Functional Aspects of Seminal Plasma in Bird Reproduction

Collection, Handling, and Preservation of Wild Bird Semen: Current Status, Challenges, and Perspectives

Semen preservation is a significant biotechnology used to safeguard the genetic material of birds, especially those with declining populations, through biobanking. However, there are limited reports on the successful chilling or cryopreservation of wild bird semen. In general, these techniques are not yet well-established for several species of wild birds and pose several challenges such as the need for bird handling and training, contamination of semen samples, low volume of semen collected, and inefficient preservation protocols. To address these challenges and improve post-thawing outcomes, new possibilities are being investigated, including alternative collection methods to traditional digital massage, the use of antioxidants and enzymes in the medium for chilling or freezing, storage methods using different straws from the usual pellet, and slower freezing rates. This review aims to discuss the various aspects of applying semen preservation in wild birds to create germplasm banks, highlighting the primary results obtained and the challenges that need to be addressed.

Supplementation of Freezing Medium with Ginseng Improves Rooster Sperm Quality and Fertility Relative to Free Radicals and Antioxidant Enzymes

To the best of our knowledge, this study is the first to determine the effect of ginseng as an antioxidant supplement in freezing extenders on the quality of cryopreserved rooster semen. Semen samples were collected from 40 Thai native roosters (Pradu Hang Dum) using the dorso-abdominal massage method and then pooled and divided into five groups according to the concentrations of ginseng supplementation (0, 0.25, 0.50, 0.75, and 1 mg/mL) in a freezing extender. The semen suspensions were loaded into a medium straw and cryopreserved using the liquid nitrogen vapor method. The post-thaw semen was evaluated for sperm quality (sperm motility and membrane integrity), seminal plasma characteristics (lipid peroxidation, superoxide dismutase [SOD], catalase [CAT], and glutathione peroxidase [GPx]), and fertility. The results showed that ginseng extract supplementation at 0.25 mg/mL yielded the highest total motility, progressive motility, and membrane integrity (59.47%, 30.82%, and 48.30%, respectively; p < 0.05) in cryopreserved rooster semen. Higher malondialdehyde concentrations were observed in the control group than in the other groups (p < 0.05). SOD, CAT, and GPx increased compared with those in the control group (p < 0.05). The results showed that the fertility rate with 0.25 mg/mL of ginseng was higher than that of the control group (62.80% vs. 46.28%: p < 0.05). In conclusion, supplementation with 0.25 mg/mL of ginseng is recommended as an alternative component to the freezing extender to improve rooster semen cryopreservation.

Octopamine-MAPK-SKN-1 signaling suppresses mating-induced oxidative stress in Caenorhabditis elegans gonads to protect fertility

Sexual conflict over mating is costly to female physiology. Caenorhabditis elegans hermaphrodites generally produce self-progeny, but they can produce cross-progeny upon successfully mating with a male. We have uncovered that C. elegans hermaphrodites experience sexual conflict over mating, resulting in severe costs in terms of their fertility and longevity. We show that reactive oxygen species (ROS) accumulate on the apical surfaces of spermathecal bag cells after successful mating and induce cell damage, leading to ovulation defects and fertility suppression. To counteract these negative impacts, C. elegans hermaphrodites deploy the octopamine (OA) regulatory pathway to enhance glutathione (GSH) biosynthesis and protect spermathecae from mating-induced ROS. We show that the SER-3 receptor and mitogen-activated protein kinase (MAPK) KGB-1 cascade transduce the OA signal to transcription factor SKN-1/Nrf2 in the spermatheca to upregulate GSH biosynthesis.

Influence of Semen Collection Frequency and Seasonal Variations on Fresh and Frozen Semen Quality in Thai Native Roosters

This study aimed to determine the effects of the frequency of semen collection (once, twice, and thrice weekly) and seasonal variations on the fresh and frozen semen quality of Thai native roosters throughout the year. Data on temperature and humidity were collected and used to calculate the temperature-humidity index (THI). The average temperature and THI were lower in the winter than in the rainy season and the summer (p < 0.05). In contrast, the average relative humidity was not different among the seasons but was higher in the rainy season (p > 0.05). None of the fresh or frozen semen quality parameters were influenced by the frequency of semen collection, but the season did have an effect. The highest sperm concentration was obtained in the winter (p < 0.05). In contrast, the lowest sperm concentration was found during the rainy season, which presented the highest humidity. Regarding the frozen semen quality, the highest malondialdehyde concentration and the lowest motility were found in the summer (p < 0.05). In conclusion, semen collection can be conducted thrice per week for a consecutive year without affecting semen quality while maximizing sperm production. However, the highest sperm production was obtained in the winter, which is also a suitable season for producing semen for cryopreservation.

Does Antioxidant Mitoquinone (MitoQ) Ameliorate Oxidative Stress in Frozen-Thawed Rooster Sperm?

In this study, we aimed to determine the benefit of mitoquinone (MitoQ) in rooster semen extenders on sperm quality, motility parameters, antioxidant capacities, and apoptotic changes in post-thawed rooster semen. A total of 85 ejaculates from 18 roosters were collected and then divided into five equal aliquots and cryopreserved in extenders with 1.0% soy lecithin nanoparticles that contained various concentrations of MitoQ (0 nM (M0), 50 nM (M50), 100 nM (M100), 150 nM (M150), and 200 nM (M200)). By using a computer-assisted semen analyzer, sperm motility parameters were assessed after freeze thawing. The M150 group had significantly higher percentages of total motility, progressive motility, viability, acrosome membrane integrity, and mitochondrial activity than the other groups (p < 0.05). Compared to other groups, M100 and M150 groups produced a higher percentage of plasma membrane integrity and ATP contents (p < 0.05). Additionally, the lowest levels of ROS and MDA in spermatozoa were observed in M150 group (p < 0.05), whereas the highest levels of ROS and MDA were observed in sperm in the controls or the M200 group (p < 0.05). Significantly higher values of SOD, GPx, and Cas-3 were found in the M150 group compared to other groups (p < 0.05). Overall, these results demonstrate that MitoQ at 150 nM not only ameliorates post-thawed sperm quality and motility parameters by restoring ATP levels and preventing membrane damage, but also improves redox balance and antiapoptotic activities.

Comparative Transcriptome Analysis Provided a New Insight into the Molecular Mechanisms of Epididymis Regulating Semen Volume in Drakes

Semen volume is an important factor in artificial insemination (AI) of ducks. In drakes, seminal plasma that is produced by the epididymis determines the semen volume. However, the mechanism of epididymis regulating semen volume of drakes remains unclear. Therefore, the aim of the present study was to preliminarily reveal the mechanism regulating the semen volume through comparing the epididymal histomorphology and mRNA expression profiles between drakes with high-volume semen (HVS) and low-volume semen (LVS). Phenotypically, drakes in the HVS group produced more sperm than drakes in the LVS group. In addition, compared with the HVS group, the ductal square of ductuli conjugentes (DC) and dutus epididymidis (DE) in epididymis was significantly smaller in the LVS group, and the lumenal diameter and epithelial thickness of DC/DE were significantly shorter in the LVS group. In transcriptional regulation, 72 different expression genes (DEGs) were identified from the epididymis between HVS and LVS groups. Gene Ontology (GO) analysis indicated that the DEGs were mainly related to hormone secretion, neurotransmitter synthesis/transport, transmembrane signal transduction, transmembrane transporter activity, and nervous system development (p < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis showed that the DEGs were significantly enriched in pathways associated with hormone and neurotransmitter transmission (p < 0.05). In addition, further analysis of the top five pathways enriched by KEGG, nine key candidate genes (including SLC18A2, SNAP25, CACNA1B, GABRG2, DRD3, CAMK2A, NR5A1, and STAR) were identified, which could play a crucial role in the formation of semen. These data provide new insights into the molecular mechanism regulating semen volume of drakes and make feasible the breeding of drakes by semen volume.

A comparative proteomic study of high and low semen quality seminal plasma in drakes

Semen quality is the most important indicator in evaluating drake fecundity. At present, the low semen quality has become a major factor restricting the development of artificial insemination (AI) technology in ducks. Numerous studies have indicated that seminal plasma proteins play a crucial role in semen quality, but the mechanism of seminal plasma proteins regulating semen quality of drakes remains unclear. Thus, the objective of this study was to identify seminal plasma proteins associated with semen quality by comparing the seminal plasma proteomic profile of drakes with high-quality semen (HQS) and low-quality semen (LQS). Using a label-free MS-based method, a total of 745 seminal plasma proteins were identified. Of these, 55 differentially expressed proteins (DEPs) were identified (40 up-regulated and 15 down-regulated). Gene Ontology (GO) analysis showed that the DEPs were mainly enriched in transmembrane transport, extracellular matrix structural constituent, transferase activity, transferring acyl groups other than amino-acyl groups, transmembrane transporter activity, and integral component of membrane (P < 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analysis indicated that the DEPs were significantly enriched in apoptosis, tyrosine metabolism, glycerophospholipid metabolism, and sulfur metabolism pathways (P < 0.05). Moreover, through protein-protein interaction (PPI) network analysis, eight potential candidate proteins were identified, including P19140 (Alpha-enolase), R0KUV7 (Calreticulin), R0K3X3 (Solute carrier family 2, facilitated glucose transporter member 5), R0L6V0 (Proteasome subunit beta), R0JKW0 (Cytochrome c), R0JMC5 (Tubulin alpha chain), R0LCK1 (Cathepsin C), and R0JUP6 (Cathepsin D), which could play crucial roles in semen quality. Notably, further analysis demonstrated that key protein P19140 (Alpha-enolase) might can control the semen quality of drakes by regulating the expression of proteins related to apoptosis pathway. This study is the first systematically comparing the seminal plasma proteome of drakes exhibiting high and low semen quality. These results provide novel insights into the mechanisms regulating semen quality of drakes.

Transit along the vas deferens results in a high percentage of filiform spermatozoa with compacted chromatin in the rooster (Gallus domesticus)

The present work aimed to evaluate the chromatin compaction of rooster spermatozoa along the male reproductive tract, and to study the vas deferens lining cells, potentially involved in sperm maturation. Chromomycin A3 (CMA3) was used to determine the chromatin compaction of spermatozoa from testis (T), proximal (including epididymis, V1), intermediate (V2) and distal (V3) vas deferens, and ejaculate (E). Six Birchen Leonesa roosters were used. E was obtained in vivo by dorso-ventral massage. V1, V2 and V3 sperm were obtained post mortem (six pairs of vasa deferentia), by flushing. T was obtained by washing the testes, cut in halves. The fixed cells were stained with CMA3 and propidium iodide for flow cytometry assessment. Results showed higher (P P P.

The Effect of Semen Cryopreservation Process on Metabolomic Profiles of Turkey Sperm as Assessed by NMR Analysis

Semen cryopreservation represents the main tool for preservation of biodiversity; however, in avian species, the freezing−thawing process results in a sharp reduction in sperm quality and consequently fertility. Thus, to gain a first insight into the molecular basis of the cryopreservation of turkey sperm, the NMR-assessed metabolite profiles of fresh and frozen−thawed samples were herein investigated and compared with sperm qualitative parameters. Cryopreservation decreased the sperm viability, mobility, and osmotic tolerance of frozen−thawed samples. This decrease in sperm quality was associated with the variation in the levels of some metabolites in both aqueous and lipid sperm extracts, as investigated by NMR analysis. Higher amounts of the amino acids Ala, Ile, Leu, Phe, Tyr, and Val were found in fresh than in frozen−thawed sperm; on the contrary, Gly content increased after cryopreservation. A positive correlation (p < 0.01) between the amino acid levels and all qualitative parameters was found, except in the case of Gly, the levels of which were negatively correlated (p < 0.01) with sperm quality. Other water-soluble compounds, namely formate, lactate, AMP, creatine, and carnitine, turned out to be present at higher concentrations in fresh sperm, whereas cryopreserved samples showed increased levels of citrate and acetyl-carnitine. Frozen−thawed sperm also showed decreases in cholesterol and polyunsaturated fatty acids, whereas saturated fatty acids were found to be higher in cryopreserved than in fresh sperm. Interestingly, lactate, carnitine (p < 0.01), AMP, creatine, cholesterol, and phosphatidylcholine (p < 0.05) levels were positively correlated with all sperm quality parameters, whereas citrate (p < 0.01), fumarate, acetyl-carnitine, and saturated fatty acids (p < 0.05) showed negative correlations. A detailed discussion aimed at explaining these correlations in the sperm cell context is provided, returning a clearer scenario of metabolic changes occurring in turkey sperm cryopreservation.

Dietary supplementation with canthaxanthin and 25-hydroxycholecalciferol on the incubation performance and fertility of European quail breeders

This study assessed the effects of combined supplementation with canthaxanthin (Cx) and 25-hydroxycholecalciferol (25-OH-D₃) on incubation performance, fertility, and chick quality in European quail breeders. A total of 240 birds were distributed in a completely randomized design with 5 diets and 8 replicates. The animals were fed a basal diet containing 50 µg of vitamin D₃ or the basal diet supplemented with 3 ppm Cx and 34.5 µg 25-OH-D₃, 6 ppm Cx, and 69 µg 25-OH-D₃, 9 ppm Cx and 103.5 µg 25-OH-D₃, or 12 ppm Cx and 138 µg 25-OH-D₃. Incubation performance was analyzed in 2 periods (32 and 38 wk). Breeders aged 32 wk produced eggs with higher hatchability (P = 0.024), hatchability of fertile eggs (P = 0.026) and lower initial plus mid embryonic mortality (P = 0.021), whereas 38-week-old breeders generated chicks with a higher length at hatching (P < 0.001) and lower final plus pipped embryonic mortality (P = 0.021). In both age groups, Cx + 25-OH-D₃ levels had a quadratic effect on egg fertility (P < 0.001), hatchability of total (P < 0.001), and fertile eggs (P < 0.001). The fertility and the number of sperm cells in the perivitelline membrane was analyzed in two periods (26 and 40 wk). A quadratic effect of diet and days after mating on both parameters (P < 0.05) was observed. Eggs from supplementing breeders showed a high fertility (P < 0.001) and sperm cell counts (P < 0.001) for up to 7 and 3 d after mating, respectively, then the control group. Moreover, the supplementation of quail breeder diets with 6 ppm Cx + 69 µg 25-OH-D₃ enhances sperm cell longevity in sperm storage tubules, hatchability of total and fertile eggs, fertility, and chick quality, especially in older quail's breeders and reduces embryonic mortality.

Animal board invited review: Germplasm technologies for use with poultry

Over the last century, several reproductive biotechnologies beyond the artificial incubation of eggs were developed to improve poultry breeding stocks and conserve their genetic diversity. These include artificial insemination (AI), semen storage, diploid primordial germ cell (PGC) methodologies, and gonad tissue storage and transplantation. Currently, AI is widely used for selection purposes in the poultry industry, in the breeding of turkeys and guinea fowl, and to solve fertility problems in duck interspecies crosses for the production of mule ducklings. The decline in some wild game species has also raised interest in reproductive technologies as a means of increasing the production of fertile eggs, and ultimately the number of birds that can be raised. AI requires viable sperm to be preserved in vitro for either short (fresh) or longer periods (chilling or freezing). Since spermatozoa are the most easily accessed sex cells, they are the cell type most commonly preserved by genetic resource banks. However, the cryopreservation of sperm only preserves half of the genome, and it cannot preserve the W chromosome. For avian species, the problem of preserving oocytes and zygotes may be solved via the cryopreservation and transplantation of PGCs and gonad tissue. The present review describes all these procedures and discusses how combining these different technologies allows poultry populations to be conserved and even rapidly reconstituted.

Effect of vitamin E supplementation on chicken sperm quality: A meta-analysis

Background and Aim:

Among several factors, the sperm quality of poultry is affected by the rooster’s body size and the availability of antioxidants like vitamin E. This study aimed to determine the effect of dietary vitamin E supplementation on rooster sperm quality through a meta-analysis.

Materials and Methods:

After verification and evaluation, a total of 19 articles were included in this study. Data, including dietary vitamin E, semen volume, concentration, total sperm cells, pH, motility, viability, percentage of dead and abnormal sperm, vitamin E sperm content, malondialdehyde (MDA) content, and testosterone levels, were tabulated in a database; these were subsequently analyzed using mixed modeling with vitamin E dose as a fixed effect and study identity as a random effect.

Results:

Dietary supplementation level of vitamin E significantly (p<0.001) affected sperm concentration, significantly affected motility (p<0.001), significantly affected sperm vitamin E (p<0.001), significantly affected viability (p<0.001), and significantly affected chicken sperm fertility (p=0.001). Vitamin E administration also significantly reduced the number of sperm cell deaths (p<0.001); however, increased dietary levels of vitamin E did not affect semen volume (p=0.853), pH (p=0.951), MDA (p=0.542), the percentage of abnormal sperm cells (p=0.343), nor testosterone levels (p=0.063).

Conclusion:

Dietary vitamin E supplementation is recommended for male chickens since it generally enhances the quality of their sperm.

Chronic Dietary Exposure of Roosters to a Glyphosate-Based Herbicide Increases Seminal Plasma Glyphosate and AMPA Concentrations, Alters Sperm Parameters, and Induces Metabolic Disorders in the Progeny

The effects of chronic dietary Roundup (RU) exposure on rooster sperm parameters, fertility, and offspring are unknown. We investigated the effects of chronic RU dietary exposure (46.8 mg kg⁻¹ day⁻¹ glyphosate) for 5 weeks in 32-week-old roosters (n = 5 RU-exposed and n = 5 control (CT)). Although the concentrations of glyphosate and its main metabolite AMPA (aminomethylphosphonic acid) increased in blood plasma and seminal fluid during exposure, no significant differences in testis weight and sperm concentrations were observed between RU and CT roosters. However, sperm motility was significantly reduced, associated with decreased calcium and ATP concentrations in RU spermatozoa. Plasma testosterone and oestradiol concentrations increased in RU roosters. These negative effects ceased 14 days after RU removal from the diet. Epigenetic analysis showed a global DNA hypomethylation in RU roosters. After artificial insemination of hens (n = 40) with sperm from CT or RU roosters, eggs were collected and artificially incubated. Embryo viability did not differ, but chicks from RU roosters (n = 118) had a higher food consumption, body weight and subcutaneous adipose tissue content. Chronic dietary RU exposure in roosters reduces sperm motility and increases plasma testosterone levels, growth performance, and fattening in offspring.

Recent Progress in Spermatology Contributing to the Knowledge and Conservation of Rare and Endangered Species

There is a remarkable diversity in the animal kingdom regarding mechanisms underlying the production, maturation, structure, and function of sperm cells. Spermatology studies contribute to the knowledge of species diversity and also provide information about individual or population fitness. Furthermore, this fundamental research is required before collected spermatozoa can be used for conservation breeding, including assisted reproduction and cryobanking. This article aims to (a) review the most recent knowledge on sperm morphology and function in wild animal species, (b) analyze how this knowledge can be used to save species in their natural habitat or ex situ, and (c) propose future scientific directions in wildlife spermatology that could positively impact animal conservation. Variations in sperm structure and performance within and between species have multiple origins and significance. This collective body of knowledge enables the design and implementation of conservation strategies and action plans that integrate several disciplines. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

From the Semen Collection Method to the Hatchlings: The Use of Cryopreserved Sperm from Pheasants Fed an Antioxidant-Enriched Diet

A widely used approach to preserving genetic diversity in birds involves the cryopreservation of semen. In this process, cells are subjected to physical and chemical stresses, but not all cell species respond equally. Many studies have been published on the freezing-thawing of sperm cells from a wide variety of domestic and wild species, on issues ranging from the sperm quality to different protocols, fertilisation success rates, etc. Nevertheless, very little information is available on the common pheasant. To fill this gap, the aim of this study was to describe the pheasant semen collection method, evaluate some qualitative parameters of sperm from males fed an antioxidant-enriched diet, and to test the in vivo fertilising capacity of the cryo-preserved semen. The freezing protocol employed involved pellets thawed by the hotplate method. Dimethylacetamide was used as a cryoprotectant at a final concentration of 6%. A total of six AIs were performed at 3-4-day intervals on a total of 40 females with doses of 35 × 106 of normal live thawed sperm. Males receiving the enriched diet produce more abundant and concentrated ejaculates. Freeze-thawed sperm lost 85% of their initial mobility, and diet influenced neither sperm mobility nor viability. The enriched diet did improve the number of normal freeze-thawed cells and was associated with a lower sperm fracture incidence. Regardless of the dietary group, frozen-thawed sperm resulted in a fertility rate of 30%, with 8-9 chicks hatching for every 100 eggs incubated.

Optimization of a Protocol for the Cryopreservation of Sperm in Pellets for the Common Pheasant (Phasianus colchicus mongolicus)

The sperm of each avian species and breed have unique characteristics that render them more or less susceptible to the freezing-thawing process; therefore, a suitable cryopreservation protocol that is specific for the sperm of each type of bird is needed. In this context, little information about the common pheasant's sperm is available. Therefore, the aim of this study was to test different parameters at each step of the process of freezing into pellets and thawing to detect the least deleterious parameter settings. Sixteen different protocols were tested by studying two levels in each of the four steps (dilution, equilibration at 5 °C, final dimethylacetamide concentration, and dimethylacetamide equilibration time) comprising the freezing process. The pheasant sperm exhibited a high susceptibility to the damage caused by freezing into pellets; however, the survival of the sperm reached 29%, and the greatest recovered mobility was 22%. The mobility of the sperm was affected by the dilution and the dimethylacetamide concentration, and the viability of the sperm was affected by the equilibration at 5 °C and the dimethylacetamide equilibration. The protocols that caused the least damage to the pheasant sperm were found to be those with higher dilution rates, 10 min of equilibration at 5 °C, and 6% dimethylacetamide equilibrated for 1 or 5 min. In the present study, we individualise some applicable parameters for certain critical steps of the freezing-thawing process; however, further investigations are needed in order to improve upon and complete a suitable protocol for the cryopreservation and thawing of pheasant sperm.

Research Note: Evaluation of two methods for adding cryoprotectant to semen and effects of bovine serum albumin on quality characteristics of cryopreserved rooster spermatozoa

Chicken semen cryopreservation is a tool for programs of genetic diversity management and endangered breeds conservation. Due to physiological features, the fertility rates of cryopreserved poultry sperm are lower than mammal species. Thus, improvement of the semen cryopreservation methods is required. A first study was performed by a 2 × 2 factorial design consisting of 2 methods of adding the cryoprotectant [Direct or Diluted (mixed with extender medium)] and 2 cryoprotectants (glycerol and dimethylacetamide). Then sperm quality indicators were evaluated after freezing. A second study with a 2 × 2 design was conducted to evaluate the effectiveness of bovine serum albumin (BSA) on the optimization of 2 different extenders (Lake and Animal Sciences Group [ASG]). Viability and motility variables were evaluated before and after freezing. There was no significant difference in sperm viability and motility variables between Direct or Diluted methods. Supplementation of extenders with BSA improved most of the sperm motility variables in both extenders before and after freezing. Progressive sperm, non-progressive sperm before freezing, and all post-thaw sperm motility parameters, except amplitude of lateral head displacement and beat-cross frequency, were increased in BSA-supplemented extenders (P < 0.05), and BSA improved sperm viability in ASG extender after thawing (P < 0.05). After thawing, the interaction between extender and BSA (P < 0.05), eliminated the differences between the 2 BSA-supplemented media in curvilinear velocity, straight-line velocity, average path velocity, and amplitude of lateral head displacement which were higher in non-supplemented ASG extender than nonsupplemented Lake medium. In conclusion, the direct or diluted methods of adding glycerol or dimethylacetamide, did not significantly affect the post-thaw sperm characteristics. BSA positively affected most of the post-thaw sperm motility indicators regardless of the type of extender and resulted in significantly higher post-thaw sperm viability in ASG medium.

Sperm Cryopreservation in American Flamingo (Phoenicopterus Ruber): Influence of Cryoprotectants and Seminal Plasma Removal

The American flamingo is a useful model for the development of successful semen cryopreservation procedures to be applied to threatened related species from the family Phoenicopteridae, and to permit genetic material banking. Current study sought to develop effective sperm cryopreservation protocols through examining the influences of two permeating cryoprotectants and the seminal plasma removal. During two consecutive years (April), semen samples were collected and frozen from American flamingos. In the first year, the effect of two permeating cryoprotectants, DMA (dimethylacetamide) (6%) or Me2SO (dimethylsulphoxide) (8%), on frozen-thawed sperm variables were compared in 21 males. No differences were seen between DMA and Me2SO for sperm motility, sperm viability, and DNA fragmentation after thawing. In the second year, the role of seminal plasma on sperm cryoresistance was investigated in 31 flamingos. Sperm samples were cryopreserved with and without seminal plasma, using Me2SO (8%) as a cryoprotectant. The results showed that samples with seminal plasma had higher values than samples without seminal plasma for the following sperm variables: Straight line velocity (22.40 µm/s vs. 16.64 µm/s), wobble (75.83% vs. 69.40%), (p < 0.05), linearity (62.73% vs. 52.01%) and straightness (82.38% vs. 73.79%) (p < 0.01); but acrosome integrity was lower (55.56% vs. 66.88%) (p < 0.05). The cryoresistance ratio (CR) was greater in samples frozen with seminal plasma than without seminal plasma for CR-progressive motility (138.72 vs. 54.59), CR-curvilinear velocity (105.98 vs. 89.32), CR-straight line velocity (152.77 vs. 112.58), CR-average path velocity (122.48 vs. 98.12), CR-wobble (111.75 vs. 102.04) (p < 0.05), CR-linearity (139.41 vs. 113.18), and CR-straightness (124.02 vs. 109.97) (p < 0.01). This research demonstrated that there were not differences between Me2SO and DMA to successful freezing sperm of flamingos; seminal plasma removal did not provide a benefit for sperm cryopreservation.