Effect of Ram Age on Structural and Functional Competence of Frozen–Thawed Spermatozoa in Dairy Sheep

The objectives of this study were to investigate the influence of ram age on structural and functional competence of frozen–thawed spermatozoa and to test the hypothesis that increasing number of sperm bound to the zona pellucida in vitro was associated with decreasing in vivo fertility of frozen semen. Rams were allocated into two groups. Each group consisted of five rams aged either 1–2 years (young) or 4–5 years (mature). Three successive ejaculates were collected from each ram using an artificial vagina. Only ejaculates of ≥ 2.5 × 10⁹ sperm/ml and 80% sperm progressive motility were pooled per ram, diluted with Bioxcell^® medium and frozen in 0.25 ml straws. The end points of post‐thawing semen evaluation were computer‐assisted cell motility analysis, sperm capacitation (chlortetracycline assay), simultaneous assessment of plasma membrane integrity, mitochondrial membrane potential and condensation status of nucleus, per‐cell analysis of lipid peroxidation using C11‐BODIPY^581/591, sperm‐hemizona binding (HZB) ability and sperm fertility after laparoscopic insemination of ewes (n = 114) in the progestagen‐synchronized oestrus. The results showed that mature rams had significantly lower values of sperm hyperactivated motility and peroxidized sperm, higher percentages of live non‐capacitated sperm and sperm cells with intact plasma membrane, functional mitochondria and condensed chromatin, as well as, greater lambing rate and ewe prolificacy. Sperm HZB binding ability was higher (p < 0.05) for young than for mature rams. Significant correlations were found between number of spermatozoa bound to the zona pellucida and semen fertility (r = ?0.63 to ?0.71). In conclusion, mature rams have better semen quality and in vivo fertility than young rams. Cryocapacitation can be involved in decreasing ram semen fertility as evidenced by the high number of spermatozoa bound to the zona pellucida in vitro.     

Composition of seminal plasma and ovarian fluid in Ide Leuciscus idus and Northern pike Esox lucius

Seminal plasma (SP) and ovarian fluid (OF) plays an important role as storage media to prevent the activation of gametes both in vivo and under artificial conditions. The objectives of this study were to quantify gamete biochemistry and explore correlations among quantitative characteristics of SP, OF and sperm performance traits of Ide Leuciscus idus and Northern pike Esox lucius. Generally, Na⁺, K⁺ and Cl^? were found to be the most dominating ions, although concentrations of K⁺ were higher in SP, while Na⁺ and Cl^? concentrations were higher in OF for both species. Several significant correlations among the biochemical properties such as total protein, glucose, osmolality, cholesterol, K⁺, Ca²⁺, Cl^? and Mg²⁺ were observed for SP and OF. Total protein content of Ide SP was positively correlated with sperm activity traits (r ≥ .89, p ≤ .05), while K⁺ concentration was negatively correlated with sperm traits (r ≥ ?.89, p ≤ .05). Moreover, Ca²⁺ concentration in Northern pike SP was positively correlated with the percentage of sperm motility (r = . 98, p < .01). In conclusion, these results can be used to better understand the biochemistry of SP and OF, improve methods for short‐ and long‐term storage of gametes and standardize fertilization protocols.     

Seasonal variations in sexual behavior, testosterone, testicular size and semen characteristics, as affected by social dominance, of tropical hair rams (Ovis aries)

The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behavior and testosterone concentration (T4) in dominant and subordinate Pelibuey rams. Six groups of three animals were evaluated every 2 weeks over a 12 month period. Dominant (D), medium (M) and subordinate (S) animals in each group were identified through a food competition test every 15 days. All rams ejaculated and produced semen throughout the year. A linear hierarchy was clearly established and maintained during the year. S rams had lower levels (P < 0.05) of semen volume, sperm concentration and testicular volume than D rams, regardless of season. Scrotal circumference was not influenced (P > 0.05) by their social position. D rams were more affected by the photoperiod, decreasing (P < 0.05) reaction times, increasing (P < 0.05) T₄ and producing more (P < 0.05) sperm per ejaculation than S rams during short days (14.65 ± 1.22 vs 26.92 ± 1.65 s; 8.68 ± 0.44 vs 7.37 ± 0.40 ng/mL and 3.37 ± 0.17 vs 2.04 ± 0.16 sperm/10⁹, respectively). Semen volume and sperm concentration were significantly (P < 0.05) greater during short days in all rams, regardless of their social status, with the exception of sperm concentration in D rams where no variation was found. M rams displayed variable values in the range between the D and S rams. It was concluded that the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year and that seasonal variation within the variables affected the social ranks differently.     

Effects of Melatonin Implants During Non‐Breeding Season on Sperm Motility and Reproductive Parameters in Rasa Aragonesa Rams

The effect of melatonin implants administered during non‐breeding season in Rasa Aragonesa rams on sperm motility parameters and other reproductive traits was assessed. In a first experiment, two Rasa Aragonesa rams were implanted (with melatonin group M), remaining other two males as control group (C). Semen of each group was collected from 1 May to 23 June, twice or three times a week, and motility parameters were assessed using a computer‐assisted sperm analysis system. Melatonin increased the percentage of progressive motile spermatozoa, particularly during 46–75 days after melatonin implantation (p < 0.01). In experiment 2, M and C in vitro fertilization ability had been determined by zona‐pellucida binding assays, using spermatozoa from experiment 1, obtained 60–70 days after melatonin was implanted. A significantly higher number of spermatozoa attached per oocyte was observed in frozen‐thawed immature ovine oocytes incubated with sperm from M animals than in those incubated with sperm from the C group (p < 0.01). Finally, a field assay (experiment 3) was performed. In this case, five Rasa Aragonesa rams were implanted with melatonin and three remained as control group. Sperm doses from those animals were used for artificial insemination of 2608 Rasa Aragonesa ewes from 39 different farms at non‐breeding season. Fertility, litter size and fecundity were studied. Semen from melatonin implanted rams seemed to increase both fertility and fecundity in ewes inseminated with spermatozoa obtained 46–60 days after implantation (p < 0.1). Thus, melatonin treatment in rams during non‐breeding season modifies sperm motility parameters and seems to improve the fertilization parameters obtained.     

The Relationship Between Post‐Thaw Sperm DNA Integrity and Non‐Return Rate Among Norwegian Cross‐Bred Rams

With the aim of investigating the relationship between sperm DNA integrity and non‐return rate (NRR) among Norwegian cross‐bred rams, semen from 15 individuals was examined by flow cytometry. Sperm Chromatin Structure Assay (SCSA) quantifies the proportion of spermatozoa with denatured DNA after in situ acid treatment, and the four parameters % DFI, % HDS, MEAN DFI and SD DFI are all different measures of DNA denaturation and maturation. Field fertility, reported as NRR 25 days after insemination was based on all inseminations from a large‐scale breeding programme and supplied by the Norwegian Association of Sheep and Goat Farmers. From each ram, four straws from four different weeks of the breeding season were analysed, and the associations between 25‐day NRR and the mean of the four SCSA parameters were tested using a logistic regression model. The results revealed no association between fertility and % DFI or % HDS, while SD DFI and MEAN DFI showed a significant negative association with NRR. Further, the SCSA values varied significantly between ejaculates within ram among some of the rams in the study. However, no significant association was seen between these intra‐individual differences in sperm DNA integrity and NRR. In conclusion, this study suggests an association between sperm DNA integrity and NRR for rams. However, further research must be conducted to confirm these findings and determine whether sperm DNA assessments can be applied to predict ram fertility.     

Implications of ram sperm rheotaxis analysed by microfluidics for fertility

Rheotaxis of sperm using a microfluidic device was explored in human, mice and bull. However, the rheotaxis of ram sperm and its role in fertility are unknown. Herein, we described the sperm rheotaxis in ram using microfluidic devices and focused on rheotaxis as potential markers of in vivo fertility. Computer-assisted sperm analysis (CASA) with controlled flow velocity was used to explore the kinematic parameters of sperm, total motility and positive rheotaxis (PR). The percentage of PR was defined as the number of PR sperm cells over the number of motile sperm cells. Then, according to the percentage of PR sperm, rams were classified into two groups; sperm with ≥40% PR and <40% PR, although the two ram groups showed similar total motility and kinematic values of sperm evaluated by CASA (p > .05). Two groups of rams mated one hundred thirty ewes naturally (10 ewes/ram). In the results, the pregnancy rate was higher in ≥40% PR (94.4%) than in <40% PR (42.5%, p < .05) after natural mating. Besides, the pregnancy loss was higher in <40% PR (33.3%) than in >40% PR group (8.1%, p < .05). In conclusion, the PR examination in semen can contribute to evaluate the reproductive performance of ram that will provide valuable insights into the semen evaluation.     

Linseed oil in boar's diet improved in vivo fertility and antioxidant status

The reactive oxygen species (ROS) which are produced during storage of boar semen are causing oxidative stress and leads to poor fertility. Also, tropical and sub-tropical weather condition adversely impacts the physicomorphological quality and fertility of boar sperm. The aim of this study was to examine the effects of feeding linseed oil to boar on its seminal attributes, sperm kinetics, biomarkers of antioxidant, fatty acid profile of seminal plasma (SP) and sperm and in vivo fertility. Six Hampshire crossbreed boars were fed with 90 ml linseed oil (LIN) whereas six Hampshire crossbreed boars were fed 90 ml canola oil (CON) for 16 weeks. Sperm quality was evaluated (60 ejaculates for each group; a total of 120 ejaculates) for motility, livability, abnormal morphology, acrosomal membrane integrity, hypo-osmotic swelling test (HOST) and sperm kinetic parameters by computer assisted semen analysis (CASA) at 0 h and at 72 h of storage at 17°C. Biomarkers of antioxidant (glutathione peroxidase; GPx, catalase; CAT, total antioxidant capacity; TAC) and malondialdehyde (MDA) were measured in SP and serum. Gas chromatography–mass spectrometry (GC–MS) was used for the estimation of fatty acid composition of SP and sperm. Boars fed with linseed oil had higher semen volume (p < .01) and more total sperm numbers (p < .01). Feeding linseed oil to boar enhanced seminal attributes (p < .05) at 0 h as well as at 72 h of storage. Linseed oil feeding (p < .01) improved biomarkers of antioxidants and significantly (p < .01) lowered the lipid peroxidation in serum and SP. Linseed oil feeding (p < .05) increased the proportion of alpha linolenic (ALA), arachidonic and docosahexaenoic (DHA) fatty acids in SP. The ratio of n-6 to n-3 fatty acids in sperm increased significantly (p < .01) in treatment group. Farrowing rate was significantly (p < .05) higher in treatment group. In conclusion, feeding linseed oil to boar improved the in vivo fertility, enhanced antioxidant capacity and increased the DHA content of SP and sperm.     

Effects of the Addition of Autologous Seminal Plasma to Highly Concentrated Stallion Semen After 48 Hours of Cooled Storage

Insemination with chilled transported semen has become distinctly important in the horse-breeding industry. To ensure cell survival during cooled storage, semen is diluted with an appropriate extender and the concentration of seminal plasma (SP) is reduced. Nevertheless, SP plays an important immunomodulatory role in the female genital tract and supports sperm fertility. The aim of the present study was to evaluate the effect of the addition of autologous SP after cooled storage to highly concentrated stallion semen. Therefore, SP was removed by simple centrifugation of extended semen, aspiration of the supernatant, and resuspension of the sperm pellet with semen extender. Motion characteristics were evaluated after cooled storage for 48 hours at concentrations of 333 × 10⁶ sperm/mL in comparison with stored samples at concentration of 25 × 10⁶ sperm/mL (control). The highly concentrated semen samples were diluted with an extender containing 0%, 5%, 20%, and 80% SP directly before motility analysis. Dilution of the cooled semen with a fresh semen extender without SP (0%) increased kinematic parameters (curvilinear velocity [VCL] 137.3 vs. 151.8; straight-line velocity [VSL] 49.0 vs. 57.5; average path velocity [VAP] 69.5 vs. 79.4 μm/second; amplitude of lateral head [ALH] 3.1 vs. 3.3 μm; beat cross frequency [BCF] 31.6 vs. 33.5 Hz; P < .05) but not total motility (51% vs. 43%) and progressive motility (46% vs. 36%) compared with controls. The addition of SP after storage for 48 hours decreased sperm total motility and progressive motility regardless of SP concentration: 5 (38% and 34%), 20 (37% and 33%), and 80% SP (27% and 22%; P < .05). In contrast, kinematic parameters were enhanced by extenders containing 5% and 20% SP (VCL: 148.0 and 155.6; VSL: 59.2 and 60.9; VAP: 78.7 and 81.9; BCF: 33.4 and 35.7; ALH: 3.4 and 3.4; P < .05). However, using an extender containing 80% SP was detrimental to kinematic parameters (VCL: 151.2; VSL: 52.2; VAP: 76.9; BCF: 34.8; P < .05) except for ALH, which increased (3.5; P < .05). In conclusion, cooled storage at concentrations of 333 × 10⁶ sperm/mL did not affect sperm motility. The addition of a fresh extender or an extender containing small concentrations of SP to highly concentrated ejaculated sperm increased kinematic values after storage; however, increasing concentrations of SP decreased sperm motility.     

Effect of Seminal Plasma on Post‐Thaw Quality and Functionality of Corriedale Ram Sperm Obtained by Electroejaculation and Artificial Vagina

We have already shown that seminal collection method affects seminal plasma composition and sperm quality in Corriedale rams. In this study, we evaluated the effect of seminal plasma collected by electroejaculation or artificial vagina on sperm resistance to cryodamage. Seminal plasma of five rams of the Corriedale breed collected by artificial vagina or electroejaculation was added before freezing to sperm cells collected by the two methods, and post‐thaw quality parameters were evaluated. We found that seminal plasma has no effect on sperm resistance to cryodamage. However, we observed significantly higher percentages of sperm with intact and functional plasma membrane, intact acrosome and greater fertilizing potential after thawing in samples obtained by electroejaculation. This study demonstrates that sperm collected by electroejaculation are more resistant to damage caused by cryopreservation than those collected by artificial vagina.     

Effect of semen collection frequency on seasonal variation in sexual behaviour,testosterone, testicular size and semen characteristics of tropical hair rams (<Emphasis Type="Italic">Ovis aries</Emphasis>)

The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behaviour and testosterone (T4) concentration in Pelibuey rams subjected to different semen collection frequencies. Eighteen intact males were assigned randomly to one of two semen collection frequencies: in the high rate (HR) treatment, two ejaculations per week were obtained from each ram; one ejaculation every two weeks was collected under the low rate (LR) treatment. All animals were housed individually in contiguous 5 m × 5 m wire mesh pens and evaluated over a 12-month period. At the beginning of the experiment rams were 20 months old and 40–50 kg in weight. All rams ejaculated and produced semen throughout the year. Semen volume, sperm per ejaculation, testicular circumference and testicular volume were significantly (p < 0.05) greater during short days in all rams, regardless of the semen collection frequency, with the exception of sperm concentration, for which no variation was found in HR individuals, and reaction time and T₄ levels, for which no variation was found in LR males. Rams subjected to HR collection were more affected by the short-day photoperiod than rams collected twice per week, exhibiting greater reduction (p < 0.05) in time to achieve their first ejaculation and in sperm per ejaculation, as well as greater increases (p < 0.05) in T₄ concentration than LR rams (14.65 ± 1.22 vs 23.53 ± 5.34 s, (3.37 ± 0.17) × 10⁹ vs (3.52 ± 0.20) × 10⁹ sperm and 8.68 ± 0.44 vs 6.85 ± 0.74 ng/ml, respectively). It was concluded that: (a) the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year, and (b) seasonal variation within variables was affected differently between semen collection frequencies.     

Melatonin administration enhances the reproductive capacity of young rams under a southern Mediterranean environment

This study tested the effect of melatonin treatment, initiated in late February on reproductive traits of young rams. A total of 14 young Barbarine rams were used. Seven animals were treated with three melatonin subcutaneous implants (Melatonin) on 28 February while the remaining rams remained untreated (Control). After 60 days of melatonin administration, scrotal circumference reached average values of 32.1 ± 1.54 and 29.5 ± 1.0 cm for Melatonin and Control animals, respectively (P < 0.05). Semen characteristics did not differ between groups; melatonin treatment tended (P = 0.091) to increase sperm concentration 60 days after implantation when means reached 5.87 ± 0.703 and 4.61 ± 0.654 × 10⁹ spermatozoa/mL for Melatonin and Control rams, respectively. Melatonin treatment significantly affected total activity time, number of lateral approaches and mount attempts in comparison to controls. During a 6‐h sampling period, mean plasma testosterone concentrations increased as a result of melatonin treatment (P < 0.001) and testosterone pulse frequency averaged 3.45 ± 2.24 and 1.25 ± 1.0 (P = 0.086) for Melatonin and Control rams. Data clearly suggest that abrupt treatment of young rams with melatonin implants in winter is sufficient to improve reproductive traits.     

Effect of induced body condition score differences on sexual behavior,scrotal measurements,semen attributes and endocrine responses in Malpura rams under hot semi‐arid environment

The study was conducted for a period of 45 days to assess the influence of body condition scoring (BCS) on reproductive efficiency of Malpura rams in terms of sexual behaviour, scrotal measurements, semen attributes and endocrine responses. The rams were randomly divided into three groups as group I (BCS = 2.5; n = 7), group II (BCS = 3.0; n = 7) and group III (BCS = 4.0; n = 7). Apart from grazing for 8 h a day, the rams were provided with concentrate mixture at the rate of 100, 300 and 500 g to groups I, II and III respectively to attain their respective BCS. Under these differential feeding regimes, sexual behaviour scrotal measurements, semen characteristics and endocrine parameters were studied at 15‐days interval. Sexual behaviour, scrotal volume, scrotal circumference, testicular width, testicular length and scrotal skin thickness differed significantly (p < 0.05) between lower BCS group (group I) and higher BCS groups (groups II and III). The semen volume, mass motility and progressive sperm motility were recorded significantly (p < 0.05) higher in group II and lowest in group I. However, the sperm concentration did not differ significantly between the groups. The mean plasma testosterone concentration differed significantly (p < 0.05) between lower BCS group (group I) and higher BCS groups (groups II and III). Circulating plasma hormone concentrations were influenced due to the BCS. Plasma cortisol, T₃ and T₄ increased as the BCS improved from lower to higher. In conclusion, better reproductive efficiency of rams of moderate BCS (3.0 and 3.5) than rams of lower (2.5) and higher BCS (4.0) indicates the importance of maintaining optimum body condition of breeding rams under hot semi‐arid environment.     

Influence of feeding level on live body weight and semen characteristics of Sardinian rams reared under intensive conditions

The aim of the present study was to assess the effects feeding level on body weight changes and semen parameters in adult Sardinian rams reared under intensive conditions in a semi-arid area of southern Italy. During an experimental period of 90 days, 24 healthy Sardinian rams were divided into three equal groups that differed in their feeding level, in terms of concentrate amount. The control-concentrate (CC; n = 8) group received 1.0 times their maintenance requirements, the medium-concentrate (MC; n = 8) group received a diet that supplied 1.2 times their maintenance requirements, and high-concentrate (HC, n = 8) group received a diet that supplied 1.5 times their maintenance requirements. Mixed vetch–oat hay was offered ad libitum to ram groups and water and mineral licks were freely available. Body weight and feed intake was recorded weekly, and semen characteristics were determined every 2 weeks. Dietary treatment affected final body weight (P < 0.01) as feeding level increased. Total dry matter and protein intake changed significantly (P < 0.05 and P < 0.01, respectively) among experimental groups. Semen volume and concentration were positively influenced by feeding level for HC group, whereas no differences were observed in sperm viability and scrotal circumference of rams. It was concluded that dietary level with higher concentrate supplementation resulted in improved body weight gain, feed intake, sperm production, and semen quality in Sardinian rams.     

Abnormalities of the Testes and Epididymis in Bucks and Rams Slaughtered at Debre Zeit Abattoir,Ethiopia

A study was conducted at Debre Zeit export abattoir on 404 bucks belonging to four breeds and 167 rams of two breeds. The animals were selected from the slaughter flock using stratified sampling based on breed. Ante-mortem and post-mortem examinations were carried out after each animal was carefully identified. Various genital abnormalities were observed, among which testicular atrophy and epididymitis were the predominant genital problems in both bucks and rams. The prevalence of cryptorchidism was higher (p<0.05) in bucks than in rams, while epididymitis (p<0.05), sperm granuloma (p<0.01) and epididymal cysts (p<0.05) were more frequent in rams. In bucks, none of these abnormalities was significantly associated with age (p>0.05). However, testicular atrophy (p<0.01), epididymitis (p<0.01) and haemorrhagic lesions (p<0.05) were associated with breed, the prevalence being higher in Woito-Guji and Boran bucks than in the Arsi-Bale and Afar breeds. In rams, age affected (p<0.05) the incidence of testicular atrophy, epididymitis and sperm granulomas. Epididymitis, sperm granuloma and epididymal cysts were more frequent (p<0.01) in Adal rams than in Black Head Somalis.     

Extenders modify the seminal plasma ability to minimize freeze‐thaw damage on ram sperm

Seminal plasma (SP) proteins interact with sperm plasma membrane (PM) modulating its functionality. It has been shown that SP proteins can reverse the damage caused by freeze‐thaw; however in these studies, SP has been added to washed sperm (i.e., cells depleted from homologous SP and extender). The aim of the current study was to assess whether the egg yolk‐based extender (EY) modifies SP ability to ameliorate sperm parameters in frozen‐thawed ram spermatozoa. Ejaculates were diluted in EY or soybean lecithin‐based extender (SL) and evaluated before and after freezing to measure the cell damage according to the extender. Even when all classical parameters decreased after freezing, as expected (p < .05), there was no effect of the extender. SP treatment was applied after freeze‐thaw. Sperm were incubated with SP (20% v/v) in the presence of either EY or SL, and sperm parameters were assessed after thawing compared with the same treatments after Percoll sperm selection (washed). Treatments with 20% SP improved sperm total and progressive motility compared with controls regardless of washing and extender (p < .05); however, washed sperm showed higher percentage of total sperm motility compared with those unwashed (p < .05). Moreover, treatment with 20% SP showed significantly higher percentages of PM integrity, sperm with intact acrosomes, integrity of chromatin and non‐capacitated sperm in samples diluted with EY when washed before treatment compared with the other conditions (p < .05). It was concluded that the presence of the extenders and particularly egg yolk alters the SP capacity to reduce the cryodamage.     

Electroejaculation Increases Low Molecular Weight Proteins in Seminal Plasma Modifying Sperm Quality in Corriedale Rams

This study was conducted to evaluate the effect of seminal collection method (artificial vagina or electroejaculation) on the protein composition of seminal plasma and sperm quality parameters in Corriedale rams. To address this question, we assessed the effect of seminal collection method on motility, plasma membrane integrity and functionality, mitochondrial functionality and the decondensation state of nuclear chromatin in sperm cells. Volume, pH, osmolarity, protein concentration, total protein content and protein profile using sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE) and 2‐D polyacrylamide electrophoresis of seminal plasma collected with artificial vagina and electroejaculation were also analysed. The main findings from this study were that ejaculates obtained with electroejaculation had (i) a higher number of spermatozoa with intact plasma membrane and functional mitochondria and (ii) a higher proportion of seminal plasma, total protein content and relative abundance of low molecular weight proteins than ejaculates obtained with artificial vagina. Five of these proteins were identified by mass spectrometry: binder of sperm 5 precursor; RSVP14; RSVP22; epididymal secretory protein E1 and clusterin. One protein spot with molecular weight of approximately 31 kDa and isoelectric point of 4.8 was only found in the seminal plasma from electroejaculation.     

The relationship between acrosome reaction and polyunsaturated fatty acid composition in boar sperm

This study investigated the relationship between acrosome reactions and fatty acid composition with respect to fertility in boar sperm. The acrosome reaction was induced more than 85% by 60 mM methyl-beta-cyclodextrin (MBCD), and plasma membrane integrity was significantly reduced dependent on the MBCD level in boar sperm (p < .05). The acrosome-reacted sperm exhibited significantly higher saturated fatty acids (SFAs) and lower polyunsaturated fatty acids (PUFAs) composition compared to the non-acrosome reaction group (p < .0001). In addition, the PUFAs, C22:5n-6 (docosapentaenoic acid [DPA]; p < .01) and C22:6n-3 (docosahexaenoic acid [DHA]; p < .0001) were significantly decreased, and cleavage and blastocyst formation of oocytes were significantly (p < .0001) decreased in acrosome-reacted sperm relative to non-acrosome-reacted sperm. Moreover, acrosome reaction was positively correlated with SFAs, whereas negatively correlated with PUFAs, of the PUFAs, the DPA (p = .0005) and DHA (p = <.0001) were negatively correlated with the acrosome reaction. Therefore, these results suggest that the PUFAs composition of sperm is closely involved in acrosome reaction in pigs.     

An In Vitro Evaluation of Biochemical Processes Involved in Lead‐Induced Changes on Ram Spermatozoa

Lead (Pb²⁺) is a toxic heavy metal which interferes with several physiological processes regulated by Ca²⁺, including those characterized by changes of the membrane stability and the motility of spermatozoa necessary for the fertilization of the oocyte. In this study, ejaculated sperm from six rams (Ovis aries) have been incubated in vitro with or without 50 ng Pb²⁺/ml during 30 min and in the presence or absence of three different potential modulators of the effects of Pb²⁺ on changes in the sperm membrane before fertilization: charybdotoxin, quinacrine and staurosporine. Sperm samples incubated with Pb²⁺ have shown significant reductions in acrosome integrity and sperm viability and an increase in progressive movement. None of the studied potential modulators had a protective effect against Pb²⁺ action. On the contrary, Pb²⁺‐incubated sperm in the presence of staurosporine had lower acrosome integrity, and lower sperm viability was observed when spermatozoa were incubated with Pb²⁺ + charybdotoxin. Quinacrine was the only tested substance capable of increasing the concentration of Pb²⁺ in spermatozoa; thus, the enhancement of Pb²⁺ effects produced by staurosporine and charybdotoxin was not produced by an increased uptake of Pb²⁺ by spermatozoa. However, the increase of intracellular Pb²⁺ in those spermatozoa incubated with quinacrine did not result in an adverse effect on sperm motility or viability although the acrosome integrity was negatively affected.     

The association of the presence of seminal plasma and its components with sperm longevity in fractionated stallion ejaculates

Semen jets in the stallion's ejaculate differ in both the biochemical composition of seminal plasma (SP) and in sperm concentration, forming sperm-rich fractions (HIGH) and sperm-poor fractions (LOW). This study examined (i) the association of the levels of selected components of SP [alkaline phosphatase (AP), acid phosphatase (ACP), Na(+), Cl(-), K(+), Ca, Mg and prostaglandin E(2)] with semen quality, sperm longevity and fertility; (ii) the effects of the presence of SP on sperm survival during cooled storage; (iii) the differences in the composition of SP between sperm-rich and sperm-poor ejaculatory fractions; (iv) the differences between these fractions in the effects of SP on sperm longevity. The levels of AP, ACP and Na(+) were higher in HIGH compared with LOW, whereas higher concentrations of Ca, K(+) and Mg were found in LOW than in HIGH. None of the measured components were correlated to the first cycle pregnancy rate. The presence of SP during cooled storage caused DNA degradation, but total and progressive sperm motility was not affected. Sperm-rich fractions stored with low levels of SP maintained higher level of DNA integrity compared with sperm-rich fractions in higher levels of SP, or sperm-poor fractions irrespective of the proportion of SP. The concentration of K(+) in LOW may give some indication on the maintenance of total sperm motility during cooled storage.