Gonadotropin releasing hormone‐analogue (GnRHa) treatment improves the milt production and sperm motility of endangered Caspian brown trout,Salmo trutta caspius,over the course of a spawning season

To determine the effect of gonadotropin releasing hormone‐analogue (GnRHa) treatment on the milt quality of endangered Caspian brown trout, Salmo trutta caspius, the sperm motility (percentage and duration of motility), sperm production (sperm density, spermatocrit and milt volume) and milt pH were measured for GnRHa‐treated (the treatment group) and untreated groups (the control group) during the spawning season. For untreated brooders, the values of the motility per cent, sperm density and spermatocrit decreased continuously during the spawning season while the milt volume, duration of motility and milt pH showed only a significant decrease at the end of the season. For GnRHa‐treated males, these parameters increased 14 days after GnRHa treatment (first milt collection) and then decreased continuously towards the end of the season. In addition, the values of milt and sperm density yielded per treated male were higher than that in the untreated group, although these were not statistically different. In any case, the total sum of yielded milt from the treatment group over the spawning season was higher than that in the untreated group. In this experiment, significant positive correlations were found between milt parameters as follows: sperm motility vs. milt pH; sperm density vs. spermatocrit; milt volume vs. spermatocrit; and milt volume vs. sperm density. The results show that the treatment of Caspian brown trout by GnRHa can improve the milt quality in terms of sperm motility and sperm production during a spawning season.     

Seasonal Changes in the Milt Quality of Waigieu Seaperch,Psammoperca waigiensis: Implications for Artificial Propagation

Milt quality of Waigieu seaperch was sampled at the beginning, the middle, and the end of the spawning season to assess if the sampling season has an effect on milt quality parameters. The milt volume and total sperm production were higher at the middle of the spawning season while the sperm concentration in milt was significantly higher at the beginning and the end of the spawning season. Sperm morphology and the major parameters of seminal plasma (pH, total protein, Mg²⁺, or Ca²⁺ concentrations) did not differ throughout the spawning season. The concentrations of Na⁺ and the osmolality increased throughout the spawning season. The percentage of motile cells did not differ during the spawning season while the duration of sperm motility (swimming duration) and velocity (swimming speed) were significantly different during the spawning season. The fertilization rate (75.7 ± 6.8%) and hatching rate (56.5 ± 3.1%) at the middle of the spawning season were higher than at the beginning and end periods. Results indicated that milt quality parameters and fertility success in the middle of the spawning season were higher compared to earlier and later sampling dates. Thus, we recommend collecting milt during this time for maximal fertilization and hatching success.     

Spermiation time affect the milt quality indices of the Russian sturgeon,Acipenser gueldenstaedtii,Brandt & Ratzeburg, 1833

In this study, the effects of spermiation time are investigated on milt quality of Russian sturgeon over the course of the spawning season. The milt samples were collected from three broodstock batches at three time points including: the beginning, middle and at the end of the spawning season. According to the results, the milt quality parameters including pH, sperm density, spermatocrit, duration of sperm motility and percentage of sperm motility were significantly low in the beginning and end of season than middle of season. The values of milt quality parameters in the middle of season were as follows: (motility percentage: 69.6 ± 3.5, motility duration: 460.3 ± 37.2 s, sperm density: 8.7 ± 0.4 × 10⁹, milt volume: 86.3 ± 8.1 and milt pH: 8.3 ± 0.15). Significant positive correlations were also found between milt pH and sperm motility as well as between sperm density and spermatocrit. In conclusion, our study showed that the middle of season is the best time for collection of milt with appropriate quality in Russian sturgeon. Selection of milt with good quality is necessary aim to cryopreservation of spermatozoa in endangered fish species including Russian sturgeon.     

Seasonal changes in sperm production and quality in the red porgy Pagrus pagrus (L.)

Cultured red porgy Pagrus pagrus (L.) males (n=6) were sampled every 2 weeks for milt, in order to monitor changes in sperm quality parameters during a whole spawning period. On 11 January 2001, 60% of the fish were spermiating, increasing to 100% in mid‐February and dropping to 30% by mid‐April. Sperm density showed a slight increasing trend, with mean values ranging between 8.6 and 23.7×10⁹ spermatozoa mL^?1. Sperm motility percentage exhibited a significant improvement during the spawning season (analysis of variance (anova ) P=0.0001). The duration of forward motility for the major part of the monitoring period ranged between 2 and 4 min. Red porgy spermatozoa maintained their viability for many days after whole storage of milt at 4°C. During the monitoring period there were significant changes in the mean duration of sperm survival after cold storage, ranging from 5 to 12 days. The total volume of expressible milt was maximal on 28 March, increasing from a mean value of 1.7 mL to 5.3 mL kg^?1. Milt production of captive‐reared red porgy does not appear to be limiting, when compared with the volume of expressible milt produced by other cultured marine fishes.     

Motility Parameters of Rainbow Trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>) Spermatozoa in Relation to Sequential Collection of Milt,Time of <Emphasis Type="Italic">Post-mortem</Emphasis> Storage and Anesthesia

The present study investigated the effects of sequential collection of milt, time of post-mortem storage and anesthesia on rainbow trout (Oncorhynchus mykiss) sperm motility parameters (using computer-assisted sperm analysis – CASA) as well as seminal plasma osmolality and sperm concentration. The post-mortem storage and time of anesthesia altered motility characteristics of rainbow trout sperm to different extents. The moderate impact of time of anesthesia was manifested in a shortened duration of sperm motility after 10 min exposure of fish to anesthetic. The prolonged post-mortem storage (≥40–60 min), in addition to lowering sperm motility duration, also significantly influenced sperm motility parameters, such as sperm velocities, percentage of motile sperm and sperm trajectory parameters. These results clearly demonstrate that when milt from sacrificed fish is used for sperm motility studies, the time of post-mortem storage significantly alters sperm motility characteristics. Since sperm motility rate and swimming velocity could predict fertilizing ability, detrimental effects of prolonged post-mortem storage may lead to reduced fertilization success. Sperm concentration and seminal plasma osmolality were lower in the first fractions and increased with successive collections of milt. It suggests the presence of urine contamination of the first milt fractions which were collected by stripping. Therefore, testing of sperm concentration and/or seminal plasma osmolality should be mandatory while handling stored milt.     

Sperm density, seminal plasma composition and their physiological relationship in the endangered Caspian brown trout (Salmo trutta caspius)

Sperm density, mineral and organic composition of the seminal plasma and their physiological relationship were investigated in the Caspian brown trout (Salmo trutta caspius). To establish a rapid and accurate method for assessment of sperm density, three different techniques were used: sperm counting, spectrophotometry (at 480 nm) and determination of the spermatocrit. The seminal plasma contained 159.26±8.84 mM sodium (Na), 33.72±2.01 mM potassium (K), 133.04±5.96 mM chlorine (Cl), 1.68±0.2 mM calcium (Ca) and 0.988±0.13 mM magnesium (Mg). The following organic components were found: total protein 0.75±0.14 mg 100 mL⁻¹, cholesterol 2.86±0.58 mg L⁻¹ and glucose 3.81±1.04 mM L⁻¹. The mean sperm density was estimated to be 3.3 × 10⁹ spermatozoa mL⁻¹. The spermatocrit (%) ranged from 25 to 52 in sperm samples. Highly significant linear relationships were found between sperm density and spermatocrit (R²=0.703, P<0.001) and sperm density and optical density (R²=0.909, P<0.001), indicating that optical density can be used as a quick and accurate method of estimating sperm density. Significant relationships were also found between sperm density and Ca, Mg and total protein of seminal plasma. A significant correlation was also observed between the Ca and Mg concentrations (R²=0.774, P<0.01). The following correlations were observed between mineral and organic components: total protein and Ca (R²=0.462, P<0.05), total protein and Mg (R²=0.518, P<0.05) and glucose and Cl (R²=0.374, P<0.05). These parameters should be considered when developing procedures for either artificial fertilization or for cryopreservation of sperm.     

Changes in Atlantic cod (Gadus morhua L.) sperm quality during the spawning season

The biology of cod reproduction is well described in the scientific literature. However, sperm biology and spermatozoa management are poorly studied in this species. Because of its recent farming expansion, a better knowledge of cod gametes is becoming especially useful. This work aimed at establishing tools to study sperm biology in cod, and also investigated the existence of changes in cod sperm quality during the spawning period. We showed that sperm concentration could be assessed using spectrophotometry at 260 nm. Sperm motility significantly decreased after a 168‐h storage at 4 °C. A 1:9 dilution of sperm in a non‐activating medium (1/3 seawater and 2/3 freshwater, osmotic pressure: 360 mOsm kg^?1) improved sperm storage. Sperm concentration, sperm velocity and storage capacity at 4 °C peaked during the medium period of the spawning season and then decreased to values close to those observed at the beginning of the reproductive period. The measured values of osmotic pressure, pH, protein, Na⁺, Cl^? and Ca²⁺ concentrations of the seminal fluid were modified along the spawning period. Cell damage was noted at the end of the spawning period: local blebs were observed on the flagellum but also loops at its distal part. On the other hand, spermatocrit did not vary with the sampling date. In conclusion, cod sperm quality is modified during the spawning period, the highest‐quality samples being collected during the medium part of this season.     

Seasonal changes in the biochemistry of seminal plasma and sperm motility in the ocean pout,Macrozoarces americanus

Sperm motility, pH and osmolality of seminal plasma varied throughout the reproductive season spanning the period from June to September. Initially, sperm motility was low, peaked in July and August and then fell again towards the end of the spawning season. While the pH of seminal plasma increased from pH 7.4 to 7.9 during the period of spermiation, the average seasonal pH (7.78 ± 0.03) remained close to an experimentally determined optimum pH range for ocean pout sperm motility (pH 8–9). Likewise, although the values for seminal plasma osmolality fell during the reproductive season, from 416–339 mmol kg^-1, the average osmolality value 356 ± 3 was within the optimum for sperm motility (300–400 mmol kg^-1). In comparing fluctuations in sperm motility with the biochemical composition of ocean pout seminal plasma during the spawning season, this analysis showed that increased Mg⁺⁺ levels were correlated with the summer period of maximum sperm motility. A seasonal decline in Na⁺ and Cl⁻ ion levels was reflected in lower seminal plasma osmolality values.     

Sex steroids in the seminal fluid and milt quality indices in the endangered Caspian brown trout,Salmo trutta caspius

In this study, the relationships between the seminal fluid sex steroids sperm quality parameters (i.e. sperm motility and sperm production were investigated in the endangered Caspian brown trout. According to results, the variation of sex steroid concentrations was comparatively high. The seminal fluid levels of 17α‐Hydroxyprogesterone (OHP) had positive correlation with percentage and duration of sperm motility. Similar correlation was found between the seminal fluid concentration of testosterone (T) and estradiol‐17β (E2) with sperm concentration. As well as, there was no significant correlation between progesterone (P) with sperm quality indices. The significant correlation of some steroids i.e. OHP, T and E2 and sperm quality parameters of Caspian brown trout confirms the key role of these steroids in acquisition of the potential of motility during final stage of the maturation.     

Sperm quality of Brazilian flounder Paralichthys orbignyanus throughout the reproductive season

The aim of this study was to evaluate the sperm quality of Brazilian flounder Paralichthys orbignyanus throughout its reproductive season. Sperm was collected at the beginning, middle and end of the breeding period. Spermatozoa density was maximum at the beginning (12.7 ± 0.92 × 10⁹ cells mL^?1) and at the end (11.8 ± 0.39 × 10⁹ cells mL^?1) of the breeding season (P<0.05). Sperm production and the percentage of spermatozoa moving fast forward increased significantly towards the end of the breeding season (P<0.05). The mean duration of progressive motility of spermatozoa was around 10 min. No difference was observed during the reproductive season in the percentage of motile cells, pH, osmolality and K⁺, Cl^? and Mg²⁺ concentrations in seminal plasma. The concentration of Na⁺ increased throughout the breeding season, reaching 174.62 ± 12.68 mmol L^?1 at the end (P<0.05). There was a decline in the concentration of Ca²⁺ (12.31 ± 3.08 mmol L^?1) in the middle of the breeding season, which coincided with the shortest motility duration of spermatozoa. The information reported in this study should help to improve management and optimize the development of protocols for short‐term storage and cryopreservation of Brazilian flounder semen.     

Sperm quality in male <Emphasis Type="Italic">Barbus barbus</Emphasis> L. fed different diets during the spawning season

Sperm quality of Barbus barbus L. was compared among the three following dietary regimes: Group A, fed 100% commercial diet (Karpico™ containing 33% crude protein and 6% fat), Group B, fed 78% commercial diet and 22% frozen chironomid (Chironomus plumosus) larvae, and Group C, fed 56% commercial diet and 44% frozen chironomid larvae. Concentrations of polyunsaturated fatty acids (PUFAs) in Group A, B, and C were 39.1, 42.0, and 44.6, respectively, as a percentage of total fatty acids. Sperm morphology, volume, concentration and motility, total number of spermatozoa, and osmolality of the seminal plasma were compared during the spawning season. Dietary regime did not influence sperm volume, concentration, or total number of spermatozoa, osmolality of seminal plasma, or the percentage of motile sperm, but significantly affected sperm morphology (except for anterior and posterior parts of the midpiece) and sperm velocity (P < 0.05). Groups B and C showed similar sperm characteristics during the spawning season compared to Group A. Almost all parameters changed either among or within groups during the spawning season, suggesting differences in terms of the optimal time for sperm collection. The best time for sperm collection was March for Group A, but April for Groups B and C, when the osmolality of the seminal plasma measured 289 mOsmol kg⁻¹ and sperm motility was maximal. Spermatogenesis, hydration, and cell decomposition were confirmed as the three major parameters controlling sperm characteristics during the spawning season. The possible correlation between sperm morphology and motility requires further study.     

Sperm motility and seminal plasma characteristics in Barbus sharpeyi (Günther, 1874)

Spermatozoa concentration, ionic composition, osmolality, glucose and total protein contents of seminal plasma and sperm motility were determined in Barbus sharpeyi (Cyprinidae, Teleosotei). Spermatozoa concentration ranged from 9.77 to 20.20 × 10⁹ spermatozoa mL^?1. Osmolality (mOsmol kg^?1) and ionic contents (mM L^?1) of the seminal plasma were 274.5±9.0, 70.0±3.4 Na⁺, 28.8±0.9 K⁺, 101.7±3.1 Cl^?, 0.9±0.1 Mg²⁺ and 2.1±0.1 Ca²⁺ respectively. Total protein and glucose were 5.3±0.2 g L^?1 and 76.7±4.3 mM L^?1 respectively. Sperm motility was initiated in a hypo‐osmotic condition, composed of either an ionic (KCl or NaCl) or a non‐ionic (sucrose) activation medium. Duration of sperm motility was very short: <2 min after activation in distilled water. Percentage of motile spermatozoa was significantly higher in an activation medium containing NaCl compared with that of distilled water. An activating medium containing NaCl or KCl higher than 150 mM or sucrose higher than 275 mM totally inhibited the activation of sperm motility. Immediately after sperm activation, wave(s) propagated along the flagellum, but waves were restricted to the proximal part of the flagellum (close to the head) at 1 min post activation. Studied characteristics in the present study were compared with those of other cyprinids for understanding inter‐species differences.     

Effect of two commercial preparations containing different GnRH analogues with dopamine antagonists on barbel Barbus barbus (L.) sperm quantity and quality

The effectiveness of applying Ovaprim [(D-Arg⁶, Pro⁹NEt)-sGnRH + domperidone] and Ovopel [(D-Ala⁶, Pro⁹NEt)-mGnRH + metoclopramide] to male barbel Barbus barbus (L.) 6, 12 and 24 h after hormonal stimulation was analyzed. The control group (Control) during each time interval was stimulated with 0.9 % NaCl. Milt was collected from seven fish only once (n = 7) for Ovopel, Ovaprim and Control group in order to determine total volume of milt, volume of milt per kg of body weight, sperm concentration, total sperm production, seminal plasma osmotic pressure, pH of milt and pH of seminal plasma. Woynarovich’s solution (68 mM NaCl + 50 mM urea) with the addition of 0.5 % BSA (pH 7.7; 181 mOsm kg^?1) was used as the activating liquid. Selected parameters of sperm motility (MOT %) and progressively motile sperm (%), curvilinear velocity (VCL, μm s^?1), straight-line velocity (μm s^?1), movement linearity (%), wobbling index (%), amplitude of lateral head displacement (μm) and beat cross frequency (Hz) were determined using the Computer-assisted sperm analysis system. A time of 6 h proved to be too short to obtain milt from barbel following hormonal stimulation with Ovaprim and Ovopel. Extending the time to 12 h, however, resulted in 100 % spermiation in males, regardless of hormonal preparation used for stimulation. The stimulation of spermiation in barbel is best performed using Ovopel 12 h upon application. Extending the latency period to 24 h following the application of this preparation results in a significant decrease in the volume of milt obtained, sperm count and motility parameters, including MOT and VCL, which may influence sperm fertilization ability.     

Sperm motility and fertilizing ability in the Persian sturgeon Acipenser persicus

The motility and fertilizing ability of the Persian sturgeon, Acipenser persicus, spermatozoa were investigated. Optimum ionic content (Na⁺, K⁺, Ca²⁺ and Mg²⁺) and pH of activation solution as well as the optimum dilution rate were determined. The results show optimum motility characteristics of spermatozoa in buffered solutions containing 25, 0.2, 3 and 10 mM L^?1 Na⁺, K⁺, Ca²⁺ and Mg²⁺, respectively, at dilution rate 1:50 and pH 8.0. To test the fertilizing ability of sperm, two buffered saline solutions were used as activation solution of sperm motility. The present study indicated (1) spermatozoa motility is one of key factors that influence on fertilizing ability of sperm, (2) a high fertilizing ability of sperm is obtained after dilution in saline solutions rather than in freshwater and (3) a maximum fertilization rate occurs in buffered saline solution containing 0.2 mM L^?1 K⁺. There is also a good correlation between biochemical characteristics of seminal plasma and fertilizing ability of sperm.     

Effect of GnRHa injection on milt volume in recently stripped rainbow trout Oncorhynchus mykiss

In this study, the effect of gonadotropin‐releasing hormone agonist (GnRHa) injection on milt production in spent rainbow trout was investigated. On day 0, 25 newly matured male rainbow trout (Oncorhynchus mykiss) were stripped manually, and sperm quantity (vol: mL fish^?1) and quality, spermatocrit (%), sperm count (cell mL^?1), motile sperm percentage and motility duration (s) were evaluated. After stripping, fish were randomly divided into five groups: intact; sham (injected with propylene glycol as a hormone vehicle); and groups receiving 4, 8 or 16 μg kg^?1 BW of [d ‐Ala⁶ Des‐Gly¹⁰] mGnRHa. On day 7, the fish were stripped again and the same sperm characteristics as on day 0 were measured. At the beginning of the experiment, there were no significant differences in any of the sperm quantity characteristics between groups. On day 7, expressible milt volume was significantly reduced compared with day 0 (P<0.05, t‐test) in the intact and sham groups but milt quality remained the same (P>0.05, t‐test). The present study shows that GnRHa injection with a concentration as low as 4 μg kg^?1 BW after first stripping could prevent a significant reduction in milt quantity collected 7 days later without any adverse effects on sperm quality.     

Estimation of sperm concentration of wild and reconditioned brown trout, Salmo trutta L.

Sperm concentrations were assessed for milt samples taken from three stocks of brown trout, Salmo trutta L., (wild resident trout, and reconditioned and seareared sea trout) using direct counts, spermatocrit and an optical density of 1:1000 dilutions. There were significant linear relationships between spermatocrit and absorbance, and both spermatocrit and absorbance with sperm concentration. The results gave sperm concentrations from 2.2 × 10⁹ mL^?1 to 26 × 10⁹ mL^?1. Mean concentrations differed significantly between stocks; the reconditioned males had a mean concentration of 9.1 × 10⁹ mL^?1, sea-reared males 18.0 × 10⁹ mL^?1 and 8.0 × 10⁹ mL^?1 in 1994 and 1995, respectively, and wild resident males 13.3 × 10⁹ mL^?1. Sperm concentrations from all three stocks of trout were negatively correlated with length, and therefore, age. It was indicated that sufficient milt was being produced to achieve good rates of fertilization, although some of the larger trout did have low sperm counts, suggesting that fertilizing ability may decrease with male size or age within any one stock.     

Characterization of rainbow trout milt collected with a catheter: semen parameters and cryopreservation success

Collection of fish milt by stripping risks the danger of milt contamination by urine. This may seriously influence milt characteristics and quality, including usefulness for cryopreservation. Urine contamination of milt may be avoided by using a catheter for sperm collection. The objectives of this study were to provide basic characteristics of milt collected with a catheter, to test the usefulness of this milt for cryopreservation, and to correlate characteristics of fresh and cryopreserved semen with sperm fertility rates. Milt from 25 rainbow trout Oncorhynchus mykiss (Walbaum) males were used. All samples were cryopreserved using the pellet method within 1 h of collection, using 0.6 m sucrose and 10% dimethyl sulphoxide (DMSO) as an extender. Catheterization resulted in semen of very good motility (> 90% motile spermatozoa) and high fertilization rates after cryopreservation (mean fertilization rate 81.8 ± 13.3% of control, at a sperm/egg ratio of 2.4 ± 0.3 × 10⁶). Osmolality of seminal plasma and concentrations of sodium, potassium and magnesium ions had low variability, which suggests that they are important for creating a stable environment for sperm storage in the sperm duct. Higher variability of certain seminal plasma characteristics, such as protein concentration and antiproteinase activity, suggests that these characteristics are related to individual semen features of particular males. A strong correlation of seminal plasma zinc concentration with protein concentration may reflect an importance of zinc in semen biology. Cryopreservation caused a significant release of protein and acid phosphatase from spermatozoa. Our results did not reveal any single characteristic of semen collected by catheter that could be used as a powerful predictor of cryopreservation success, presumably because all samples were of high quality.     

Antibiotics,Penicillin and Sreptomycin improve semen quality indices of endangered Caspian brown trout,Salmo trutta caspius (Kessler, 1870) during in vitro short‐term storage

In this study, we examined the effects of 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate on semen quality indices of endangered caspian brown during 12 days short‐term storage at 4°C. Twenty‐four millilitre semen samples with good quality were considered for the experiment. The semen samples were then stored in the presence and absence of 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate. The semen quality parameters including percentage and duration of sperm motility were measured 0, 3, 6, 9 and 12 days after storage. In the antibiotic receiving group, the values of percentage and duration of sperm motility reduced 3 and 6 days after storage respectively and reduced to lowest levels at day 12. In the antibiotic‐free group, the duration and percentage of sperm motility decreased significantly after 3 days of storage and reached to lowest values at day 12. Also, percentage and duration of sperm motility in each storage time were significantly higher in the antibiotic receiving group than in the antibiotic‐free group. The overall values of percentage and duration of sperm motility for all storage periods were higher in the antibiotic receiving group than in the antibiotic‐free group. In conclusion, our results demonstrated that 500 IU mL^?1 penicillin + 500 μg mL^?1 streptomycin sulphate improves the viability of caspian brown trout during short‐term storage.     

Production and storage of sperm from the black sea bass Centropristis striata L

Black sea bass Centropristis striata L. are protogynous hermaphrodites that develop and spawn as females before changing sex to male. Since all fish eventually become males, determining the relationship between sperm production, sperm quality and seasonal changes in plasma levels of testosterone (T) and 11‐ketotestosterone (11‐KT) could be useful for identifying appropriate males to maintain as broodstock. Milt and blood samples were collected three times during an 8‐week spawning season. Milt volume (3.5±0.76 mL kg^?1), sperm density (3.2 × 10⁸± 0.31 cells mL^?1), sperm production [11 × 10⁸±3.4 cells kg^?1 body weight (BW)] and sperm motility (80±0.6%) were at their highest during the first sampling interval and coincided with the highest 11‐KT levels (1.0± 0.11 ng mL^?1). All of the sperm indices decreased to their lowest levels during the final 3 weeks of the study. Sperm viability was highly correlated (adjusted R²=0.84) with sperm motility. Sperm cryopreserved in modified Mounib's extender (MME) had the highest post‐thaw motility compared with two other extenders. Post‐thaw motility of sperm cryopreserved in MME was not different from fresh after 90 days of storage. There was no difference in fertilization rates between fresh (69±2.4%) and post‐thaw (67±4.1%) sperm samples taken from the same male or among males. These results demonstrate that the quality of black sea bass spermatozoa is higher earlier in the spawning season and that acceptable post‐thaw fertilization rates can be obtained from cryopreserved sperm.     

Biochemical Composition of Seminal Plasma and Annual Variations in Semen Characteristics of Jundiá <Emphasis Type="Italic">Rhamdia quelen</Emphasis> (Quoy and Gaimard,Pimelodidae)

This study investigated the composition of milt of the South American silver catfish (Rhamdia quelen) or jundiá. The semen was taken from jundiá in different periods during the four seasons. The biochemical composition of seminal fluid and the characteristics of sperm were analyzed. The semen quantity which can be extracted per fish in one day was 0.95 ± 0.08 ml during spring (maximum) and 0.24 ± 0.03 ml during winter (minimum). Sperm density (spermatocrit) showed higher values in the spring (75.1 ± 1.3%) decreasing slightly afterwards and reaching 63.0 ± 2.4% to 65.0 ± 2.2% in the fall and winter. Immediately after water dilution, 90–100% of the spermatozoa presented vigorous straightforward motility that remained for at least 20 s. The total duration of the motility was 47.9 ± 1.3 s in the spring and 38.6 ± 0.6 s in the other seasons (P < 0.05). This pattern of motility is maintained for more than 2 h after storage of the milt at room temperature. The pH from 5 to 10 of the water dilution does not influence the sperm motility. The mean seminal pH and osmolality values were 8.7 ± 0.07 and 274.8 ± 11.2 (mOsm/kg), respectively. The ion concentration was: Na 153.7 ± 2.4, K 10.7 ± 2.4, Cl 139.4 ± 2.1, Ca 4.2 ± 0.2, Mg 0.9 ± 0.05, P 0.9 ± 0.08 (mEq/l). The total protein was 0.6 ± 0.05 mg/dl and cholesterol concentration was 13.9 ± 0.9 mg/dl.