Changes in turkey semen lipids during liquid in vitro storage

Liquid semen storage-induced alteration in the protein composition of turkey (Meleagris gallopavo) spermatozoa

Liquid storage of turkey semen without the loss of fertilizing ability is of practical interest to the poultry industry. However, fertility rates from liquid-stored turkey semen decline within a few hours. A clear cause of the decline in spermatozoa quality remains unidentified. Therefore, the purpose of the present study was to monitor the dynamics of proteomic changes in spermatozoa during 48 h of liquid storage by 2-dimensional difference in-gel electrophoresis coupled with matrix-assisted laser desorption/ionization mass spectrometry. A total of 57 protein spots were differentially expressed between fresh and stored spermatozoa; 42 spots were more and 15 were less abundant after 48 h of semen storage. Raw proteomic data are available via ProteomeXchange with identifier PXD043050. The selected differentially expressed proteins (DEPs) were validated by western blotting and localized in specific spermatozoa structures by immunofluorescence, such as the head (acrosin and tubulin α), midpiece (acrosin, aconitate hydratase 2, and glycerol-3-phosphate dehydrogenase) and tail (tubulin α). Most of the DEPs that changed in response to liquid storage were related to flagellum-dependent cell motility, energy derivation through oxidation of organic compounds and induction of fertilization, suggesting the complexity of the processes leading to the decrease in stored semen quality. The damaging effect of liquid storage on spermatozoa flagellum manifested as more microtubule proteins, such as tubulins and tektins, most likely formed by posttranslational modifications, tubulin α relocation from the tail to the sperm head, which appeared after 48 h of semen storage, and decreases in fibrous shelf proteins at the same time. Motility could be affected by dysregulation of Ca2+-binding proteins and disturbances in energy metabolism in spermatozoa flagellum. Regarding sperm mitochondria, DEPs involved in energy derivation through the oxidation of organic compounds indicated disturbances in fatty acid beta oxidation and the tricarboxylic acid cycle as possible reasons for energy deficiency during liquid storage. Disturbances in acrosin and 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase zeta may be involved in rapid declines in the fertility potential of stored turkey spermatozoa. These results showed the complexity of the processes leading to a decrease in stored semen quality and broadened knowledge of the detrimental effects of liquid storage on turkey spermatozoa physiology.

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.

Transcriptome analysis of inseminated sperm storage tubules throughout the duration of fertility in the domestic turkey, Meleagris gallopavo

Sperm storage tubules (SST) are specialized invaginations of the oviductal epithelium that permit avian species to store spermatozoa for extended periods of time, without compromising sperm fertilization capacity. The molecular and physiological mechanisms behind sperm storage tubule differentiation, sperm protection, and regression remain largely unknown, but most likely have potential implications for substantially improving hen fertility, sperm storage, and semen cryopreservation in commercial poultry species. RNA sequencing was performed on sperm storage tubules isolated from the epithelium of the uterovaginal junction (UVJ) from hens at d 1, 7, 30, 60, and 90 postinsemination (n = 4 per timepoint). Read mapping and differential expression analysis were performed using CLC Genomics Workbench. A total of 2,340 differentially expressed genes were subjected to pathway analysis through Ingenuity Pathway Analysis (IPA). Through functional annotation of differentially expressed genes during early, peak, and late egg production, novel insights regarding the role of innate and acquired immune response to sperm, lipid synthesis and transfer, steroid hormone signalling, cytoskeletal reorganization, and regulation of ion homeostasis in SST were obtained. Additionally, potential pathways were identified that could be involved with suppressing sperm motility while sperm reside within the SST. Upstream analysis identified potential regulatory roles for 18 upstream regulators that could modulate sperm storage tubule function, including suppression of sperm motility. Understanding sperm storage tubule function throughout the laying cycle, especially with regards to sperm preservation may allow for the development of industry-based protocols for semen storage and cryopreservation that mimic the sperm preservation capabilities of SST and improve fertility.

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.

Spermatozoa Survival in Egg Yolk-Based and Soybean-Based Extenders at Ambient and Chilling Temperature in Domestic Turkeys (Meleagris gallopavo)

Populations of many galliform species have declined mainly due to habitat loss and over-hunting, notably the Congo peacock, which has been classified as a vulnerable species by the International Union for Conservation of Nature (IUCN). The domestic turkey, being a species of least concern, which has been reported to be closely related to peacocks, could serve as a model for the optimization of assisted reproductive technologies for the Congo peacock. This study was aimed at developing a suitable turkey semen extender for artificial insemination in field conditions. Semen was collected using the dorso-abdominal massage technique from seven turkey toms and analyzed. Ejaculates with >70% motility and >80% live spermatozoa were pooled and divided into four aliquots (four treatments). Each of the four treatments was extended in a soybean-based extender or an egg yolk-based extender, with or without L-ascorbic acid. Two liquid preservation protocols (ambient temperature (35 °C) and chilled (4 °C)) were employed, and quality parameters including motility, viability and morphology were evaluated. The results show that the two extenders were similar with regard to semen quality parameters, and L-ascorbic acid supplementation of the turkey semen extenders improved semen quality during liquid storage.

Assessing different liquid-storage temperatures for rooster spermatozoa

Although liquid-storage is extensively used in poultry, there are still questions on how sperm physiology is affected and to what extent sperm functions are disrupted by storage temperature and time. There, therefore, was investigation of storage temperature and durations on multiple semen variables. The storage at 37 °C was the most damaging, affecting values for several variables within 4 h of storage, whereas most differences occurred between 5 and 25 °C after 8 h. Progressive motility and mitochondrial function started to decrease within 2 h at 25 and 37 °C, and within 4 h at 5 °C. Acrosomal damage only occurred in samples at 37 °C. Eosin-negrosin staining indicated there was damage to the plasma membrane at 37 °C, however, with use of propidium iodide there were differences between 5 and 25 °C following 24 h. Temperatures of 5 and 25 °C resulted in similar curves for chromatin dispersion although chromatin integrities differed with storage for periods longer than 4 h. At 37 °C, results using both chromatin evaluations indicated there was damage after 2 h of incubation. Oxidative stress at 5 and 25 °C was similar when there was 24 h of storage. Intriguingly, there were no interaction between temperature and storage duration for peroxidized sperm membrane and total peroxidation status. These findings indicated that with a prolonged storage at 5 °C there were not marked changes in chicken spermatozoa, whereas at 25 °C there did not appear to be sperm damage occurring as a result of short-term storage.

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.

Viability of in vitro preserved sperm of Harris's hawk (Parabuteo unicinctus)

Harris hawks (Parabuteo unicinctus) are the raptors with more anthropogenic use, which makes it necessary to improve their reproduction either natural or assisted for sustainable use even though they are not endangered. The aim of this study was to determine fresh and thawed P. unicinctus sperm capacitation and acrosome reaction parameters as indicators of sperm viability in ejaculates of birds with injuries. A total of 30 ejaculates were analyzed as fresh and thawed samples. Basic sperm evaluations as well as in vitro acrosomal reaction capability through the presence and distribution of Ca²⁺ and N-acetylglucosamine and sialic acid using chlortetracycline and agglutinin-fluorescein isothiocyanate Triticum vulgaris were performed, respectively. Tagged samples were observed using epifluorescence microscopy. The results indicated 30.00% decrease in sperm viability following freeze-thaw, while rate of capacitated sperms (10.00%) and the percentage of sperm with acrosomal reaction (40.00%) were increased. The results of the experiment demonstrated that the post-thaw viability of the obtained sperm may be an alternative for use in artificial insemination.

Functional Aspects of Seminal Plasma in Bird Reproduction

This review provides an updated overview of the seminal plasma composition, and the role of metabolic and protein components on the sperm function of avian species. In addition, the implication of seminal plasma on assisted reproductive techniques of birds was discussed. The semen of birds usually has exceptionally high sperm concentration with relatively little seminal plasma, but this contributes to very fast changes in sperm metabolism and function. The biochemical characteristics and physiological roles of the various seminal plasma components in birds (carbohydrates, lipids, amino acids, hormones, and proteins) are poorly understood. Seminal plasma content of proteins has an action on most cellular functions: metabolism, immunity, oxido-reduction regulation, proteolysis, apoptosis, ion homeostasis, and antimicrobial defenses. The variable amount of many proteins is related to a different fertility capacity of poultry sperm. The role of seminal plasma on semen conservation (chilling and freezing) remains largely a matter of speculation, as both inhibitory and stimulating effects have been found. Whereas the presence of seminal plasma did not seem to affect the sperm survival after freezing-thawing, DNA fragmentation is lower in the absence of seminal plasma. The molecular basis of the influence of seminal plasma on sperm cryo-resistance was also discussed in the present review.

Mitochondrial membrane potential and reactive oxygen species in liquid stored and cryopreserved turkey (Meleagris gallopavo) spermatozoa

The extensive use of artificial insemination in turkeys has led to the development of in vitro semen storage. However, fertility rates from liquid stored and frozen/thawed turkey semen are still unsatisfactory. The aim of the study was to assess spermatozoa viability, mitochondrial membrane potential (MMP), and reactive oxygen species production (ROS) in liquid stored and cryopreserved turkey semen with the use of flow cytometry. Moreover, motility and adenosine triphosphate (ATP) content in sperm were monitored at the same time to link flow cytometry data with sperm movement and energetics. Liquid storage led to a decrease in sperm motility (80.6 vs. 55.6%, for fresh and stored for 48 h), live sperm with an intact MMP (59.9 vs. 30.5% for fresh and stored for 48 h), and a 20-fold decrease in ATP content after 24 h of storage. A 3-fold increase in ROS+ sperm was observed after 48 h of storage (9.3 vs. 26.8% for fresh and stored for 48 h). Semen equilibration before cryopreservation affected only ATP content. However, freezing/thawing led to a dramatic decrease in all of the studied semen quality parameters. A 5-fold decrease in live sperm with intact MMP (59.8 vs. 11.9%) and a 7-fold increase in sperm ROS+ (10.8 vs. 74.4%) were recorded between fresh and frozen/thawed semen. The results strongly suggested that a significant loss of MMP and a disturbance in sperm ATP production during semen storage can be the main reason for the decline in sperm motility. The disturbance of mitochondria activity during storage seems to be associated with the increase in oxidative stress in turkey semen. Turkey sperm mitochondria also appear to be very sensitive to cryodamage. Diminished energy production in turkey spermatozoa, visible as the low percentage of sperm with an intact MMP and low level of ATP after freezing/thawing, which is associated with high ROS generation, could be responsible for the low fertilizing ability of cryopreserved turkey semen.

Cryopreservation effects on sperm function and fertility in two threatened crane species

The capacity to cryopreserve semen from captive cranes facilitates production of offspring from behaviorally incompatible or geographically separated pairs, and allows for long-term preservation of valuable genetic materials. The present study sought to develop effective cryopreservation protocols for whooping (Grus americana) and white-naped (Grus vipio) cranes, through examining the influences of two permeating (DMA and Me₂SO) and one non-permeating (sucrose) cryoprotectants, as well as vitamin E on post-thaw sperm survival. In Study 1, ejaculates (whooping: n = 10, white-naped: n = 8) were collected and cryopreserved in one of six cryo-diluents (crane extender with: DMA; DMA+0.1M sucrose; Me₂SO; Me₂SO+0.1M sucrose; 0.1M sucrose; 0.2M sucrose) using a two-step cooling method. Frozen samples were thawed and assessed for overall motility, motion characteristics, membrane integrity, morphology, and ability to bind to the inner perivitelline membrane (IPVM). In Study 2, whooping crane ejaculates (n = 17) were frozen in crane extender containing Me₂SO alone or with vitamin E (5 μg/mL or 10 μg/mL). Frozen samples were thawed and assessed as in Study 1, except the binding assay. White-naped crane sperm were more tolerant to cryopreservation than whooping crane (15% vs 6% post-thawed motility). In both species, sperm cryopreserved in medium containing Me₂SO alone displayed higher post thaw survival and ability to bind to IPVM than the other cryodiluent treatments. Vitamin E supplementation exerted no benefits to post thaw motility or membrane integrity. The findings demonstrated that there was species specificity in the susceptibility to cryopreservation. Nevertheless, Me₂SO was a preferred cryoprotectant for sperm from both whooping and white-naped cranes.

Sperm subpopulations in avian species: a comparative study between the rooster (Gallus domesticus) and Guinea fowl (Numida meleagris)

The main aims of this research were to study possible differences in objective morphometric sperm characteristics, establish normative sperm morphometry standards, and evaluate the presumed different subpopulation distribution of avian spermatozoa from the rooster (Gallus domesticus) and Guinea fowl (Numida meleagris) as model avian species. Seventy-two ejaculates (36 per species studied) were obtained manually, following a training period involving gently combined dorso-abdominal and lumbo-sacral massage of the birds. Ejaculates were processed for volume, sperm concentration, viability, motility, and morphology. Moreover, samples were submitted for sperm morphometric assessment using objective Computer-Assisted Semen Analysis for Morphometry (CASA-Morph) methods, with sperm morphometric descriptors evaluated by Principal Component Analysis (PCA) and multivariate clustering analyses. There were several differences observed between the avian species in values obtained for ejaculate volume and sperm concentration (P < 0.001). Irrespective of species, PCA revealed two Principal Components (PCs) explaining more than 80% of the variance. In addition, the number of subpopulations differed with species (three and five subpopulations for rooster and Guinea fowl, respectively). Moreover, the distribution of the sperm subpopulations was found to be structurally different between species. In conclusion, our findings from using CASA-Morph methods indicate pronounced sperm morphometric variation between these two avian species. Because of the strong differences observed in morphometric parameter values and their subpopulation distribution, these results suggest that application of objective analytical methods such as CASA-Morph could substantially improve the reliability of comparative studies and help establish valid normative sperm morphological values for avian species.

Gel-coated tubes extend above-freezing storage of honey bee (Apis mellifera) semen to 439 days with production of fertilised offspring

Honey bees are an important agricultural species; however, relatively little work has been done to improve artificial reproductive technologies for this animal. The collection and distribution of germplasm for breeding and conservation is critical for improving managed honey bee populations and conserving threatened subspecies. The most efficient method of controlling breeding in honey bees is by artificial insemination. The collection of semen for insemination requires the use of antibiotics, which is especially critical if semen is to be stored for any length of time. The introduction of antibiotics is normally done through a balanced salt solution. In this study we compare, at two temperatures, the storage of undiluted semen in antibiotic–gel-coated capillary tubes with storage of semen diluted in a balanced salt solution containing antibiotics. Live–dead cell staining and artificial insemination of honey bee queens were performed at 45, 99 and 439 days after collection of the semen. In every case the antibiotic–gel-coated tube storage method at 14°C produced a higher percentage of fertilised offspring. This study demonstrates the longest period of time spermatozoa have been stored above freezing while maintaining fertilisation capacity.

Influence of Post-Mortem Sperm Recovery Method and Extender on Unstored and Refrigerated Rooster Sperm Variables

Many post-mortem sperm collection techniques have been described for mammalian species, but their use in birds is scarce. This paper compares the efficacy of two post-mortem sperm retrieval techniques - the flushing and float-out methods - in the collection of rooster sperm, in conjunction with the use of two extenders, i.e., L&R-84 medium and Lake 7.1 medium. To determine whether the protective effects of these extenders against refrigeration are different for post-mortem and ejaculated sperm, pooled ejaculated samples (procured via the massage technique) were also diluted in the above extenders. Post-mortem and ejaculated sperm variables were assessed immediately at room temperature (0 h), and after refrigeration at 5°C for 24 and 48 h. The flushing method retrieved more sperm than the float-out method (596.5 ± 75.4 million sperm vs 341.0 ± 87.6 million sperm; p < 0.05); indeed, the number retrieved by the former method was similar to that obtained by massage-induced ejaculation (630.3 ± 78.2 million sperm). For sperm collected by all methods, the L&R-84 medium provided an advantage in terms of sperm motility variables at 0 h. In the refrigerated sperm samples, however, the Lake 7.1 medium was associated with higher percentages of viable sperm, and had a greater protective effect (p < 0.05) with respect to most motility variables. In conclusion, the flushing method is recommended for collecting sperm from dead birds. If this sperm needs to be refrigerated at 5°C until analysis, Lake 7.1 medium is recommended as an extender.

The effect of bovine embryo culture without proteins supplements until day 4 on transcription level of hyaluronan synthases, receptors and mtDNA content

The effect of bovine embryo culture on a flat surface, (without a surface-active compound) on the level of mRNA expression of hyaluronan (HA) synthases (Has1, Has2 and Has3), Ha receptors RHAMM and C44 receptors was evaluated by mitochondrial DNA concentration and in vitro development. Cultures were evaluated up to 96 h post-insemination (hpi) using SOFaa medium. Of the three Has isoforms, Has2 expression only increased in the bovine serum albumin (BSA)-only supplemented groups regardless of time of BSA addition. Expression of RHAMM receptors was highly dependent on the addition of HA, irrespective of the presence of BSA in the medium. In contrast, expression of the CD44 receptor gene was not affected by any treatment. The cleavage rates and number of embryos that developed to <or=8-cell stage by day 4 were not affected by lack of BSA in the medium, but increased numbers of blastocysts developed in medium supplemented with BSA from days 1 or 4 with or without HA than in medium that had HA only. Addition of both HA and BSA at day 4 increased mtDNA copy numbers at the blastocyst stage. Data suggest that the addition of BSA and/or HA at 96 hpi increased expression of RHAMM and Has2 genes, but not CD44, Has1 or Has3 genes. Higher expression levels of Has2 than Has1 and the three isoforms indicate that high- rather than low-molecular-weight HA should be used for preimplantation bovine embryo culture.

INDIVIDUAL CRYOPRESERVATION WITH DIMETHYL SULFOXIDE AND POLYVINYLPYRROLIDONE OF EJACULATES AND POOLED SEMEN OF THREE AVIAN SPECIES

Artificial insemination (AI) has been used for avian reproduction due to the discovery of cryoprotectants extending its usefulness both in production of domestic fowl and conservation of wild species. The goal of this study was to assess the effect on domestic and wild fowl pooled semen and individual ejaculate cryopreservation with dimethyl sulfoxide (DMSO) and polyvinylpyrrolidone (PVP). Twenty ejaculates and twenty samples of pooled semen of roosters, pheasants and hawks were frozen in media containing DMSO or PVP. DMSO and PVP cryopreservation are equally effective both for ejaculates and pooled semen. Even PVP is a good alternative since no significant difference was found when compared to DMSO. The fertilizing capacity of fresh and cryopreserved pooled semen was analyzed through AI of hens and female pheasants. Similar fertility rates using DMSO, PVP or frozen-thawed samples demonstrated that reproduction is possible through the use of cryopreserved semen. In the case of female pheasants, the same values were obtained with both cryopreserved and fresh semen.

Relationships between sterol/phospholipid composition and xenobiotic transport in nematodes

Therapeutic failure limits prophylaxis of nematode diseases and has been mainly attributed to mutations in cellular targets of anthelmintics. Besides these specific mechanisms, alterations of drug transport also occur in parasites resistant to anthelmintics and depend on both the presence of membrane pumps such as P-glycoprotein (Pgp) and on the lipid composition of membranes. We recently showed in the nematode Haemonchus contortus, using eggs as a model, that the total cholesterol (TC) concentration alters the transport of lipophilic molecules due to membrane pumps such as P-glycoprotein and the resistance to anthelmintics. The effect of TC may depend on the presence of other lipids interacting with TC. Therefore, we analysed the lipid composition and its relationship with Pgp and resistance to anthelmintics. Better correlations were found between Pgp and free cholesterol (FC) than with TC. We also showed that the relationships between lipid composition and resistance to anthelmintics or Pgp depended on the equilibrium between FC and phospholipids (PLs), mainly PLs known to be present primarily in either the external leaflets of cell membranes or the internal leaflets. The PLs phosphatidylcholine and phosphatidylethanolamine played the most significant role, but phosphatidic acid also influenced drug resistance.

Effects of liquid storage on amidase activity, DNA fragmentation and motility of turkey spermatozoa

Short-term liquid storage of turkey semen is of great interest in the management of turkey reproduction due to the extensive use of artificial insemination. This study examined changes in DNA fragmentation (using a comet assay), sperm motility characteristics (using computer-aided sperm analysis), and amidase activity (using a colorimetric assay) of turkey sperm stored for 24 and 48 h. In addition we found that turkey spermatozoa contain besides acrosin, additional two serine proteinases of molecular weight of 34 and 42 kDa. We found that, after 48 h of liquid storage, decreases in sperm motility characteristics and increases in amidase activity and DNA fragmentation occurred. An increase of amidase activity was found after 24h. Decreases in sperm motility and increase in DNA fragmentation were found after 48 h of storage. These data suggest that a decrease in turkey sperm quality during short-term storage is related to disturbances to the acrosome, presumably related to premature activation of acrosomal serine proteinases, and to a lesser extent a decrease in sperm motility characteristics and damage of sperm DNA.

Effect of organic selenium on turkey semen quality during liquid storage

The aim of the present study was to evaluate the effect of dietary organic selenium on the turkey semen during storage. Twenty males (BUT, Big 6, 40 weeks of age) were divided into control (n=10) and experimental group (n=10). The turkeys in the both groups were fed with a commercial diet containing 0.1 ppm Se in the form of sodium selenite. The experimental birds were additionally supplied with 0.3 ppm organic Se in the form Sel-Plex (Alltech, Inc.). After 30 days of feeding, the semen samples were collected twice a week for the 3 weeks of the study and diluted 1+1(v/v) with TUR-2 diluent, and stored in a water bath (+10 to 15 degrees C) for 6 h. The percentage of motile spermatozoa, the sperm viability (live/dead spermatozoa), total lipids, phospholipids and total cholesterol were assessed in fresh and stored semen. The fertilizing ability of semen was assessed by artificial insemination of 30 hens per group with dose containing 200x10(6) spermatozoa weekly. After 6 h of semen storage, the motility of spermatozoa decreased significantly in the control group (by 8.7 relative percent, P<0.05) and only by four relative percent (P>0.05) in experimental group reflecting a protective effect of dietary Se supplementation. The proportion of live spermatozoa was higher in fresh semen and significantly lower in stored semen. The positive effect of Se supplementation was observed on the lipid composition of stored semen: the concentration of the total lipids and phospholipids in the seminal plasma from control group significantly increased, while in the experimental group remained constant. Better semen integrity in the experimental group was associated with an improved fertilizing ability of spermatozoa: the fertility rate of stored spermatozoa in the control group was 88%, while in the experimental group was 90.5%.

Combined effect of DHA and α-tocopherol enrichment on sperm quality and fertility in the turkey

The aim of the present study was to characterize the dietary effects of n-3 LC-PUFA and alpha-tocopheryl acetate (vE) on the quality, phospholipid fatty acid composition, alpha-tocopherol content (alpha-T) and in vitro susceptibility to lipid peroxidation in turkey semen. Fertility of fresh semen was also evaluated. Male turkeys were randomly divided and fed either a control diet or a fish oil and vE rich diet (FO diet) from 40 to 60 weeks of age. The FO diet increased the proportion of n-3 fatty acids in spermatozoa and as a consequence the (n-3)/(n-6) ratio also increased. These changes did not affect the proportion of n-9 PUFAs, particularly of C22:3n-9, in semen. The sperm content of alpha-T was dependent by the dietary supplementation of the vitamin and the sperm content was more than doubled supplying 120 mg kg(-1) of feed to the males compared to the 60 mg kg(-1) of feed in the control diet. In agreement with the major content of alpha-T in spermatozoa collected from the FO group were significantly less susceptible to in vitro induced oxidation. The reproductive capacity of the male breeders was not affected by the diet; however the result is considered of some relevance for field conditions where even very small changes have economic interest being applied to large bird population.

Update on semen technologies for animal breeding

Despite the scale of the livestock breeding industry, where many millions of insemination doses are prepared each year, sperm preparation techniques are used infrequently in animal assisted reproduction compared with its human counterpart. However, some of the techniques used for human sperm preparation, for example, density gradient centrifugation, improve the quality of sperm preparations which is, in turn, reflected by an increased conception rate. The preparation technique separates motile spermatozoa with normal morphology and intact DNA from the total sperm population, leaving behind immature or senescent spermatozoa, morphologically abnormal ones and those with damaged DNA. Furthermore, the motile spermatozoa are removed from the seminal plasma which carries cells, cellular debris and reactive oxygen species, as well as pathogens. Gradient-prepared spermatozoa survive longer, either in liquid storage or when cryopreserved, and are free of bacteria and viral infectivity if prepared carefully. Preparation techniques such as density gradient centrifugation, or the simplified single layer centrifugation technique, have considerable potential for aiding sperm preparation from poor quality semen samples, such as may be obtained from unselected semen donors in captive breeding programmes, or from performance horses. Moreover, the removal of pathogens has important implications, both for disease control and for avoiding the use of antibiotics in semen extenders, which can be detrimental to sperm survival.

Effect of Semen Extender and Density Gradient Centrifugation on the Motility and Fertility of Turkey Spermatozoa

In the absence of commercially viable methods for cryopreserving turkey spermatozoa, new processing methods are required to extend the functional life of stored turkey spermatozoa for artificial insemination. The present study evaluates the efficacy of a new extender (Turkey Semen Extend) and investigates the use of density gradient centrifugation in processing turkey spermatozoa for artificial insemination. The new extender is compared with two commercially available turkey semen extenders, Beltsville Poultry Semen Extender and Ovodyl. Turkey spermatozoa in Turkey Semen Extend were still motile 20 h after collection, representing a considerable improvement over the other semen extenders (40%, 0% and 8% for Turkey Semen Extend, Beltsville Poultry Semen Extender and Ovodyl, respectively). A field trial on a commercial turkey farm showed improved fertilization rates following insemination of turkey hens with semen extended in Turkey Semen Extend (89.7%) compared with Beltsville Poultry Semen Extender (86.9%). This difference is statistically significant (p < 0.05). Processing on a density gradient, optimized for turkey spermatozoa, also increased sperm survival (50% gradient-prepared spermatozoa still motile after 18 h compared with <10% non-processed spermatozoa). Preliminary studies indicate that gradient preparation of spermatozoa may aid survival during cryopreservation.

Gelatinases and serine proteinase inhibitors of seminal plasma and the reproductive tract of turkey (Meleagris gallopavo)

This study examined proteolytic enzymes and serine proteinase inhibitors in turkey seminal plasma with relation to their distribution within the reproductive tract and to yellow semen syndrome (YSS). Proteases of blood plasma, extracts from the reproductive tract, and seminal plasma were analyzed by gelatin zymography. We found a clear regional distribution of proteolytic enzymes in the turkey reproductive tract. Each part was characterized by a unique profile of serine proteolytic enzymes of molecular weights ranging from 29 to 88 kDa. The ductus deferens was found to be a site of very intense proteolytic activity. Two metalloproteases of 58 and 66 kDa were detected in all parts of the reproductive tract and seminal plasma. Using electrophoretic methods for detection of anti-trypsin activity, we found three serine proteinase inhibitors in turkey seminal plasma. Two inhibitors were found in the testis and epididymis and a third in the ductus deferens and seminal plasma. Blood plasma was characterized by the presence of two metalloproteinases and one serine proteinase inhibitor (of low migration rate) that were also detected in the reproductive tract. Amidase and anti-trypsin activities (expressed per gram of protein) differed for yellow and white seminal plasma. We concluded that turkey seminal plasma contains metalloproteases, serine proteinases, and serine proteinase inhibitors. The metalloproteases and one proteinase inhibitor are related to blood proteinases but the other two inhibitors and serine proteinases seem to be unique for the reproductive tract.

Role of seminal plasma in damage to turkey spermatozoa during in vitro storage

In vitro storage of turkey spermatozoa is performed without consideration of the potential role of seminal plasma on sperm functions. We report the effects of seminal plasma on membrane permeability, lipid metabolism, energy status, motility and fertility of turkey spermatozoa stored at 4 or 20 degrees C. Phospholipid content (1077 nmol/10(9) spz versus 1219 nmol/10(9) spz at 48 h) and membrane permeability of spermatozoa were significantly damaged by the presence of seminal plasma after 48 h of storage at 4 degrees C, whereas damage to ATP content and fertility occurred earlier damaged by this presence (fertility after 24h storage 51% with seminal plasma versus 71% without). At 20 degrees C, seminal plasma decreased the phospholipid content of spermatozoa in the first hour of storage (1326 nmol/10(9) spz versus 1636 nmol/10(9) spz). Twenty-four hours later, this effect was masked by intense lipid peroxidation. These results show that seminal plasma is deleterious to storage of turkey spermatozoa at 4 degrees C and is involved in phospholipid metabolism of spermatozoa. Lipid peroxidation could be responsible for the acceleration of the degradation of sperm phospholipids during storage at 20 degrees C. However, lipid peroxidation seems not to be active at 4 degrees C. In this case, we suggest that phospholipase activation may contribute to sperm degradation, especially in the presence of seminal plasma.

Membrane fluidity and the ability of domestic bird spermatozoa to survive cryopreservation

The ability to survive cryopreservation varies in spermatozoa from different bird species. Among the biological factors potentially responsible for such differences, species variations in membrane fluidity have a role in the restoration of the physiological state after freezing. Membrane fluidity may be assessed by measuring fluorescence polarization anisotropy with a fluorescent dye. Anistropy values are proportional to membrane rigidity and consequently inversely proportional to membrane fluidity. In the present study, polarization anisotropy of spermatozoa originating from species differing in the freezability of their semen (chicken, turkey and guinea fowl) was measured in addition to lipid composition (cholesterol/phospholipid ratio), sperm viability (membrane permeability to eosine) and morphological integrity before and after cryopreservation.

The percentages of viable and normal spermatozoa in fresh sperm were highest in the chicken (87%), lowest in guinea fowl (64%), and intermediate in turkeys (69%). Anisotropy values were highest in guinea fowl (0.205), lowest in chickens (0.155), and intermediate in turkeys (0.180). As a consequence, membrane fluidity was highest in chickens and lowest in guinea fowl. Cryopreservation significantly decreased sperm viability and morphological integrity and increased anisotropy in all species but did not change the inter species hierarchy. Initial cholesterol/phospholipid ratios were lower in chickens than in guinea fowl, and intermediate in turkeys (0.25, 0.26 and 0.29, respectively). Cryopreservation induced a severe decrease in cholesterol/phospholipid ratios in turkeys and guinea fowl.

Sperm membrane fluidity in chickens, turkeys and guinea fowl behaves as an indicator of sperm freezability in these species. Inter species differences for this parameter may be partly explained by differences in initial cholesterol/phospholipids content of spermatozoa. On the other hand, the rigidifying process induced by cryopreservation is not related to lipid damage by the same mechanisms.

Activity of phospholipases A and lysophospholipase in turkey semen and oviducal fluid

Changes in lipid composition of turkey semen have previously been reported to occur during in vitro storage and may be mediated by endogenous hydrolysis of phospholipids. To investigate the presence of phospholipases able to initiate such degradation, phospholipaseA2 (PLA2), phospholipase A1 (PLA1), and lysophospholipase (LPLase) activities were measured in turkey spermatozoa and seminal plasma. These enzymes were also measured in the oviductal fluid because they may be involved in the process prior to fertilization in the female. In spermatozoa and seminal plasma, the major PLA2 was a calcium-dependent and sodium deoxycholate (DOC) stimulated enzyme. However, calcium-independent PLA2 activities were also detected with different characteristics in spermatozoa (DOC inhibited enzyme) and seminal plasma (DOC stimulated enzyme). Additionally, PLA1 activity and high LPLase activity were present in spermatozoa and seminal plasma. In vitro storage of semen for 48 h did not affect PLA2 and LPLase activities. By contrast, PLA1 was the major phospholipase activity detected in oviductal fluid. A PLA2 activity stimulated by calcium or DOC and LPLase activity were also detected, but both were low relative to PLA1. These results showed that turkey semen had several enzymatic activities able to hydrolyze phospholipids. In addition, the phospholipase activities described here in the oviductal fluid could be involved in membrane destabilization prior to fertilization.

Effects of n-3 polyunsaturated dietary supplementation on the reproductive capacity of male turkeys

To measure the effects of dietary n-3 polyunsaturated fatty acid (PUFA) supplementation on the reproductive capacity of adult male turkeys in industrial flocks, the males of 22 commercial farms were fed either a standard diet or a fish oil diet enriched in n-3 PUFAs. The fatty acid composition of the spermatozoa and reproductive performance were measured throughout the reproductive period. The fish oil diet very effectively increased the percentage of n-3 fatty acids (FA) (22:5n-3 and 22:6n-3) in spermatozoa and correspondingly decreased the percentage of n-6 PUFAs (20:4-6 and 22:4n-6): the n-3/n-6 ratio in spermatozoa fatty acids were 0.04-0.07 with the standard diet and 0.32-0.4 with the fish oil diet. These changes did not affect the spermatozoa content of n-9 PUFAs, particularly of 22:3n-9 which is abundant in turkey spermatozoa (9-12% of the total fatty acids). The supplementation was effective in the middle as at the end of the reproductive period. The reproductive capacity of males was modified by the diet and the positive effect of the n-3 supplemented diet increased with age (increase in hatching rates of nearly 2 points at 48-58 weeks for males fed fish oil diet). These results indicate that an increase in the dietary ratio of n-3/n-6 PUFAs is valuable to sustain the reproductive capacity of male turkeys especially when they are getting older.

Impact of changes in composition of storage medium on lipid content and quality of turkey spermatozoa

Turkey semen quality is damaged by long term in vitro storage. The objective of the present study was to determine whether changes in energy substrates and antioxidants of semen extender could limit loss of quality and lipid content of turkey spermatozoa during storage. Spermatozoa were incubated in extenders based on Beltsville Poultry Semen Extender (BPSE) to which different energy substrates (acetate, pyruvate and hydroxybutyric acid) or antioxidant (Vitamin E) had been added. Semen was stored at 4 degrees C for 48 h and changes in quality, phospholipid and malondialdehyde (MDA) content of semen were evaluated. Among the different substrates studied, only acetate was able to limit the loss of motility and ATP content after 48 h in vitro storage. Losses of spermatozoal phospholipids were similar when gametes were incubated in an extender without any substrate or in normal BPSE (784-675nmol/10(9) spz versus 837-703 nmol/10(9) spz). However, motility and ATP content were significantly more affected after 48 h of storage in samples incubated without substrates than in BPSE (motility, 2.2 versus 0; ATP, 10 nmol/10(9) spz versus 3 nmol/10(9) spz). The addition of Vitamin E to the extender did not modify either the MDA or phospholipid content of fresh or stored spermatozoa, but increased the motility of stored semen. In conclusion, acetate is an essential substrate for in vitro storage. Spermatozoal phospholipids decreased during storage, but this did not seem to originate from metabolism of endogenous fatty acids. The positive effects of Vitamin E on semen storage did not originate from preservation of lipid oxidation.

Roles of antioxidants on prolonged storage of avian spermatozoa in vivo and in vitro

This review focuses on natural and assisted prevention against lipid peroxidation in avian spermatozoa. The presence of high levels of n-6 polyunsaturated fatty acids (PUFAs) in the plasma membrane creates favorable conditions for the formation of peroxidative products, a major cause of membrane damage which may ultimately impair male fertility. However, a complex antioxidant system involving vitamin C, vitamin E and GSH is naturally present in avian semen. Coupled with a battery of enzymatic defenses (e.g., SOD, GSH-Px either Se- or non-Se-dependent), this system acts to prevent or restrict the formation and propagation of peroxides. The presence of specialized sites dedicated to prolonged sperm storage in avian females raises the question of durable protection of sperm membranes against peroxidation. Preliminary observations have revealed the presence of a specific antioxidant system at these sites in which vitamin C could exert a major role. From a practical standpoint, the extensive use of artificial insemination in poultry, along with the emergence in some species of workable techniques to cryopreserve spermatozoa, demand better control of peroxidation occurring in the plasma membrane of spermatozoa before or during storage. Dietary supplementation with vitamin E is effective in limiting lipid peroxidation of sperm plasma membranes, both in chickens and turkeys. In addition, organic Se with or without vitamin E stimulates Se-GSH-Px activity in seminal plasma. Preliminary observations in female chickens have also revealed the effectiveness of dietary supplementation with vitamin E, organic selenium or both to sustain fertility in aging flocks.

Reproductive period affects lipid composition and quality of fresh and stored spermatozoa in Turkeys

Semen of Turkeys between 31 and 52 weeks of age was analyzed to investigate the cause of reduction in Turkey fertility at the end of the reproductive period. Sperm motility and viability, lipid concentration, fatty acid composition and lipid peroxides were evaluated on fresh spermatozoa or spermatozoa stored for 48h at 4 degrees C. Fertility of fresh semen was also evaluated. Fertility obtained with fresh semen decreased at 44-47 weeks of age. Ageing was also accompanied by a decrease in sperm viability (at 47 weeks) and later by a decrease in motility of spermatozoa (at 52 weeks). Polyunsaturated fatty acids (PUFAs) were the first lipids of fresh spermatozoa affected by age, especially n-3 and n-9 PUFAs. Changes in these PUFAs were followed by a 30% increase in lipid peroxidation at 47 and 52 weeks of age and a reduction in phospholipid content at 52 weeks. In vitro storage did not cause lipid peroxidation in sperm obtained during the first half of the reproductive period but malondialdehyde (MDA) levels significantly increased in sperm obtained during the second half of this period. In vitro storage also decreased phospholipid content of spermatozoa from 41 weeks of age, and viability and motility regardless of age. In conclusion, lipid alteration mainly originating from PUFAs peroxidation could partly explain the decrease in semen quality and fertility observed with ageing. In addition, lipid peroxidation was increased during in vitro storage of spermatozoa from older Turkeys.