Characteristics and seasonal variations in the semen of Alpine, Saanen and Damascus goat bucks born and raised in Greece

Twenty-three purebred Alpine (n=8), Saanen (n=7) and Damascus (n=8) goat bucks raised at the Institute of Reproduction and Artificial Insemination in Thessaloniki, Greece (40 degrees 37 minutes N, 22 degrees 58 minutes E and altitude 32 m above sea level), were used to study the effect of photoperiod on semen production. Samples were collected with an artificial vagina and examined immediately after collection. In spite of the variation in nearly all semen characteristics studied among the 3 breeds of bucks, there was significant seasonal variation in both semen quantity (volume, concentration and total number of spermatozoa per ejaculate) and quality (percentage of motile spermatozoa, percentage of abnormal spermatozoa and rate of progressive motility). The best semen was produced during the breeding season (late summer and autumn). However, the magnitude of these seasonal effects was not sufficient to prevent bucks from being used for breeding throughout the year. Nevertheless, individual differences in the semen quantity and quality among bucks within a breed make individual evaluation of semen necessary to select the most fertile males for breeding.     

Prefreezing and post-thaw semen characteristics of five ram breeds collected by electroejaculation

Rams representing five breeds were electroejaculated twice weekly, during a three-week collection period. Ejaculates were evaluated for volume and concentration before freezing and for rate of motility and percentages of motile and abnormal cells both before and after freezing. Interactions between breed and collection period were evident (P<0.05) for semen volume and post-thaw values for rate of motility and percentage motile cells. Breeds differed (P<0.05) in these traits during some periods. In contrast, pre-freezing observations of rate of motility, percentage motile and abnormal cells and post-thaw percentage abnormal cells did not differ (P>0.15) among breeds. Sperm concentration per ejaculate tended to vary (P=0.11) among breeds. Semen characteristics frequently varied across collection periods. Rams within a breed differed (P<0.01) in all semen traits except post-thaw rate of motility and percentage motile cells. Semen was negatively affected by the freezing and thawing procedure. Ram within a breed and ejaculate within ram should be considered when selecting electroejaculated semen for freezing and subsequent use in artificial insemination.     

Fertility of fresh and frozen-thawed goat semen during the nonbreeding season

A total of 4109 does of a local Greek breed (Capra prisca) were synchronized with intravaginal MPA-sponges and PMSG, and 24 bucks of Alpine (n = 8), Saanen (n = 8) and Damascus (n = 8) breeds were used for studying the fertility of nonfrozen and frozen-thawed semen during the nonbreeding season (June to August). Artificial insemination (AI) was performed once (50 to 55 h after sponge withdrawal) or twice (36 and 60 h after sponge withdrawals with fresh semen (collected during the nonbreeding season, stored at 16 degrees C and inseminated within 6 h) or frozen semen (prepared from the same bucks during the preceding breeding season). The induction of estrus was successful, varying between 91.0 and 95.0%. The form of semen (fresh or frozen-thawed used for inseminating the synchronized does affected their fertility: the overall kidding rate with fresh semen (65.5%) was higher (P < 0.05) than that with frozen-thawed semen (53.4%). The fertility level was also affected by the number of inseminations performed: the overall kidding rate was significantly higher (P < 0.001) in the does inseminated twice with fresh or frozen-thawed semen (70.4 and 59. 1%, respectively) than in those inseminated only once (48.9 and 44.9%, respectively). Finally, the breed of the buck used for preparing the fresh or the frozen-thawed semen affected the fertility level of the does. The kidding rate was higher in does inseminated with fresh semen prepared from bucks of the Damascus breed than from bucks of Saanen or Alpine breed. However, when frozen-thawed semen was used the kidding rate was lower in does inseminated with semen prepared from bucks of the Damascus breed than from bucks of the Alpine or Saanen breed. It is concluded that the fresh semen of Alpine, Saanen and Damascus breed bucks, born and raised under the climate conditions prevailing in Greece (34 degrees to 41 degrees N), can be used successfully during the nonbreeding season (June to August) for inseminating does.     

The expression of the aryl hydrocarbon receptor in reproductive and neuroendocrine tissues during the estrous cycle in the pig

The sprouted wheat (SW) contains the 6-methoxy-2-benzoxazolinone (6-MBOA), a phenol compound that stimulates reproduction in certain small wild herbivorous mammals. The objective of the present study was to evaluate the effect of short-term supplemental dietary SW on libido, semen and sperm characteristics of rabbit bucks. Five-month old New Zealand White pubertal rabbits (n=18) were randomly allocated to one of two treatments: supplementation or not (control) supplemented with SW. The experimental design was completely random with nine replications, experimental unit was one buck. Semen collection for each male was conducted once a week with two ejaculations during 20 weeks. The SW was given during four consecutive days prior to each semen collection. Analysis of variance was under a mixed model: treatment, ejaculate number and season were fixed and rabbit random effects. There was no effect of treatment (P>0.05) on reaction time, gel presence, volume, pH, sperm motility, sperm number per ml and sperm number per ejaculate. The percentage of normal alive spermatozoa was 13.5% greater in SW-supplemented bucks than in the control and the percentage of abnormal alive spermatozoa was 44.1% greater in the control than in the SW-supplemented bucks. The morphology of dead spermatozoa, integrity of acrosome, number of normal alive motile sperm and semen doses per ejaculate were not influenced (P>0.05) by SW supplementation. The proportion of presence of gel and semen volume in the first ejaculate was greater than the second ejaculate (+140% and +56.4%). However, the semen quality in the latter was greater (P=0.0001) than the former in terms of an increase in motility (+29.7%). Reproductive traits were more desirable (P<0.05) in winter than autumn. Dietary wilted SW as a source of biological 6-MBOA enhanced sperm characteristics in terms of a greater percentage of normal alive and lesser percentage of abnormal alive spermatozoa but did not affect the number of normal motile live sperm and suitable semen doses in rabbit bucks in autumn and winter.     

Development of macroscopic and microscopic characteristics of ejaculates from Chios, Serres and Karaguniki breed lambs

The developmental characteristics in the volume of the ejaculate, motility (percentage of motile spermatozoa) and grade of motility (vitality), density, total number of spermatozoa per ejaculate and percentage of dead (stained) and of morphologically abnormal spermatozoa were studied in 14-to 46-week-old lambs of the Chios (n=10), Serres (=10) and Karaguniki (n=10) breeds, born in October 1984. The first appearance of spermatozoa in the ejaculate of the Chios, Serres and Karaguniki lambs occurred at 20.1+/-0.31 (x +/-SEM), 20.4+/-0.37 and 20.6+/-0.54 weeks of age, respectively, when the lambs had attained a body weight of 36.4+/-, 36.5+/-0.70 and 34.9+/-0.99 Kg, respectively. The volume of the ejaculate, the motility and the grade of motility of spermatozoa increased at a rapid rate up to the age of 32 weeks, when the relevant values were the same as those found in the adult animal. Density of the semen and the total number of spermatozoa per ejaculate increased at a slower rate up to the age of 46 weeks, while the percentages of dead (stained) and of morphologically abnormal spermatozoa decreased significantly between 20 and 32 weeks of age. It is concluded that the quality of the semen at the time when the first spermatozoa appear in the ejaculate is not satisfactory, but it improves in the course of the ensuing 2 to 3 months. The optimal age at which the lambs may be used for artificial insemination are 32, 36 and 34 weeks for the Chios, Serres and Karaguniki breeds, respectively.     

The relationship between rabbit semen characteristics and reproductive performance after artificial insemination

The relationships between several rabbit buck semen traits, concerning either the ejaculate or the dose inseminated (volume, mass motility, pH, percentage of motile sperm (PMS), concentration, number of total and motile sperm per ejaculate and per insemination dose) and the reproductive performance of does was investigated in 839 inseminations involving 54 bucks and 111 does. Four genetic types were involved: INRA1601 strain (A), INRA2066 strain (B) and the two reciprocal crossbreds (AB and BA). The mating design was A x A, B x B, (AB or BA) x (AB or BA). Semen was diluted (1:9) and a constant volume of 0.5 ml was inseminated 2-4h after collection. Therefore, the total number of spermatozoa per dose was variable and proportional to the initial concentration. Mass motility significantly influenced the kindling rate. Taken separately, volume, PMS and concentration did not influence the kindling rate but their product, the number of motile sperm per ejaculate, did. Litter size (total born) was significantly influenced by concentration and all variables depending on it, particularly the number of total and motile sperm per dose. However, reproductive performances were predominantly influenced by the physiological status of the does at insemination (lactation stage and receptivity).     

The value of the percentage of motile sperm in predicting a significant portion of the fertility variation of frozen-thawed buck semen

Prediction of the future fertility of a given ejaculate with a simple laboratory test is still considered a real issue in domestic mammal breeding. This study showed that a subjective assessment of the percentage of motile spermatozoa, measured 120 min after thawing (mob120), can predict a significant part (∼50%) of the variation of the future fertility of buck ejaculates. The predictive model was calculated using a calibration data set composed of 40 ejaculates from four Alpine and six Saanen bucks. A fertility trial using split ejaculates was conducted in order to estimate ejaculate fertility. Taken into account were the herd within breed factor and the year, month, and inseminator factors. On average, one ejaculate was used to inseminate two females per herd in 10 different herds. This calibration set allowed us to choose the mob120 variable among a set of laboratory tests: mitochondrial activity, acrosomal status, membrane integrity, osmotic resistance test assessed by flow cytometry, velocity and motion characteristics assessed by computer-assisted sperm analysis, visually assessed percentage of motile, and motility score measured 5 and 120 min after thawing. For the calibration step, the best model used the logarithm of mob120 and gave a correlation coefficient of 0.71 between the field fertility and the predicted fertility and a standard error of 0.17. We tested this model on 3 different validation data sets adding up to 95 ejaculates that were all different from those of the calibration data set. The correlation coefficients between field fertility and predicted fertility were always significant and the bias corrected standard error ranged from 0.15 to 0.18 on these validation data sets. A Monte Carlo simulation showed that about 20% of the fertility variation remained to be explained.     

Genetic and environmental effects on semen traits in Lacaune and Manech tête rousse AI rams (Open Access publication)

Data from 51 107 and 11 839 ejaculates collected on rams of the "Lacaune" and "Manech tête rousse" breeds, respectively, were analysed to determine environmental and genetic factors affecting semen production traits (ejaculate volume, semen concentration, number of spermatozoa and motility) in young (≤1 year) and adult (≥2 years) rams. Fixed effects and variance components were estimated using multiple trait animal models within each breed. For all traits, the main environmental effects identified were year, season, number of ejaculations, daily variation, interval from previous to current collection and age. Heritability estimates were moderate for volume, concentration and number of spermatozoa (0.12 to 0.33) and lower for motility (0.02 to 0.14). Genetic correlations between ages differed from 1 for all traits (0.14 to 0.90), indicating that semen characteristics corresponded to different traits in young and adult rams. Genetic and phenotypic correlations among traits within age category were globally similar for the different breeds and categories of animals.     

Semen quality in dogs and the influence of a short-interval second ejaculation

Semen quality was examined in each of 65 known fertile dogs. Values were found to be similar to those previously published, although an apparent breed influence was demonstrated, with German shepherd dogs producing ejaculates of larger volume and greater total spermatozoal output than other breeds. A second ejaculate was collected from each dog with a mean interval of 63 min. The second samples had significantly lower values for the volume of the second fraction, the spermatozoal concentration and the total spermatozoal output. There were no differences for the percentage motility or the percentage of morphologically normal live spermatozoa. While there was no increase in semen quality of the second ejaculate, the technique may be useful since it results in the collection of approximately 70% more spermatozoa than a single ejaculate. These spermatozoa also had normal motility and morphology and could, therefore, be used for insemination or cryopreservation.     

The effect of zwitterion buffers on the freezability of Boer goat semen

Twenty semen samples with mass activity greater than +3 were collected from six healthy, mature Boer goat bucks. Each ejaculate was divided into four equal parts and extended at 37 degrees C in Tris, Test, Tes and Bes buffers containing egg yolk and glycerol. Semen was placed into medium size French strawsand after 2 hours of equilibration at 5 degrees C, frozen in the vapour phase and stored in liquid nitrogen for 7 days at -196 degrees C. Progressive motility, the number of live spermatozoa and glutamic oxaloacetic transaminase (GOT) release were studied after the initial extension, after equilibration and after 15 minutes and 7 days of freezing of semen. Semen samples when extended with Tris yolk glycerol showed significantly (P<0.01) higher progressive motility and live spermatozoa than when extended with the other zwitterion buffer-based extenders. The change of extenders did not influence the release of GOT at various stages of freezing of semen (P>0.05).     

The influence of age and breed on stallion semen

This study reports on the variation in semen quality and in spermatozoal and behavioral characteristics of 168 stallions representing 9 breeds and ranging in age from 2 to 26 yr. Semen samples were collected into an artificial vagina and the number of mounts and urethral pulsations per semen sample were recorded. Semen characteristics were examined for total volume, gel-free volume, gel volume, color score, mass activity, nonmotile spermatozoa, dead spermatozoa, semen density, spermatozoa concentration, total number of spermatozoa and semen pH. Morphological characteristics of the spermatozoa included abnormal heads, abnormal mid-pieces, abaxial mid-pieces, protoplasmic droplets and abnormal tails. Sources of variation were evaluated and the overall means calculated by least-squares analyses of variance for nonorthogonal data. The significance of breed effects and between stallion variability were estimated using mixed-model procedures. All semen characteristics with the exception of color and urethral pulsations had significant variation due to age. Semen quality (gel-free volume, sperm concentration, total sperm numbers and sperm abnormalities) was poorest in stallions under 3 yr of age and over 11 yr. Significant breed variation was apparent in most characteristics except for pH, semen color, abnormal midpieces and urethral pulsations. It is recommended that both the age and breed of stallion be taken into consideration when evaluating stallion semen.     

Effect of spermatozoal concentration and number on fertility of frozen equine semen

Information on the number of motile spermatozoa needed to maximize pregnancy rates for frozen-thawed stallion semen is limited. Furthermore, concentration of spermatozoa per 0.5-mL straw has been shown to affect post-thaw motility (7). The objectives of this study were 1) to compare the effect of increasing the concentration of spermatozoa in 0.5-mL straws from 400 to 1,600 x 10(6) spermatozoa/mL on pregnancy rate of mares, and 2) to determine whether increasing the insemination dose from approximately 320 to 800 million progressively motile spermatozoa after thawing would increase pregnancy rates. Several ejaculates from each of 5 stallions were frozen in a skim milk-egg yolk based freezing medium at 2 spermatozoal concentrations in 0.5-mL polyvinyl-chloride straws. Half of each ejaculate was frozen at 400 x 10(6) cells/mL and half at 1,600 x 10(6) cells/mL. Insemination doses were based on post-thaw spermatozoal motility and contained approximately 320 x 10(6) (320 to 400) motile spermatozoa or approximately 800 x 10(6) (800 to 900) motile spermatozoa. Sixty-three mares were assigned to 1 of 4 spermatozoal treatments (1--low spermatozoal number, low concentration; 2--low spermatozoal number, high concentration; 3--high spermatozoal number, low concentration; 4--high spermatozoal number, high concentration) and were inseminated daily. Post-thaw spermatozoal motility was similar for cells frozen at both spermatozoal concentrations (P > 0.1). One-cycle pregnancy rates were 15, 40, 28 and 33%, respectively, for Treatments 1, 2, 3 and 4. Packaging spermatozoa at the high concentration tended to increase pregnancy rates vs packaging at the low concentration (37 vs 22%; P = 0.095). Furthermore, when the lower spermatozoal number was used, there tended (P < 0.1) to be a higher pregnancy rate if spermatozoa were packaged at the higher concentration. There was no increase in pregnancy rates when higher numbers of motile spermatozoa were inseminated (27 vs 31%; P > 0.1). Based on these results, a single 0.5-mL straw dose containing 800 x 10(6) spermatozoa should be used and each insemination dose should contain approximately 320 x 10(6) motile spermatozoa. Fertility trials utilizing other freezing extenders are necessary before recommending a single 0.5-mL insemination dose for all freezing extenders.     

Effect of initial freezing temperature on the semen characteristics of frozen-thawed ram spermatozoa in a semi-arid tropical environment

Ram spermatozoa are sensitive to extreme changes in temperature during the freeze-thaw process. The degree of damage depends on a combined effect of various factors including initial freezing temperature. The present study was conducted to observe the effect of initial freezing temperature on post-thawing motility of ram spermatozoa of native and crossbred rams maintained in a semi-arid tropical environment. Good quality semen obtained from native Malpura and crossbred Bharat Merino rams were pooled within breed and diluted at a rate of 1000 million spermatozoa per milliliter in TEST—yolk–glycerol extender. Diluted semen samples were loaded in 0.25 ml straws and cooled to −25, −75 or −125 °C freezing temperature at the rate of −25 °C/min under controlled conditions before plunging into liquid nitrogen for storage. The thawing of straws was performed at 50 °C in a water bath for 10 s and motility characteristics of the frozen-thawed spermatozoa were assessed by a computer-assisted spermatozoa analysis technique. Initial freezing temperature significantly affected the post-thawing motility of sperm in both the breeds. The post-thawing % motility and rapid motile spermatozoa were significantly higher at initial freezing temperature of −125 °C and lower at −25 or −75 °C. The percentage medium motile sperm were similar at all three initial freezing temperatures. The percentage of slow motile and linearity of sperm varied (P<0.01) between the different freezing temperatures. The curvilinear velocity, average path velocity and straight line velocity of spermatozoa were higher (P<0.01) at −125 °C than −25 or −75 °C. Although the lateral head displacement of spermatozoa did not vary significantly between the different initial freezing temperatures, the stroke frequency was significantly lower at −25 °C than −75 or −125 °C. Except for % linearity, the average path velocity and straight line velocity, other spermatozoa characteristics were not significantly different between breeds. The interaction between freezing temperature and breed was significant only for the % motility and linearity of the spermatozoa. The study indicates that initial freezing temperature has a significant effect on spermatozoa motility and velocity following post-thawing. The best motile spermatozoa following thawing were achieved at −125 °C freezing temperature.     

Effects of season and breed on sperm acrosin activity and semen quality of boars

Acrosin activity and semen quality (sperm concentration, ejaculate volume and number of spermatozoa) were assessed from March 1997 to March 1998 in semen of Large White, Pietrain and Duroc x Pietrain boars. Semen quality varied with season, including high production of spermatozoa in autumn and winter and low production in summer. Semen quality also differed across breeds. Acrosin activity of boar spermatozoa was not affected by breed (range 3.16-3.32 mU/10(6) spermatozoa), but exhibited distinct seasonal changes. Monthly changes in acrosin activity were parallel to changes in number of sperm in the ejaculate from November to March. On the other hand, dramatic changes in acrosin activity between July and October (range 1.85-4.59 mU/10(6) spermatozoa) were not paralleled by similar changes in number of ejaculated sperm. These fluctuations in acrosin activity may reflect either changes in sperm acrosin production or disturbances to sperm membranes, probably related to effects of high summer temperatures during spermatogenesis. Results confirmed seasonal and breed-related differences in boar semen quality characteristics.     

Effect of glycerolization procedure and removal of seminal plasma on post-thaw survival and got-release from Boer goat spermatozoa

Forty ejaculates (20 for each of 2 experiments) were collected from 4 Boer goat bucks at weekly intervals to study the effect of glycerolization procedure and removal of seminal plasma on progressive motility, percent live spermatozoa and release of glutamic oxaloacetic transaminase (GOT) before and after the freezing of semen. Stepwise glycerolization at 37 degrees C gave higher progressive motility and percentage of live spermatozoa both before freezing and after thawing than onestep glyceroliza-tion at 37 degrees C or stepwise extension with glycerol being added after cooling to 5 degrees C. The GOT-release was reduced before freezing and after thawing of semen with stepwise glycerolization (P < 0.05). Progressive motility and the percentage of live spermatozoa were higher (P < 0.05) after the freezing of whole semen than in washed spermatozoa. The concentration of GOT in the extra-cellular fluid was lower in washed spermatozoa prior to freezing (P < 0,05); but after thawing, the washed spermatozoa released more GOT than spermatozoa in whole semen. Removal of seminal plasma prior to freezing spermatozoa in an extender containing egg yolk had an unfavorable effect on their post-thaw motility and integrity.     

Seminal carnitine and acetylcarnitine content and carnitine acetyltransferase activity in young Maremmano stallions

The reproductive characteristics and seminal carnitine and acetylcarnitine content as well as carnitine acetyltransferase activity of young Maremmano stallions (n=25) are reported. The stallions were subjected to semen collection in November and January; in each trial two ejaculates were collected 1h apart. The total motile morphologically normal spermatozoa (TMMNS) and the progressively motile spermatozoa at collection and during storage at +4 degrees C were evaluated. Seminal L-carnitine (LC), acetylcarnitine (AC), pyruvate and lactate were measured using spectrophotometric methods, whereas carnitine acetyltransferase activity was measured by radioenzymatic methods. Since there were no major significant differences in seminal and biochemical characteristics between the November and January trials, data were also pooled for the first and second ejaculates. Significant differences (P<0.001) were observed between the first and second ejaculates for sperm count (0.249+/-0.025 versus 0.133+/-0.014x10(9)/ml), total number spermatozoa by ejaculate (12.81+/-1.23 versus 6.36+/-0.77x10(9)), progressively motile spermatozoa (48.6+/-3.0 versus 52.6+/-3.0%) and TMMNS (3.35+/-0.50 versus 2.02+/-0.37x10(9)). In the raw semen the LC and AC were significantly higher in the first ejaculate than in the second (P<0.001), whereas, pyruvate and pyruvate/lactate ratio were higher in the second ejaculate (P<0.05). Seminal plasma AC and LC concentrations resulted higher in the first ejaculate (P<0.001). The pyruvate/lactate ratio was higher in the second ejaculate (P<0.05). Both raw semen and seminal plasma LC and AC concentrations were positively correlated with spermatozoa concentration (P<0.01); in raw semen AC was also correlated to TMMNS (P<0.01). Lactate levels of raw semen was correlated to progressively motile spermatozoa after storage (P<0.01). In the second ejaculate, significant correlations were also observed among AC/LC ratio in raw semen and progressively motile spermatozoa after 48 and 72h of refrigeration. Furthermore, AC levels were correlated to lactate concentration. The positive correlation between LC, AC and spermatozoa concentration, and between AC and TMMNS indicated carnitine as potential semen quality marker. Moreover, the correlation between AC/LC ratio and progressive spermatozoa motility after refrigeration, suggests that carnitine may contribute towards improving the maintenance of spermatozoa viability during in vitro storage.     

Effects of cadmium chloride administration on the macroscopic and microscopic characteristics of ejaculates from Chios ram-lambs

The effects of cadmium chloride on the volume of the ejaculate, semen density, total number of spermatozoa per ejaculate, viability, grade of motility, and morphological abnormalities were studied in 3-month-old ram-lambs of the Chios breed. Two groups of seven animals each were used. For a period of 7 months, one group was treated with a daily oral dose (3 mg/kg b.w.) of cadmium chloride and the other group received the corresponding volume of doubly distilled water. Blood samples were collected for cadmium determinations, whereas semen was collected weekly. In the cadmium-treated animals, cadmium concentration in the whole blood was increased and the testes weight was lower. The volume of the ejaculate, the semen density and the total number of spermatozoa were significantly reduced by the administration of cadmium chloride. No differences were observed in the viability, the grade motility of spermatozoa, or the percentage of dead and morphologically abnormal spermatozoa between the control and the cadmium-treated animals. Histopathological examination in the cadmium-treated animals revealed the presence of lesions in the Sertoli cells, the seminiferous tubules, the primary and the secondary spermatocytes and the spermatides, whereas in the Leydig cells no significant lesions were evident.     

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.     

Effect of the collection method on semen characteristics of Zebu and European type cattle in the tropics

The effect of the collection method on the characteristics of fresh semen and the recovery of spermatozoa after thawing was studied in 30 Zebu bulls (Bos indicus ) and in 30 Brown Swiss (Bos taurus ) bulls. Semen was collected by using an artificial vagina and by electroejaculation; the ejaculates were individually evaluated. Semen was diluted for freezing in skimmed milk and stored in 0.5-ml French straws, at a concentration of 30 x 10(6) spermatozoa. Data were evaluated by analysis of variance using a factorial model which included collection method, breed effect, and interaction between method and breed, with each bull as a block. Higher volume and pH of the semen was obtained following electroejaculation. Conversely, higher concentration prior to freezing and better progressive motility after thawing was observed in semen collected with an artificial vagina. No differences in motility were obtained in fresh semen between methods. Better post-thaw recovery occurred when the semen was collected by an artificial vagina, independently of the breed type.     

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.