Spermatogenic activities of the left and right testes of hemicastrated and intact cockerels

One hundred cockerels of the Hacco strain were reared in deep litter. At 5 weeks of age the left testes of 30 cockerels and right testes of another 30 cockerels were surgically removed. The remaining cockerels were sham operated. At 10, 15, 20 and 25 weeks of age equal numbers from each group were killed. The rate of testis growth, the spermatid/spermatozoa reserve for each genital tract, and the relative spermatogenic activity (i.e., spermatid/sperm per g of testicular tissue) were determined for the left and right testes at the different ages.At 10 weeks of age only spermatids were found in all the testes, with concomitant very low relative spermatogenic activities. The weights of the testes increased with age and compensatory hypertrophy occurred in the testes of the hemicastrates from 15 weeks of age. The mean of the sperm reserve of the left (7.391 × 10⁹ sperm) and right (8.66 × 10⁹ sperm) genital tracts of hemicastrates contained significantly more (P < 0.05) sperm than the sum of the means of the sperm reserves in the left and right genital tracts (5.19 × 10⁹sperm) of the intact cockerels at 25 weeks of age.The relative spermatogenic activities varied with age but the pattern was similar for all cockerels, with the activities of the testes of the hemicastrates being significantly higher (P < 0.5). In all cases the values for the right testes were higher than those for the corresponding left testes.At 15 weeks of age both spermatids and spermatozoa were found in 71.4% and 100% of the right and left testes of the hemicastrates, respectively, and in 25% of the left testes of the intact cockerels. Only spermatids were found in the right testes of the intact cockerels.Hemicastration caused the right testes of the hemicastrates to produce sperm earlier than those of intact cockerels. The left testes in all cases produced sperm earlier than the corresponding right testes. Hemicastration enhanced sperm numbers per g testes (i.e., relative spermatogenic activity).     

Spermatogenesis, sperm output and seminal quality of Holstein bulls electroejaculated after administration of oxytocin

The 12- to 24-month-old Holstein bulls were electroejaculated twice on each of 3 days per week throughout the study. After a 2-week stabilization period and subsequent 2-week pre-treatment period, 7 bulls were given 50 i.u. oxytocin via the jugular vein 10 min before each first ejaculate for 10 weeks. The 7 control bulls were handled identically but did not receive oxytocin. All bulls were castrated at the end of the study. Oxytocin was without effect on spermatogenesis (P greater than 0.10). Oxytocin did not alter the total number of spermatozoa harvested per collection day (P greater than 0.10), but increased the number of spermatozoa in first ejaculates by an average of 34.2% (P less than 0.025). Oxytocin did not affect sperm quality (P greater than 0.10) as judged by the motility of spermatozoa in fresh semen or by the motility or percentage of spermatozoa with intact acrosomes in thawed semen. It is concluded that 50 i.u. oxytocin enhanced sperm output in first ejaculates of electroejaculated bulls without altering daily sperm production or seminal quality.     

Influence of ejaculation frequency of stallions on characteristics of semen and output of spermatozoa.

Approximately 1 week was required to stabilize the extragonadal sperm reserves in stallions ejaculated daily for 10 weeks. The true daily sperm output of a stallion was equal to the mean daily sperm output of seven ejaculates +/- 1-35 X 10(9) spermatozoa. Mean concentrations of spermatozoa/ml and number of spermatozoa/ejaculate were higher (P less than 0-01) for X1 and X3/week ejaculation frequencies than for a X6/week frequency. Sperm output/week was nearly identical for a X6/week frequency. Sperm output/week was nearly identical for the X3 and X6 frequencies and higher (P less than 0-01) than the X1 frequency. Increase of ejaculation frequency from one to two ejaculates/day twice weekly significantly (P less than 0-01) raised the output of spermatozoa/week. Gel-free semen volume, spermatozoa/ml, and number of spermatozoa/ejaculate were higher (P less than 0-01) in the first, than in the second, ejaculate. Collection of semen on alternate days would be a practical ejaculation frequency for inseminating mares. Two ejaculates collected twice a week would be a practical ejaculation frequency for long-term storage of stallion semen.     

Influence of exogenous testosterone on sperm production, seminal quality and libido of stallions.

The effect of exogenous testosterone on sperm production, seminal quality and libido was studied in 24 stallions. Based on pretreatment data, a stallion was assigned to 1 of 3 groups each containing 8 animals. One member of each group received 0 (Group 1), 50 (Group 2), or 200 micrograms (Group 3) testosterone propionate per kg body weight every 2 days for 88 days. The lower dose of testosterone had no significant effect on most of the parameters studied: the higher dose depressed total scrotal width at Day 90 post-treatment (P less than 0.01), total spermatozoa ejaculated between Days 60 and 90 (P less than 0.01) and 96 progressively motile spermatozoa between Days 60 and 90 (P less than 0.10). One half of the stallions from each treatment were castrated on Day 90. In the operated stallions, the mean number of spermatids per g testicular parenchyma in the controls (Group 1) was significantly (P less than 0.05) higher than that in Group 3 whereas the difference between the number of spermatids/testis in the same stallions of these two groups was significant only at P less than 0.1. Testosterone propionate treatment did not influence time to erection, interval from first mount to ejaculation or number of mounts per ejaculation. The treatment of normal, intact stallions with testosterone propionate did not enhance libido and caused a severe depression of reproductive capacity.     

Effects of semen fractionation and dilution ratio on equine spermatozoal motility parameters

Two experiments were conducted to examine the effects of semen fractionation and dilution ratio on motility parameters of stallion spermatozoa. In Experiment 1, three ejaculates from each of three stallions were divided into sperm-rich (SR) and sperm-poor (SP) fractions to determine the difference in sperm concentration. Mean sperm concentration in SR fractions (349.5 x 10(6)/ml) was greater (P < 0.001) than that of SP fractions (96.9 x 10(6)/ml). In Experiment 2, three ejaculates from each of two stallions were divided into SR and SP fractions. Fifty percent of the original volume of SR fractions was combined with 50% of the original volume of SP fractions for each ejaculate to represent total ejaculates. SR and total ejaculates were diluted with skim milk-glucose semen extender as follows: 1) no dilution, or dilution to 2) 100 x 10(6)sperm/ml, 3) 50 x 10(6)sperm/ml, or 4) 25 x 10(6)sperm/ml. Semen samples were evaluated at 0.5, 3, 6, 12, and 24 h postejaculation (25 degrees C storage temperature) for percentages of total spermatozoal motility (TSM) and progressive spermatozoal motility (PSM). Mean TSM was greater (P < 0.05) in SR ejaculates than total ejaculates at 12 and 24 h postejaculation. Mean TSM of undiluted semen was lower (P < 0.05) than other dilution ratios over all periods. Mean TSM was greater (P < 0.05) at a 25 x 10(6)sperm/ml dilution ratio than a 50 x 10(6)sperm/ml dilution ratio at 12 and 24 h postejaculation, and greater (P < 0.05) than a 100 x 10(6)sperm/ml dilution ratio from 3 to 24 h postejaculation. Similar patterns were found for PSM. Collection of SR ejaculates and dilution to 25 x 10(6)sperm/ml improved longevity of spermatozoal motility.     

Collection method, season and individual variation on seminal characteristics in the llama (Lama glama)

The objective of the present study was to evaluate the effect of semen collection method (electroejaculation "EE" as compared with the artificial vagina "AV"), the season (summer versus winter) and the male used on macroscopic and microscopic characteristics of ejaculates in llamas. A total of 110 ejaculates were collected from six males and 92 of them were analyzed. Ejaculate volume, concentration, total sperm and the following sperm characteristics were studied: motility, membrane function (HOS test), membrane integrity (CFDA/PI fluorochromes) and morphology. A mixed linear model, that considered season and collection method as the fixed variables and the male as the random variable, was used for the statistical analysis. Variability was found between males (p相似文献   

Motion characteristics of Murrah buffalo bull spermatozoa in various seasons and its relationship with functional integrity of the plasmallema

Semen was collected from six adult (3.5-7-year-old) Murrah buffalo bulls at weekly intervals for 1 year and evaluated for routine parameters, motion characteristics, reactivity in hypoosmotic solution, and acrosomal and other morphological abnormalities of the spermatozoa. The overall motility (MOT), straight line velocity (VSL), curvilinear velocity (VCL), linearity (LIN), lateral head displacement (ALH) and average path velocity (VAP) were 66.85+/-2.79%, 26.58+/-0.24 and 107.07+/-1.47 microm/s, 26.91+/-0.01%, 11.19+/-0.09 and 61.78+/-2.79 microm/s, respectively. Significant seasonal variation was observed in sperm kinematics and hypoosmotic swelling (HOS) reactivity. Except for LIN, the mean values of sperm dynamics were higher during summer and rainy season and significantly lower in winter season. Sperm kinematics showed significant (P<0.01) positive correlation (r=0.25-0.60) with plasmallemal integrity. Ejaculates with less than 50% HOS-reactive spermatozoa had significantly lowered MOT, VSL, VCL and VAP as compared to the ejaculates with >50% HOS-positive spermatozoa. No significant difference was observed in sperm kinematics among the ejaculates having 50-70% and >70% HOS-reactive spermatozoa. The trend of motion dynamics of the spermatozoa with respect to HOS reactivity was similar in all the three seasons (summer, rainy and winter). The results indicate that ejaculates having more than 50% of HOS-reactive sperm show a higher magnitude of sperm kinematics compared to ejaculates having less than 50% HOS-positive spermatozoa.     

Post-thaw motility and longevity of motility of imipramine-induced ejaculates of pony stallions

Imipramine-induced ex copula ejaculates (11) and fractionated in copula ejaculates were collected from each of 5 pony stallions for freezing in 5-ml straws (6), using a modified Kenney glucose skim-milk extender (2). Initial post-thaw total and progressive motilities and daily post-thaw total and progressive motilities, as well as the number of days to reach 0 progressively motile spermatozoa, were also similar for the 2 methods of collection. The percentage of morphologically normal spermatozoa both before freezing and after thawing were also similar for in copula and ex copula ejaculates. Consistent with previous work (11), imipramine-induced ejaculates were of extremely high sperm concentration and low volume compared with those of in copula ejaculates. In this study, imipramine-induced ejaculates were of significantly higher concentration of sperm and lower volume than fractionated (first 2-3 jets) in copula ejaculates. These results suggest that imipramine-induced ejaculates may be suitable for cryopreservation. Breeding trials are necessary to evaluate actual fertility of semen.     

Quality and freezing qualities of first and second ejaculates collected from endangered Gulf Coast Native rams

The Gulf Coast Native sheep, or Louisiana Native sheep, is an endangered previously feral domestic sheep population of European origin that has been under natural selection pressure for reproductive survival in their transplanted range while roaming in the southern Gulf Coast Region of the United States. This sheep population has an increased natural resistance to internal parasites, breeds year-around and has a greater percentage of live lambs as compared with other breeds of sheep raised in similar environments. To preserve the genetic diversity of this important feral sheep population, semen was collected by electro-ejaculation and subjected to cryopreservation for subsequent storage in a genome resource bank. Unrelated rams (n=5) were collected 3 days-a-week, allowing at least 2 days of rest between collections. Two ejaculates were obtained from each ram per collection day, with the second collection conducted 10min after the first ejaculation. Semen was processed using the standard Salamon cryopreservation procedure in a Tris-yolk-glycerol extender, frozen in 0.5ml plastic straws using liquid nitrogen (LN(2)) vapor and stored in LN(2). Each ejaculate was evaluated for volume, sperm concentration/ml (x10(9)/ml), number of spermatozoa/ejaculate (x10(9)), sperm progressive motility (%) for pre-cooled semen, cooled semen and semen after thawing. For the five rams, each semen variable for the first ejaculate was compared with that of the second ejaculate collected 10min later. The mean semen volume, sperm concentration and number of spermatozoa per ejaculate obtained from the first ejaculate were significantly greater (P< or =0.01) than those of the second ejaculate (comparisons being 1.62 and 1.06; 3.2 and 1.5; 5.4 and 1.8, respectively). Overall, the mean motility of pre-cooled (22 degrees Celsius), cooled (5 degrees Celsius) and frozen (-196 degrees Celsius) post-thawed spermatozoa was less (P< or =0.01) in the first ejaculate (71.5, 64.8 and 34.1%, respectively) compared with that of the second ejaculate (75, 72.4 and 44.1%, respectively). Conversely, no differences were detected in loss in the percent progressive motility of sperm from cooled sperm to post-thaw sperm from the first and second ejaculates. In summary, our findings suggest sperm collected during the second ejaculate 10min after the first ejaculate of rams survives thawing with a greater rate of progressive motility than that of the first ejaculate. The ability to collect two consecutive ejaculates in a short period by electro-ejaculation could be valuable for gamete resource banking and preserving genetic diversity of the Gulf Coast Native sheep.     

Identification of sperm subpopulations with defined motility characteristics in ejaculates from Florida goats

The aims of this study were to test the presence of discrete sperm subpopulations in Florida goat ejaculates using a computer-assisted sperm analysis (CASA) system and to establish the relationship between the distribution of the subpopulations found and individual buck, total motility, and sperm concentration. Clustering methods and discriminant analysis were applied to identify motile sperm subpopulations within the semen samples. Principal component analysis revealed that three principal components represented more than the 88% of the variance. After the cluster analysis was performed four motile sperm subpopulations were identified. Subpopulation 1 consisted of rapid and linear sperm (39.84%), Subpopulation 2 consisted of slow but linear spermatozoa (33.23%), Subpopulation 3 consisted of rapid, high ALH but non-linear spermatozoa (14.63%), and Subpopulation 4 consisted of slow and non-linear spermatozoa (12.31%). There were significant differences in the distribution of the four subpopulations (P < 0.001) as well as in the percentage of total motility and the overall sperm concentration (P < 0.05) in fresh ejaculates among the four bucks tested. In conclusion, four well-defined motile sperm subpopulations were identified in Florida goat ejaculates. The relationship between the distribution of the sperm subpopulations and individual buck, total motility, and sperm concentration shows that the spermatozoa of each have different motility patterns. Therefore, the study of discrete subpopulations of motile spermatozoa could lead to a substantial increase in information acquired during caprine semen analysis.     

Frequent semen collection and sperm reserves of the male Angora goat (Capra hircus).

Semen was collected from six mature and sexually rested Angora bucks at one-hour intervals five times a day on each of 5 consecutive days in the breeding season. There was a marked decline in semen volume (P less than 0.001), sperm concentration (P less than 0.05) and number of spermatozoa (P less than 0.001) on consecutive days. Successive ejaculates within days differed only in number of spermatozoa (P less than 0.001). The following year at the beginning of the breeding season, the weights of testes and epididymides and the reserves of spermatozoa in these parts were examined after slaughter of the six bucks. The mean number of spermatozoa in the paired testes, capita, corpora and caudae of the epididymides were (22.8 +/- 1.24) x 10(9), (9.4 +/- 1.19) x 10(9), (3.4 +/- 0.22) x 10(9) and (35.0 +/- 2.21) x 10(9), respectively. Epididymal reserves of spermatozoa were correlated with testicular weight (r = 0.50, P = 0.01) and number of spermatozoa in the testes (r = 0.42, P = 0.07), but not with epididymal weight. The daily production of spermatozoa per animal in the breeding season was estimated to be 4.0-6.4 x 10(9).     

Effects of age and environmental factors on semen production and semen quality of Austrian Simmental bulls

More than 90% of the breeding stock of Austrian dual purpose Simmental cows is artificially inseminated. Knowledge of factors affecting sperm production and semen quality is of importance with regard to reproductive efficiency and thus genetic improvement as well as for the productivity and profitability of AI centers. Hence, semen data from two Austrian AI centres collected in the years 2000 and 2001 were evaluated. In total, 3625 and 3654 ejaculates from 147 and 127 AI bulls, respectively, were analysed regarding ejaculate volume, sperm concentration, percentage of viable spermatozoa in the ejaculate, total spermatozoa per ejaculate and motility. Effects accounted for were the bull (random), age of bull, collection interval, number of collection on collection day, bull handler, semen collector, temperature on day of semen collection, in the course of epididymal maturation (average temperature of days 1-11 before collection) and during spermatogenesis (average temperature of days 12-65 before collection). Age of bull significantly affected all traits (P<0.01 to P<0.001) except motility score in center 2. Ejaculate volume and total number of spermatozoa increased with age of bull while sperm concentration was lower in higher age classes (center 1). The collection team was also found to significantly influence semen quality traits. With increasing collection interval ejaculate volume and total number of spermatozoa increased significantly (P<0.05 to P<0.001) while collection intervals between 4-9 days and 1-6 days were superior with regard to sperm concentration and percentage of viable spermatozoa, respectively (P<0.10 to P<0.001). First ejaculates were superior with respect to ejaculate volumes, sperm concentrations and total number of spermatozoa per ejaculate (P<0.001). Temperature, either on day of semen collection or during epididymal maturation or spermatogenesis, had important but inconsistent effects on semen production and sperm quality. Overall, however, ambient temperatures in the range of 5-15 degrees C were found to be optimal for semen production.     

The effect of sperm concentration in the ejaculate on morphological traits of bull spermatozoa

Experiments were performed on 75 ejaculates obtained from 19 bulls representing different cattle breeds used at the Masovian Centre for Animal Breeding and Reproduction in ?owicz. Fresh ejaculates were measured in respect to their volume and sperm count in the ejaculates was determined. The ejaculates were classified based on the criterion of sperm concentration and divided into five groups. Sperm morphometric measurements were taken from each bull and assessment of semen morphology was done on the basis of examination under a microscope using preparations made from fresh ejaculates. For each slide, morphometric measurements were taken of 15 randomly selected spermatozoa characterised by normal morphology and well visible under the microscope. Additionally, in each preparation morphometry of 500 spermatozoa was evaluated, numbers of spermatozoa with normal morphology and morphological abnormalities were recorded and these were categorized into spermatozoa with major and minor defects. An insignificant correlation was observed between the sperm concentration in the ejaculate and morphological traits, dimensions and shapes of bull spermatozoa. The less concentrated ejaculates contained spermatozoa with a slightly larger head circumference and a more elongated head shape in comparison with the spermatozoa in the more concentrated ejaculates. The highest frequency of morphologically malformed spermatozoa, both in the case of primary and secondary alterations, was observed in ejaculates with sperm concentration of no more than 1000 x 10(3)/mm3.     

Sperm selection capacity of the human zona pellucida.

Previous hemizona assay (HZA) results have illustrated a positive and significant correlation between the percentage of morphologically normal spermatozoa in the semen and the number of spermatozoa tightly bound to the zona pellucida. The present study was designed to evaluate the morphologic features using strict criteria of spermatozoa tightly bound to the zona pellucida. Semen samples of 4 normozoospermic and 11 teratozoospermic men were used to compare the percentage of normal spermatozoa in the semen with that found 1) after swim-up separation and 2) bound to the zona under HZA conditions. The mean (+/- SEM) % normal forms for normozoospermic men in semen, after swim-up and zona-bound spermatozoa were 21.5 +/- 1.6, 27.5 +/- 2.9, and 44.8 +/- 3.4, respectively. A significantly higher % of normal forms were found among zona-bound sperm compared to swim-up forms (p = 0.02) and seminal sperm (p = 0.02). The mean % of normal sperm forms present in semen, after swim-up and zona pellucida-binding for teratozoospermic men, were 3.7 +/- 0.9, 5.8 +/- 1.6 and 15.6 +/- 3.1, respectively. Significant differences existed between the % of normal sperm forms found in the swim-up and zona-bound spermatozoa (P = less than 0.01 and P = less than 0.0003, respectively) compared to the original ejaculates. Results indicate that a selective process against abnormal spermatozoa occurs at the site of the zona pellucida.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cellular and biochemical characteristics of semen obtained from pubertal chimpanzees by masturbation

Semen characteristics were studied in 6 wild-born chimpanzees with dental ages ranging approximately from 6 to 12 years. The animals formed 2 groups, early pubertal (EP, N = 3, 6-9 years) and late pubertal (LP, N = 3, 11-12 years). Mean body weight, testicular volume and serum androgen concentration were significantly lower in Group EP (32.2 +/- 1.6 kg, 34.0 +/- 7.7 cm3, 2.1 +/- 0.1 ng/ml) than in Group LP (55.7 +/- 5.7 kg, P less than 0.01; 100.5 +/- 11.9 cm3, P less than 0.01; 3.6 +/- 0.7 ng/ml, P less than 0.05). Ejaculates were obtained by masturbation in all subjects. The mean ejaculate volume was lower in Group EP (0.56 +/- 0.20 ml) than in Group LP (3.77 +/- 0.73 ml, P less than 0.01). In Group EP, 2 animals were azoospermic while the third produced semen with means of 57.1 x 10(6) spermatozoa per ml, 20% motility and 40% vitality. These values were low when compared with the mean values of Group LP (376 x 10(6) spermatozoa per ml, 67% motility and 78% vitality). Mean total sperm count was correlated with testicular volume (r = 0.84) and serum androgen concentration (r = 0.96). The mean concentrations of L-carnitine, fructose, citrate and acid phosphatase for the two groups were not significantly different; but, related to the differences in ejaculate volumes, their total amounts in total ejaculate were lower in Group EP than in Group LP. These results suggest that, in chimpanzees, mechanisms of seminal plasma production and ejaculation are functional early in the reproductive life and that the emission of spermatozoa occurs later.     

Effect of season on some characteristics of stallion semen.

Season had a pronounced effect upon seminal pH and refractometer 'protein', total carbohydrate, dry weight, total N2 and lactic acid in seminal plasma of first and second ejaculates. In addition, total seminal volume, spermatozoa per ml and per ejaculate, non-protein sulphhydryl and glycerylphosphorylcholine of second ejaculates were also influenced. There was a season difference in the concentrations of lactic acid in spermatozoa from first and in total N2 from spermatozoa in second ejaculates. The effects of season on seminal plasma were greater than those on spermatozoa. Spermatozoa in first ejaculates were less affected by season than those in secons ejaculates. This differential effect on first and second ejaculates was generally true of all seminal characteristics.     

The effect of buffer osmolality on the survival of cat (Felis catus ) spermatozoa at 5 degrees C

Cat semen was diluted at 37 degrees C in Tes-Tris buffer (TesT), pH 7.5, at osmolalities ranging from 195 to 390 m0sm/kg, cooled to 5 degrees C over 90 minutes and stored for 24 hours at that temperature. Motility and percentage of spermatozoa staining with a supravital stain were estimated before cooling, after cooling and after storage for 24 hours. The osmolality of undiluted pooled ejaculates from five animals was measured, and also that of different diluents (citrate with phosphate buffer, lactose and TesT-egg yolk) used for cat semen. The osmolality measurements of cat semen suggested an osmolality of less than 320 m0sm/kg at ejaculation, increasing with time after ejaculation. Varying the egg yolk concentrations (2% to 20%) did not affect the osmolality of TesT diluent. Diluent osmolalities of less than 292 m0sm/kg were found to reduce sperm motility significantly (P <0.001 ) although there was no significant increase in the percentage of cells staining with a supravital stain, while those greater than 325 m0sm/kg increased the variation of response among animals. Cooling and storage significantly reduced motility (P <0.01 to P <0.001 ) and increased the number of stained cells (P <0.001 ). There were significant differences between ejaculates (P <0.01 ) and significant interactions between osmolality and cooling/storage (P <0.05 to P <0.001 ). The best overall results were seen with a TesT diluent of 292 to 325 m0sm/kg which supported good motility for at least 24 hours.     

Evaluation of post-thaw Asian elephant (Elephas maximus) spermatozoa using flow cytometry: the effects of extender and cryoprotectant

Although the development of semen cryopreservation in the African elephants (Loxodonta africana) has been accomplished, effective procedures for cryopreservation of Asian elephant (Elephas maximus) spermatozoa have not been established. In the present study, we investigate the freezing methods for conservation of Asian elephant spermatozoa under field conditions and identify the most suitable freezing protocols which provide acceptable post-thaw semen quality. Semen was collected from two Asian elephant bulls (EM1 and EM2, 10 ejaculates from each bull) by manual manipulation and were assessed for volume, pH, sperm cell concentration, and progressive motility. Eight out of 20 ejaculates were of acceptable quality (progressive motility >/= 60%), and were used for cryopreservation studies. Semen were frozen in TEST + glycerol, TEST + DMSO, HEPT + glycerol, or HEPT + DMSO. The post-thaw progressive sperm motilities were assessed, and sperm cells were stained with PI and FITC-PNA for membrane and acrosomal integrity assessment using flow cytometry. Post-thaw progressive motility of spermatozoa (EM1: 42.0 +/- 4.3%; EM2: 26.0 +/- 17.3%) and the percentage of membrane and acrosome intact spermatozoa (EM1: 55.5 +/- 8.1%; EM2: 46.3 +/- 6.4%) cryopreserved in TEST + glycerol were significantly higher than (P < 0.05) those frozen in the other medium investigated choices for cryopreservation of Asian elephant spermatozoa. The data support the use of TEST + glycerol as an acceptable cryopreservation media of Asian elephant semen for the establishment of sperm banks.     

Improvement of boar sperm cryosurvival by using single-layer colloid centrifugation prior freezing

The aim of this experimental study was to evaluate the effectiveness of sperm selection using single-layer centrifugation (SLC) prior to freezing on the sperm cryosurvival of boar ejaculates. Twenty-four sperm rich ejaculate fractions (SREF), collected from 24 boars (one per boar), were divided into two groups according to their initial semen traits: standard (n = 15) and substandard (n = 9). Semen samples from each SREF were split in two aliquots, one remained untreated (control samples) and the other was single-layer centrifuged (500g for 20 min) using 15 mL of Androcoll-P Large (SLC samples). The yield of total, motile (assessed by CASA) and viable (cytometrically evaluated after staining with H-42, propidium iodide (PI) and FITC-PNA) sperm after SLC was higher (P < 0.05) in standard than substandard semen samples. The semen samples were cryopreserved using a standard 0.5-mL straw freezing protocol. Post-thaw sperm motility and viability (assessed at 30 and 150 min post-thawing) were higher (P < 0.05) in SLC than in control samples, regardless of the initial semen traits of the ejaculates. Additionally, thawed spermatozoa from SLC samples were more resistant (P < 0.05) to lipid peroxidation (BIOXYTECH MDA-586 Assay Kit) than those from control samples, regardless of the initial semen traits of the ejaculates. The SLC-treatment also influenced the functionality of thawed spermatozoa undergoing an in vitro capacitation process. The percentage of viable sperm showing high membrane fluidity (assessed with merocyanine 540) was lower (P < 0.05) in the SLC than in the control samples, regardless of the initial semen traits of the ejaculates. Thawed viable spermatozoa of SLC samples generated less (P < 0.05) reactive oxygen species (assessed with CM-H₂DCFDA) than those of control samples in the substandard ejaculates. These findings indicate that the sperm selection before freezing using SLC improves the freezability of boar sperm.