Effect of Semen Collection Methods on the Quality of Pre‐ and Post‐thawed Bali Cattle (Bos javanicus) Spermatozoa

This study was conducted to evaluate the response of Bali bulls (Bos javanicus) to different semen collection methods and their effects on fresh and post‐thawed semen quality. The collection methods employed were electro‐ejaculation (EE), transrectal massage (RM) and RM followed by EE (RM + EE). A total of 25 untrained Bali bulls (age between 2 and 4 years old) were subjected to the different semen collection methods. Fresh semen samples from all the 25 bulls were evaluated for volume, pH, general motility, live/dead ratio and abnormality using the conventional method. For fresh and frozen samples collected by EE and RM from 10 bulls, computer‐assisted semen analysis system was used for precise quantitative measurement of motility, velocity and forward progression. Accucell photometer was used to measure sperm concentration in all samples, regardless fresh and frozen. Semen samples were obtained 100% of the attempts using EE, 84% using RM and 96% using RM + EE. There were no differences among the collection methods for fresh semen quality characteristics, including motility, morphology and viability, but pH and volume were higher for EE than RM and RM + EE. Higher sperm concentration was observed in semen collected by RM than the other two methods. Different age groups (2–3 and >3–4 years old) of the bulls did not show significant differences in volume, pH, sperm concentration, percentages in motility, live/dead ratio and normal sperm morphology. The quality of semen for general and progressive motility, VAP, VSL and VCL and acrosomal integrity after thawing was higher for RM than EE. In conclusion, Bali bulls appeared to respond best to EE and the combination of RM + EE than RM, as a method of semen collection, with a shorter time of stimulation required. Differences in age of the Bali bulls did not affect the semen quality.     

Effects of supplemental conjugated linoleic acids (CLA) on fresh and post‐thaw sperm quality of Holstein bulls

This study was designed to investigate the effects of feeding‐protected conjugated linoleic acid (CLA) on the semen production and sperm freezability in Holstein bulls. Twelve bulls were randomly assigned to two groups (n = 6 per group). Bulls received the normal diet (control group) or the normal diet top‐dressed with 50 g of CLA (treated group) for 10 weeks. The control group received 40 g/day calcium soap of fatty acid. Fresh and post‐thaw semen quality was assessed on ejaculates collected at the 0, 4, 6, 8 and 10 week of supplementation. Semen evaluations including sperm concentration, motion characteristics (subjective and computer‐assisted), viability (Eosin–Nigrosin), membrane integrity (hypo‐osmotic swelling test) and abnormality were conducted. Semen volume, sperm concentration and total sperm output were not affected by dietary treatment (p > .05). The proportion of spermatozoa with abnormal morphology in fresh semen significantly increased (p < .05) in the CLA‐fed group compared to control group. Also, in CLA‐fed group, the proportion of post‐thaw spermatozoa with abnormal morphology at week 10 of trial was significantly higher in CLA than control group (p < .05). Progressive motility tended to be increased in the CLA‐fed group, although dietary supplementation did not affect other CASA parameters or viability in fresh and frozen‐thawed sperm. In this study, CLA supplementation had little positive effect on fresh or post‐thaw sperm quality of Holstein bulls.     

Variation in sperm cryosurvival is not modified by replacing the cryoprotectant glycerol with ethylene glycol in bulls

Breed and sire differences in sperm cryosurvival have been noted, with negative implications for sperm cryobanking and assisted reproduction programmes. This study hypothesized that these differences could be modified by using lower molecular weight cryoprotectants. Therefore, the effect of replacing glycerol (GLY) with ethylene glycol (EG) on differential cryosurvival of semen from two Sanga cattle breeds (Mashona vs. Tuli) was determined. Three to five ejaculates were collected from each of ten bulls (3-8 years) by electro-ejaculation, diluted in three Tris-egg yolk extenders (Triladyl^®, 7% GLY-based and 7% EG-based) and evaluated for sperm motility, viability and morphology at three time periods (fresh – 0 hr, pre-freeze – 4 hr and post-thaw). Tuli bulls produced larger (11.8 ± 0.31 ml vs. 8.5 ± 0.38 ml) and more concentrated ejaculates of lower fresh semen quality. Breeds differed across time for motility and morphology, but not viability. Mashona bull semen had significantly higher motility and normal morphology values at each sampling time. Bulls classified as poor freezers had lower concentration (0.70 ± 0.09 × 10⁹ sperm/ml vs. 1.37 ± 0.10 × 10⁹ sperm/ml), sperm motility index (SMI, 35.0 ± 3.4 % vs. 67.8 ± 2.1 %) and viability (69.7 ± 1.1 % vs. 75.7 ± 1.0 %) compared to good freezers. Maintenance of semen quality by GLY and EG did not differ between breeds, poor and good freezers, or age groups. The interaction breed by extender across time did not reach statistical significance for all variables. The study revealed that bull and breed variation in sperm quality and cryosurvival is not modified by replacing GLY with EG, suggesting that cryostress tolerance of sperm may be under control of mechanisms other than differential response to GLY cytotoxicity.     

Melatonin supplementation improved cryopreserved Thai swamp buffalo semen

The production of reactive oxygen species (ROS) during cryopreservation process impairs the sperm characteristics and fertilizing ability. However, melatonin, an antioxidant, could protect spermatozoa against this cell damage during cryopreservation. Therefore, we attempted to evaluate whether the melatonin supplementing in the semen extender could improve the sperm quality of swamp buffalo during cryopreservation. The semen collected from six swamp buffalo bulls were diluted with tris-citrate egg yolk extender supplementing with 0, 0.1, 0.5, 1.0, 2.0 and 3.0 mM of melatonin. The parameters of sperm viability and motility were evaluated using computer-assisted semen analyser (CASA) after cryopreservation on days 1, 7, 15 and 30. The group supplemented with 1.0 mM melatonin exhibited the higher viability after cryopreservation on days 1, 7, 15 and 30 with 58.346 ± 2.1^a, 57.586 ± 2.0^a, 55.082 ± 1.8^a and 55.714 ± 1.8^a, respectively, and showed the best results of motility parameters. However, higher concentration of melatonin at 3.0 mM impaired all the parameters. In conclusion, the addition of melatonin at 1 mM to semen extender could exert the best protection against sperm damage in swamp buffalo bull during cryopreservation.     

The Effect of Trehalose Supplementation of INRA-82 Extender on Quality and Fertility of Cooled and Frozen-Thawed Stallion Spermatozoa

Stallion semen cryopreservation is often associated with poor post-thaw sperm quality. Sugars act as nonpermeating cryoprotectants. The aim of the present study was to evaluate the cryoprotective effect of trehalose on stallion sperm quality and field fertility rates subjected to cooling and freeze–thaw process. Semen samples were collected from six Arabian stallions, divided into five different treatments in a final concentration of 100 × 10⁶ sperm/mL by using INRA-82 extender containing 0, 25, 50, 100, and 200 mM of trehalose then subjected to both cold storage and cryopreservation. Sperm motility, acrosome, plasmatic membrane, and DNA integrity were analyzed, and 57 mares were used to evaluate the field fertility of chilled and frozen-thawed semen. Results showed that the extender containing 100 mM trehalose only increased the functional acrosomal, plasma membrane, and DNA integrities. The inclusion of 50 mM trehalose in semen extender resulted in significantly (P < .05) increased post-thaw total motility compared to the control group, and chilled semen achieved higher pregnancy rates compared to the frozen-thawed one. Pregnancy rate of mares inseminated with frozen-thawed semen (P < .05; 46.15% vs. 36.36%, respectively) was lower than those inseminated with chilled semen (76.47% vs. 68.75%, respectively) but higher than control. In conclusion, addition of 50 mM trehalose yielded the highest quality stallion semen after cooling and post-thawing in terms of motility, integrities of acrosome, membrane, and DNA as well as improved field fertility.     

广州地区娟姗公牛与荷斯坦公牛精液品质的比较研究

本试验选择亚热带气候条件下广州地区的娟姗公牛和荷斯坦公牛各5头,比较两个品种公牛的精液品质(采精量、原精密度、原精活力、细管精液产量、冻后活力、低渗膨胀率及穿透率)。研究表明,荷斯坦公牛每次采精的采精量(16.14±0.06 mL)和细管精液产量(189.17±3.11支)都极显著地高于娟姗公牛(4.74±0.05 mL,158.46±2.64支)(P<0.01);娟姗公牛的原精密度(8.95±0.08亿/mL)极显著地高于荷斯坦公牛(8.32±0.07亿/mL;P<0.01);娟姗公牛原精活力(0.731±0.004)高于荷斯坦公牛(0.729±0.003),但两者差异不显著(P<0.05);娟姗公牛精液的冻后活力(0.355±0.003)极显著高于荷斯坦公牛(0.339±0.003;P<0.01);娟姗公牛冷冻精液的低渗膨胀率(34.50%±0.49%)显著高于荷斯坦公牛(31.21%±0.59%;P<0.01);娟姗公牛冷冻精液对去透明带仓鼠卵的穿透率(84.51%±13.83%)显著高于荷斯坦公牛(81.52%±6.13%;P<0.05)。     

Serum kisspeptin: New possible biomarker for sexual behaviour and sperm concentration in buffalo bulls

The study was designed to decipher the inter-relationship between peripheral hormones (kisspeptin and testosterone), sexual behaviour and seminal variables of Murrah buffalo bulls (n = 134). In this study, we recorded that 13%, 37%, 40%, 6% and 4% Murrah buffalo bulls had reaction time of <30, 31–60, 61–180, 181–300 and >300 s, respectively. Further, it was observed that 4%, 85% and 10% buffalo bulls were sexually aggressive, active and dull, respectively, during semen collection. The courtship behaviour was not found to be desirable for the bulls used for the semen collection. Mean of ejaculate volume, sperm concentration and mass motility (0–5 scale) were 3.57 ml, 977.11 million/ml, 2.7, respectively. Correlation studies revealed that the reaction time was positively correlated with courtship behaviour and body weight, and negatively correlated with sexual aggressiveness and sperm concentration. Serum kisspeptin in buffalo bulls, measured for the first time, was found to 3.8 ± 0.7 ng/ml. Serum kisspeptin and testosterone level are negatively correlated to each other and kisspeptin level influenced the sexual behaviour (reaction time, sexual aggressiveness and penile erection) of study bulls. Serum kisspeptin was higher in the buffalo bulls with higher sperm concentration indicating its role in spermatogenesis. In conclusion, for the first time basic information related to sexual behaviour of Murrah buffalo bulls in large population along with its inter-relationship with peripheral hormones (kisspeptin and testosterone) has been documented.     

Effect of organic and inorganic selenium supplementation on semen quality and blood enzymes in buffalo bulls

The present study aimed to evaluate the effect of organic and inorganic selenium (Se) supplementation on semen quality and blood serum profiles of buffalo bulls. Nine mature buffalo bulls were divided into three groups: control (non‐supplemented); organic Se (10 mg Sel‐Plex®/head twice weekly) and inorganic Se (10 mg sodium selenite/head twice weekly). Semen was collected twice a week for 3 months during Se supplementation. Semen properties were evaluated from fresh ejaculate. Moreover, fructose concentration, aspartate and alanine transaminase (AST and ALT) activities, total protein and total cholesterol were assayed in seminal plasma. Additionally AST, ALT, testosterone and Se levels were determined in the blood serum. Results showed that Se supplementation significantly (P < 0.05) influences the semen parameters during 3 months of treatment. Organic Se significantly (P < 0.05) increased the percentage of viable sperms compared to inorganic Se and the control group. Fructose concentration was significantly higher (P < 0.05) in the seminal plasma of organic Se‐treated bulls. Serum testosterone and Se concentrations were significantly (P < 0.05) increased in the Se supplemented groups than the control group. In conclusion, Se supplementation improved the parameters of buffalo bull semen and more precisely, organic Se was more effective for the improvement of semen quality and some blood components than inorganic Se.     

Relationship of age to body weight,scrotal circumference,testicular ultrasonograms,and semen quality in Sahiwal bulls

The objective of the present study was to determine the relationship of age to body weight (BW), scrotal circumference (SC), number of pixels of testicular ultrasonograms (NP), and semen quality in Sahiwal bulls. The study was based on 128 Sahiwal bulls of different age groups (from 0 to >100 months of age). Bulls were evaluated for SC, BW, and NP. Semen was evaluated once a week for five consecutive weeks from regularly collected donor bulls (n = 86) ranging in age from 25–30 to >100 months. Ejaculate volume, sperm motility, sperm concentration, sperm morphology, percent live sperms, sperm plasma membrane integrity, and normal acrosome were compared among different age groups. Mean SC and BW increased (P < 0.05) in a curvilinear manner from birth to >100 months of age. Mean NP of testicular ultrasonograms increased (P < 0.05) from 0 to 24 months and then plateaued until >100 months of age. Body weight, SC, and NP were positively correlated with age from birth until >100 months (r = 0.91, 0.87, and 0.40, respectively). Ejaculate volume (5.7 ± 0.2 vs. 4.6 ± 0.09 ml) and sperm concentration (1,281.6 ± 17.7 vs. 1,115.8 ± 55.9 × 10⁶/ml) increased (P < 0.05) in mature bulls compared to younger ones. However, motility (68.6 ± 0.3%), plasma membrane integrity (50.8 ± 1.0%), and normal acrosome (74.8 ± 0.5%) remained insignificant due to age. In six of eight age groups studied, morphological abnormalities were well within the range (18.1 ± 0.3%). In conclusion, the BW, SC, and NP of testicular ultrasonograms, ejaculate volume, and concentration increased with age. Moreover, semen quality is fairly independent of age except volume and concentration in Sahiwal bulls.     

Effect of age and season on semen quality parameters in Sahiwal bulls

The objective of the study was to determine the effect of season, period, age, bull, and ejaculate on semen quality in Sahiwal bulls. Semen production records from 1996 to 2006 of 5,483 ejaculates from 46 Sahiwal bulls maintained at Artificial Breeding Complex, NDRI, Karnal, India were analyzed using least square analysis of variance by LSML software package. The overall least squares means of ejaculate volume (VOL), total volume per day (VOLD), mass activity (MA), initial motility (IM), sperm concentration per ml (SPC), and sperm concentration per ejaculate (SPCE) were 3.79 ± 0.02 ml, 5.81 ± 0.06 ml, 2.32 ± 0.01, 55.47 ± 0.001%, 766.69 ± 5.50 × 10⁶/ml and 3023.25 ± 30.15 × 10⁶, respectively. All semen traits (VOL, VOLD, MA, IM and SPCE) were significantly (P < 0.01) affected by age groups, season and period, whereas season had significant effect on VOL at 5% level. During hot-humid season, highest value of VOL, VOLD, MA, IM, SPC, and SPCE were observed followed by summer and cold season. Highest value of VOL, VOLD, IM, and SPCE were observed during period-3 (2004–2006), whereas highest value of MA and SPC were observed during period-1 (1996–1999). However, lowest magnitude of MA, IM, SPC, and SPCE during period-2 (2000–2003) was observed. Ejaculate characteristics like VOL, VOLD, and SPCE increased with the increasing age of bull up to 5 years and then decreased. Significant (P < 0.01) bull to bull variation was found in VOL, VOLD, MA, IM, SPC, and SPCE traits. First ejaculate had significantly (P < 0.01) higher MA, IM, SPC, and SPCE. Hence, it could be concluded that during rainy season and period-1 and period-3 the quality of semen is quantitatively and qualitatively good. Better quality semen was obtained up to 5 years of age in Sahiwal bulls.     

Effects of supplemental dietary vitamin C on quality of semen from Nile tilapia (Oreochromis niloticus) breeders

The objective of this study was to evaluate the effects of vitamin C on growth and quality of semen from Oreochromis niloticus breeders. One hundred and sixty males were fed with different levels of vitamin C (0, 261, 599 and 942 mg/kg diet). The higher weight values were recorded for 599 (166 g) and 942 (175 g) mg of vitamin C/kg diet. Sperm motility, vigour and concentration were higher with 599 and 942 mg of vitamin C/kg diet. The semen volume, gonadosomatic index and plasma protein data from the last week showed a direct relationship with increasing levels of vitamin C. No changes were observed in the hepatosomatic index and blood glucose. The haematocrit and erythrocyte showed higher values estimated by equations derived at 850 and 638 mg vitamin C/kg diet, respectively. The leucocytes were inversely proportional to the increasing levels of vitamin C. After 100 days of feeding, animals fed the diet containing 942 mg vitamin C/kg diet had higher sperm motility, linearity, curvilinear velocity, straight line velocity and average path velocity (p < .05). Higher values of beat cross‐frequency were observed in broodfish fed diets containing 942 and 599 mg vitamin C/kg. The different vitamin C levels did not cause differences in straightness, lateral head displacement and sperm morphology. For Nile tilapia males on intensive rearing and handling conditions, vitamin C levels between 599 and 942 mg/kg may be used for a better performance and quality of semen.     

Effect of cattle-specific estrus molecules on libido and semen production of zebu bulls under tropical climate

Zebu bulls are a shy breeder and they exhibit optimum libido in the presence of females with estrus phase. Continuous semen collection with the use of male dummy leads to lack of adequate sexual stimulation. Therefore, the present study was designed to test the effect of estrus-specific molecule(s) for effective sexual preparation of donor bulls. The bulls were divided into normal and poor libido group, five bulls in each group by taking 1-month control study data after collecting the information of individual bull’s sexual behaviour during semen collection by regular semen collector. The bulls were never being exposed to female animals and semen was collected by an artificial vagina. The ten animals were exposed to a glycerol-water solution (50/50 v:v) as control and then exposed to estrus-specific molecules one by one. The estrus-specific molecules like squalene, 1-iodoundecane, acetic acid, coumarin, propionic acid, oleic acid, and 2-butanone were purchased from Sigma-Aldrich Company, USA, and the molecules were solubilised individually in a non-pressurised aerosol dispenser as 1.0% concentration in glycerol-water solution (50/50, v:v). Identical bulls were used as the control and exposed to each molecule one by one by giving a refractory period of 14 days. A nasal spray of acetic acid or 2-butanone significantly (p < 0.05) reduced reaction time (RT) and total time taken to ejaculate (TTTE) in normal libido bull group. Semen volume, sperm concentration, and the total number of sperm per ejaculation obtained did not show significant improvement in the normal libido group of bulls after the application of estrus-specific molecules as compared to the control. In poor libido group, acetic acid, oleic acid, and 2-butanone application showed significant (p < 0.01) improvement in RT and TTTE as compared to the control group, whereas semen production variables like sperm concentration and total sperm output per ejaculation increased significantly (p < 0.05) except semen volume. There was significant (p < 0.01) reduction in RT (%) and TTTE (%) after the application of acetic acid followed by 2-butanone and oleic acid. The sperm concentration and total sperm output per ejaculation were more after the application of each molecule but significant increase (p < 0.05) in sperm concentration was observed with 2-butanone (11.42%), acetic acid (11.42%), and oleic acid (10.13%), whereas total sperm output per ejaculation increased significantly (p < 0.05) only after the application of acetic acid and 2-butanone (24.75% and 26.84%). Hence, it can be concluded that acetic acid, 2-butanone, and oleic acid are effective for better sexual preparation of Sahiwal bulls and total sperm output per ejaculation.

     

夏南牛与夏洛来公牛精液品质的对比分析研究

[目的]通过比较夏南牛和法系夏洛来的精液品质,探索中原地区肉牛改良的适合品种。[方法]选择中原地区的夏南牛和法系夏洛来种公牛各5头,比较两个品种种公牛的精液品质（采精量、原精密度、原精活力、细管产量、冻后活力、精子畸形率）。[结果]表明：夏南牛公牛精液品质极显著的高于夏洛来牛。[结论]夏南牛公牛更适应中原地区的气候条件...     

发情母牛粘液对采精公牛交配能力及精液品质影响的研究

[目的]研究发情母牛粘液对采精种公牛交配能力以及精液品质的影响。[方法]从采精种公牛中随机抽出10头,进行2次采精试验,第一次按照正常方法采精,第二次在台牛尾根附近涂抹粘液,记录交配能力,将2次采精所采得的精液进行检测。[结果]第二次采精交配能力明显高于第一次。精液量、精液密度、活率、有效精子数、冻后活率、生产冻精数分别为：5.76 mL、19.23亿/mL、0.72、13.4、0.385、400.5,通过T检验P〈0.01,差异显著。[结论]在台牛后躯涂抹发情母牛粘液刺激公牛使交配能力和精液品质显著提高。     

Factors affecting breeding soundness classification of beef bulls examined at the Western College of Veterinary Medicine

Breeding soundness evaluation records from 2110 beef bulls, for the period of 1986 to 1999, were analyzed to determine the prevalence and importance of factors affecting breeding soundness classification. The percentage of all bulls classified as satisfactory ranged from 49.0% in January to 73.3% in May. The percentage of physically normal bulls with satisfactory semen quality ranged from 65.7% in January to 87.5% in June. Poor body condition or excessive body condition, below average or below the recommended minimum scrotal circumference, lameness, and severe scrotal frostbite significantly reduced the probability of a satisfactory breeding soundness classification. The percentage of sperm with midpiece defects declined significantly and the percentage of sperm with head defects increased significantly with the approach of summer. Photoperiod, cold stress, poor or excessive body condition, and reduced feed quality may interact to reduce semen quality in the winter months.     

In vivo adverse effects of alpha‐tocopherol on the semen quality of male bucks

Oxidative stress has detrimental effects on semen quality during spermatogenesis and semen processing for artificial insemination. This work was conducted to study the effect of different levels of vitamin E on the semen traits, oxidative status and trace minerals in Beetal bucks. Thirty‐six bucks of similar body weight and age (1 year) were randomly divided into four groups. One group was kept as control with no supplementation (group 1), and the others were supplemented with 200 (group 2), 400 (group 3) and 800 IU (group 4) vitamin E/animal/day for 2 months. At the end of the experiment, semen samples were collected and evaluated. Seminal plasma was separated to study the concentration of superoxide dismutase (SOD), glutathione peroxidase (GPx), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and trace minerals (Zn, Cu, Mn and Fe). Group 3 showed significantly higher (p < 0.05) semen volume and per cent motility and lower dead sperm percentage compared to control group. Superoxide dismutase, GPx, Zn, Cu and Mn were higher in the same group. The level of AST decreased in group 3 without any change on the concentration of ALT. It is suggested that vitamin E at the rate of 400 IU/buck/day supported higher semen volume, per cent motility, per cent live spermatozoa, antioxidants (SOD, GPx) and trace mineral levels (Zn, Cu, Mn) in the seminal plasma. The increased supplementation from 0 to 400 showed a general increasing trend in improving semen quality. However, the dose of 800 IU/kg had no useful effect in further improving the semen quality.     

The Effect of Sperm Morphology and Sire Fertility on Calving Rate of Finnish Ayrshire AI Bulls

Good‐quality semen is a prerequisite for successful and profitable artificial insemination (AI) of modern dairy cattle. Fertility of the bulls is evaluated with andrological examinations and semen analyses, such as morphology. However, little attention has been paid to the inheritance of bull fertility. In this study, we correlated sperm morphology, birth year and station of 695 AI bulls with calving rate (CR). Sperm morphology was clearly associated with CR underlining the usefulness of morphological examination in the assessment of fertility. The correlation between the proportion of normal spermatozoa and CR was significant (p < 0.001). No significant differences were detected between stations or birth years. We also compared the CR of 695 AI bulls with the CR of their 27 sires to study the inheritance of fertility. Sire's CR did not correlate with the CR of the sons (p = 0.218). This result indicates that at least when sires of acceptable CR are used to produce sons for use in AI the inheritance of CR is not significantly correlated.     

The Effect of Season on Semen Characteristics and Freezability in Bos indicus and Bos taurus Bulls in the Southeastern Region of Brazil

The objectives of this study were to evaluate the effects of season in southeast of Brazil comparing genotypes on semen characteristics, freezability and peripheral plasma concentrations of testosterone. Ejaculates of five Bos indicus bulls and six Bos taurus bulls were evaluated over a period of 27 months, which was divided into winter (July, August, September), spring (October, November, December), summer (January, February, March) and autumn (April, May, June). Semen was evaluated according to standard procedures for ejaculate volume, sperm concentration, gross-motility, progressive motility and sperm morphology. After preparing and freezing the ejaculates according to commercial procedures, the straws were stored in liquid N₂ until post-thaw evaluation. Ejaculate volume, sperm concentration, gross-motility, progressive sperm motility, vigor and morphological sperm defects were significantly influenced by season and genotype (p < 0.05). Heat tolerance was better in B. indicus bulls than in B. taurus bulls characterized by lower values of sperm abnormalities throughout the observation period. The highest values were recorded for abnormal heads followed by cytoplasmatic droplets in B. taurus bulls. The proportion of ejaculates which were eliminated before freezing for reasons of bad quality was lower in the B. indicus bulls. Temporal changes in peripheral plasma testosterone concentrations were higher in B. indicus bulls than in B. taurus bulls not revealing seasonal influences. The results of this study show clear genotype differences regarding semen quality. Freezability of B. taurus semen varies considerably throughout the year, leading to a high proportion of eliminated ejaculates. Collecting semen from B. taurus bulls during the summer in an artificial insemination centre may not be profitable.     

In vitro studies of Norwegian Red bovine semen immobilized and cryopreserved in alginate solid gel network

Development of new semen cryopreservation techniques improving sperm survival and ensuring availability of viable spermatozoa for a prolonged time‐period after AI is promising tools to reduce sensitivity of timing of AI and enhance overall fertility. The SpermVital^® technology utilizes immobilization of bull spermatozoa in a solid network of alginate gel prior to freezing, which will provide a gradual release of spermatozoa after AI. The objective of this study was to compare post‐thaw sperm quality and in vitro sperm survival over time of Norwegian Red bull semen processed by the SpermVital^® (SV) technology, the first commercialized production line of SpermVital^® (C) and by conventional procedure applying Biladyl^® extender (B). Post‐thaw sperm motility was not significantly different between SV, C and B semen (p > .05). However, sperm viability and acrosome intactness were higher for SV than C and B semen (p < .05). Small differences in DNA quality were observed (p < .05). Sperm viability after storage in uterus ex vivo was higher for SV than for C semen (p < .05). Furthermore, sperm survival in vitro over time at physiological temperature was significantly higher for SV semen than C semen as well as B semen during the incubation period of 48 hr (p < .05). In conclusion, the SpermVital^® technology is improved and is more efficient in conserving post‐thaw sperm quality and results in higher sperm viability over time in vitro for SV than for C and B semen.     

Effects of reduced glutathione supplementation in semen freezing extender on frozen-thawed bull semen and in vitro fertilization

During cryopreservation, spermatozoa may suffer cold and cryo-induced injuries ―associated with alterations in cell defense systems― that are detrimental to their function and subsequent fertility. This study aimed to determine the efficacy of supplementing the semen freezing extender with the antioxidant reduced glutathione (GSH) in cattle. Semen was collected from four bulls and diluted in a freezing extender supplemented with or without GSH (0, 1, 5, and 10 mM) before the cooling step of the cryopreservation process. After thawing, the quality of the frozen-thawed semen was investigated for motility, viability, acrosomal and DNA integrity, and subsequent embryo development after in vitro fertilization of bovine oocytes. Additionally, semen from one of the bulls was used to analyze semen antioxidative potential, sperm penetration into oocytes, male pronucleus formation rate, and embryo DNA integrity. The sperm quality varied among bulls after GSH supplementation. One bull had decreased sperm total motility, and two bulls had decreased sperm DNA integrity. GSH supplementation had positive effects on embryo development for three bulls. Two of them showed both improved cleavage and blastocyst formation rates, while the other one only showed an improved cleavage rate. We observed positive effects on early male pronucleus formation and no negative effects on DNA integrity and cell number in blastocyst stage embryos. Although the effect varies depending on individual bulls and GSH concentration, GSH supplementation in semen may improve in vitro embryo production from frozen semen.