. Paternity testing confirmed the fatherhood of a one-winged semen donor male, a bird which was not able to copulate naturally. The results are very promising and underline that assisted reproduction techniques are a suitable tool for species conservation in captive breeding programs for psittacines.

The breeding management affects fresh and cryopreserved semen characteristics in Melopsittacus undulatus

Melopsittacus undulatus is a companion parrot worldwide diffused. Many parrots are considered endangered or vulnerable. The preservation of semen is crucial in endangered species, thus, M. undulatus could be a good model to study sperm characteristics and semen cryopreservation in these other endangered parrots. In this study the effect of the breeding management (males bred in promiscuous aviary or in couple) on sperm characteristics (motility, membrane integrity and morphometry) of fresh and cryopreserved semen was evaluated. The computer-assisted sperm analysis (CASA) revealed a significant effect of the husbandry method on semen characteristics in budgerigars: male housed in couple with the female in individual cages allowed the higher results in term of both semen quantity and sperm quality. Total and progressive motility were significantly higher in males bred in couple (68.7±8.9% and 54±15.9%, respectively) than in promiscuous aviary (48.3±15.1% and 24.4±12.4%, respectively), such as sperm velocity (average path velocity, straight line velocity, and curvilinear velocity). The type of sperm movement (amplitude of lateral head displacement, beat cross frequency, straightness, and linearity), sperm membrane integrity and morphometry parameters seemed not affected by the husbandry method. The standardization of a CASA procedure for the semen analysis in M. undulatus allow further studies on parrot semen manipulation and cryopreservation, but the method used for the breeding of the male could have a significant effect on the semen quality.