Assessment of Sperm Morphology in Zebu Bulls, under Field Conditions in the Tropics

Sperm morphology was studied in 302 extensively managed Zebu bulls (aged 1.5–9 years), classified as sound (n=166) or unsound (n=136) for breeding, under field conditions in the dry tropics of Costa Rica. Single semen samples were collected by electro‐ejaculation and fixed in formol‐saline solution immediately after collection. Sperm morphology was determined in the field on wet smears using a microscope equipped with phase‐contrast optics, and further determined in the laboratory on air‐dried smears stained with carbol‐fuchsin. The frequencies of sperm abnormalities (such as abnormal acrosome, head, neck, mid‐piece, tail, and presence of cytoplasmic droplets) were recorded as a percentage of the total number of counted spermatozoa (400 cells). Zebu bulls considered unsound for breeding showed a higher mean prevalence (p < 0.05) of knobbed acrosomes (4.0 versus 0.9%), head defects [specifically, nuclear invaginations and heads with abnormal shapes and sizes (27.6 versus 4.0%)], abnormal tails (11.2 versus 4.7%), and proximal droplets (8.4 versus 1.6%), compared with bulls considered sound for breeding. In these latter bulls, the abnormality most commonly seen was the presence of single bent tails with an entrapped cytoplasmic droplet (3.0 ± 3.7%). Young Zebu bulls (i.e. bulls under 2 years of age) showed a higher percentage of missing acrosomes, and proximal cytoplasmic droplets, than older sires (12.1 versus 2.4%, and 23.9 versus 3.6%, respectively; p < 0.05), interpreted as an indication of low ejaculation frequency and sexual immaturity, respectively. Bulls with a long scrotum and soft testicular consistency (TC) at palpation showed higher percentages of abnormal sperm heads in the ejaculate than bulls with a normal scrotal length (SL) and a normal TC (32.7 versus 12.8% and 30.7 versus 10.3%, respectively; p < 0.05). In addition, Zebu bulls with a scrotal circumference (SC) ≤ 30 cm showed a higher prevalence of proximal cytoplasmic droplets than bulls whose SC was > 30 cm (9.8 versus 2.6%, p < 0.05). A higher mean percentage of abnormally sized and shaped heads, especially undeveloped and narrow at the base, was more frequently found in stained smears than in unstained samples (26.0 versus 9.9%, p < 0.05), which clearly underlines the importance of using both stained and wet smears when assessing sperm head morphology. However, for a quick assessment of sperm morphology under field, tropical conditions, phase‐contrast microscopy provides useful information for the spermiogramme evaluation.     

Use of a Giemsa stain to detect changes in acrosomes of frozen ram spermatozoa.

Acrosomal structures of ram spermatozoa were prominently stained when air dried smears of diluted semen were fixed for 15 minutes in buffered formal saline and stained for 90 minutes in a 6 per cent (v/v) buffered solution of Giemsa stain. Progressive disruption of the acrosomes was demonstrated during chilling and deep-freezing of the spermatozoa, and the degree of damage was systematically scored. A rapid and repeatable estimate of the state of the acrosomes in a sample could be made from the mean score of 20 spermatozoa examined per slide.     

Morphological features of spermatozoa of swamp buffalo AI bulls in Thailand

The appearance and incidence of sperm abnormalities was studied in 115 ejaculates, collected periodically over 1 year covering all seasons from five mature, healthy swamp buffalo (Bubalus bubalis) bulls reared under tropical conditions and serving as the current source of semen for artificial insemination (AI) in Thailand. Light microscopy of stained smears was used to investigate sperm head shape morphology, while unstained wet smears were used to examine other sperm abnormalities. The most commonly found morphological aberrations were pear-shaped spermatozoa, knobbed acrosomes, proximal cytoplasmic droplets, simple bent tails and coiled tails under the head, whose ultrastructure (scanning electron microscopy) corresponded to what has been found in other species of bovidae, including varieties of buffalo. The mean prevalence (as least squares mean +/- SEM) of sperm abnormalities was low (below 15%), corresponding to healthy spermiograms. The younger bulls (<10 years old, n = 3) had less abnormalities than the older ones (10.1 +/- 0.6% versus 14.1 +/- 0.8%, P < 0.001, n = 2), including abnormalities of sperm head shape (1.1 +/- 0.3% versus 3.6 +/- 0.3, P < 0.001), acrosome defects with knobbed acrosomes (1.1 +/- 0.2% versus 1.2 +/- 0.3%, P < 0.001), spermatozoa with proximal cytoplasmic droplets (2.7 +/- 0.1% versus 1.4 +/- 0.2%, P < 0.001), defective mid-pieces (0.2 +/- 0.1% versus 0.3 +/- 0.1%) and abnormal sperm tails (3.1 +/- 0.3% versus 5.7 +/- 0.4%, P < 0.001). The within-bull effect of the year solely affected the incidence of pear-shaped spermatozoa while the incidences of abnormal contour, variable size of sperm head shapes, abnormal mid-piece and simple bent tail among bulls were affected by ejaculate (week of collection). Interaction between age and ejaculate affected only the prevalence of spermatozoa with proximal cytoplasmic droplets. In conclusion, the types of defects encountered were similar to those found in other bovidae, with a very low prevalence over the year the AI sires were followed through.     

The knobbed acrosome defect in beef bulls

The knobbed acrosome defect was found at levels of 25 to 100 percent of spermatozoa from 16 of 2054 beef bulls. The incidence of this defect appeared to be particularly high in the Charolais breed. Pedigree analysis of some of the affected Charolais bulls indicated there may be a genetic predisposition for this sperm defect. In eosin-nigrosin stained semen smears the most common form of the abnormality was a flattened or indented apex of the sperm head. A refractile bead at the apex of the sperm head was seen less commonly. Electron microscopy of the spermatozoa from one bull showed that the abnormality was similar to the knobbed sperm defect previously described in Friesian bulls. A breeding trial confirmed that bulls producing spermatozoa with a high incidence of knobbed acrosomes are infertile.     

The Proportion of Beef Bulls in Sweden with Mature Spermiograms at 11–13 months of Age

Semen samples collected postmortem from 142 yearling beef bulls (11-13 months old) of three different breeds (Charolais, Hereford and Simmental) were examined to evaluate the proportion of bulls with mature spermiograms. Before slaughter, testes and epididymides were clinically examined and scrotal circumferences were measured. Aliquots of the cauda epididymal contents taken postmortem were used for sperm morphology examination. Sperm head morphology was studied in dry smears stained with carbol-fuchsine. For each preparation, 500 spermatozoa were counted in each smear under light microscope (x 1000). The presence of proximal cytoplasmic droplets, abnormal acrosomes, detached heads and abnormalities of the midpiece and tail were recorded in wet preparations of formol-saline-fixed spermatozoa. For each preparation, 200 spermatozoa were counted in each preparation under a phase-contrast microscope (x 1000). The abnormalities were classified according to a classification system developed by Bane (1961). Morphological abnormalities were recorded as a percentage of the total number of counted spermatozoa. Criteria for a spermiogram to be considered mature included <15% abnormal heads and <15% proximal droplets. According to this definition approximately 48% (68 of 142) of the examined bulls were considered mature. The bulls in this study represent approximately one-fifth of the total amount of performance-tested beef bulls in Sweden during 5 years. Our results indicate that only less than half of the Swedish yearling beef bulls at the testing station appear to have a mature spermiogram at the time they are offered for breeding purposes.     

Influence of wet fixation, staining techniques, and storage time on bull sperm morphology

The influence on sperm morphology of different methods for preparation of semen and of storage in a fixative solution was examined in 27 beef bulls subjected to a regular breeding health examination. Sperm head morphology under light microscopy did not differ between smears of fresh semen stained with carbol-fuchsin-eosin (Williams staining) or Nigrosin-Eosin. Nor was there any difference between samples stained immediately after collection and those stained after 1 month of storage at + 4 degrees C in buffered formal-saline solution. Formol-saline fixed spermatozoa examined in wet preparations under phase contrast microscopy had a higher prevalence of acrosome defects and cytoplasmic droplets than stained smears of fresh semen under light microscopy. One month of storage in formol-saline did not affect the prevalence of acrosome defects or cytoplasmic droplets. There was no influence of fixation method (wet or dry), staining, examination technique, or storage time on midpiece or sperm tail morphology. The affinity of spermatozoa to eosin at staining with Nigrosin-Eosin ("live and dead count") did not differ between fresh semen and spermatozoa that had been stored in formol-saline for 1 month. It is concluded that bull semen can be stored for at least 1 month at + 4 degrees C in buffered formal-saline without major changes in sperm morphology. Furthermore, examination of wet preparations of fixed spermatozoa under phase contrast microscope is likely to yield the most accurate results for morphological characteristics like acrosome morphology and cytoplasmic droplets.     

Effect of phenylephrine, ergonovine, oxytocin and norepinephrine as an extender ingredient on viability of bovine spermatozoa

We evaluated effects of three concentrations of phenylephrine, ergonovine, oxytocin and norepinephrine (myometrial stimulants) on viability of spermatozoa when they were included in a seminal extender. Using a split ejaculate technique, ejaculates from each of 10 bulls were extended in egg-yolk citrate to a final concentration of 35 x 10(6) sperm/ml, including 20 mg/ml, 2 mg/ml and .2 mg/ml, of phenylephrine or ergonovine, 20 IU/ml, 2 IU/ml and .2 IU/ml oxytocin or 200 micrograms/ml, 20 micrograms/ml and 2 micrograms/ml norepinephrine prior to freezing. Extended semen without a myometrial stimulant served as the control. Percentage of intact acrosomes was determined prior to freezing for all treatments. Motility and percentage of intact acrosomes were determined immediately after thawing (0 h) and again after 4 h incubation at 37 degrees C. Percentage of intact acrosomes was reduced (P less than .05) prior to freezing by phenylephrine (20 mg/ml) and ergonovine (20 mg/ml) (phenylephrine = 56%; ergonovine = 63%; control = 74%). The same doses of phenylephrine and ergonovine reduced (P less than .05) post-thaw motility and percentage of intact acrosomes at both 0 and 4 h compared with controls. Sperm exposed even to the intermediate concentration (2 mg/ml) of ergonovine had lower (P less than .05) motility 4 h post-thaw. No other compound or concentration of compound or concentration of compound affected percentage of intact acrosome or motility. There were no two or three-way bull x compound and concentration interactions (P greater than .2).(ABSTRACT TRUNCATED AT 250 WORDS)     

Migration of protoplasmic droplets and phagocytosis of damaged sperm during their passage through the efferent ducts in boars and bulls

Seventeen gonad pairs of boars and ten gonad pairs of bulls were examined to evaluate the migration of protoplasmic droplets and the phagocytosis of defective spermatozoa. The material for a microscopic investigation of secretions was collected from two sites in the testis and from seven sites in the epididymis. The greatest motion of protoplasmic droplets was recorded in the caput epididymidis, although the migration of droplets from the proximal section of the connective part of the flagellum towards the distal parts could also be observed as far as in the cauda epididymidis in both animals. A proximally located droplet still occurred in the cauda epididymidis in 4.5% of the spermatozoa of boars and in 1.9% of those of bulls. Absent mitochondrial spirals or swollen connective parts were observed in the imprints of testicular tissue in almost 50% of the spermatozoa whereas in the secretion of efferent ducts they were observed only in 0.3% of bull spermatozoa and about 3% of boar spermatozoa. No such defects were recorded in the epididymis head and tail in either of the two species. The marked reduction in the number of defective spermatozoa without mitochondrial spirals in the secretion of efferent ducts and after passage through the caput epididymidis testifies to the phagocytic ability of the epithelium of this part of efferent ducts.     

Effect of unilateral orchiectomy on semen quality in bulls

Unilateral orchiectomy was performed on 9 mature mixed-breed bulls with satisfactory semen quality to study the effect of the procedure on quality of semen from the contralateral testicle. Semen was collected by electroejaculation before surgery and on alternate days for 2 weeks, then once weekly for 8 weeks. Each sampling day, progressive motility and morphologic features of spermatozoa were determined, and scrotal thermograms were taken. The percentage of normal spermatozoa decreased significantly (P less than 0.05) only on postoperative day 6. Progressive motility scores varied but at the end of the study there was no significant difference from preoperative values. Scrotal thermography revealed inflammation in the contralateral side of the scrotum, beginning 3 days after surgery, but the thermograms were normal in most bulls by 3 weeks after surgery, and all thermograms were normal by 4 weeks.     

Reproductive criteria of beef bulls during and after exposure to increased ambient temperature

Sixteen yearling Angus bulls were randomly assigned to one of two temperature-controlled chambers to determine the effects of elevated ambient temperature on body functions and semen characteristics. After 8 wk adjustment at 23 C, eight heat-stressed bulls were exposed to 35 +/- 1 C for 8 h and 31 +/- 1 C for 16 h during each 24-h period, and eight control bulls were maintained at 23 +/- 1 C for 8 wk. Then all bulls were exposed to 23 C for 8 wk. Bulls were fed so that both control and stressed bulls gained at similar rates (.58 kg/d). Semen was collected with an artificial vagina twice weekly before, during and after heat stress. During treatment, the respiratory rate of stressed bulls was greater (P less than .001) than that of control bulls (54.2 +/- 1.5, 29.9 +/- 1.5 breaths/min, respectively). Rectal temperatures were increased (P less than .01) from 38.2 +/- .1 to 38.7 +/- .1 C and water consumption was increased by 35% in stressed bulls when compared with controls. Semen volume was not altered by treatment, but percentage of motile sperm decreased (P less than .01) in stressed bulls by 2 wk after the start of heat treatment. Sperm motility of stressed bulls returned to normal values 8 wk after the end of heat treatment. Similarly, the percentage of aged acrosomes on sperm from stressed bulls increased (P less than .01) by the second week of treatment and remained greater than that of controls throughout the stress period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Morphologic characterization of specific granules in Greyhound eosinophils

BACKGROUND: "Vacuolated" eosinophils (ie, eosinophils with empty, nonstaining granules) have been described previously in normal Greyhounds. However, to our knowledge, detailed studies of granules in vacuolated and normal eosinophils in this breed have not been performed. OBJECTIVE: The objective of this prospective study was to characterize some of the morphologic, ultrastructural, and cytochemical staining features of specific (primary) granules in both normal and vacuolated eosinophils in Greyhound blood. METHODS: Morphologic features of eosinophils in Wright's- and Diff-Quik-stained peripheral blood smears from 49 Greyhounds were compared with 200 blood smears from non-Greyhound dogs. Transmission electron microscopy was done on blood from 3 Greyhounds with vacuolated eosinophils and 3 with normal eosinophil granules. Blood smears from 4 of these dogs also were stained cytochemically with alkaline phosphatase (AP), chloracetate esterase (CAE), and alpha naphthyl butyrate esterase (ANBE). The morphologic features and tinctorial properties of vacuolated and normal eosinophils were compared. RESULTS: Twenty-six Greyhounds (53%) had vacuolated eosinophils and 23 (47%) had normal granulated eosinophils in smears stained with Wright's stain. Only 1% of eosinophils were vacuolated in non-Greyhound dogs. Twenty of the 23 (85%) Greyhounds with normal granulated eosinophils on Wright's-stained smears had vacuolated eosinophils in smears stained with Diff-Quik. Ultrastructurally, no morphologic differences were observed between granules of vacuolated and normal eosinophils. Both vacuolated and normal eosinophils in Greyhounds were positive for AP and negative for CAE and ANBE, as expected for normal dogs. CONCLUSION: Vacuolated eosinophils in Greyhounds likely reflect, at least in part, differential staining properties of the specific granules with different hematologic stains. Ultrastuctural and cytochemical features of eosinophil granules were similar in normal and vacuolated eosinophils from Greyhounds.     

旋毛虫死活快速鉴别的实验研究

为了寻找快速鉴别旋毛虫死活的染色方法。用0．03％美蓝、美蓝-伊红-硼砂染液(M．E．B)和1％中性红3种染液，对死或活旋毛虫幼虫和成虫进行染色。结果3种染液均能使死亡旋毛虫幼虫在1分钟内着色，活虫则不着色。3种染液对旋毛虫死、活成虫均不着色。结论认为3种染液染色均可快速鉴别旋毛虫幼虫死活。     

SEMEN COLLECTION AND EVALUATION IN THE RAM: The Preparation of Spermatozoa for Morphological Examination

Tail and mid-piece morphology of ram spermatozoa were compared using wet preparations of semen diluted in buffered formal saline at temperatures of 10 degrees C and 65 degrees C. The temperature of the diluent did not affect the occurrence of abnormalities. Tail and mid-piece morphology were also examined in semen smears stained by a modified Williams' stain using glass slides at temperatures of 10 degrees C, 38 degrees C and 65 degrees C. The occurrence of the abnormalities was not affected by the slide temperature. The occurrence of tail and mid-piece abnormalities was compared using the 2 methods of preparation. Only the occurrence of distal cytoplasmic droplets was affected by the method of preparation. In the stained smear preparations, most of the distal cytoplasmic droplets were lost. However, only a few of the proximal droplets were lost when this method was used.     

The Effects of Hoechst 33342 Staining and the Male Sample Donor on the Sorting Efficiency of Canine Spermatozoa

The aim of this study was to evaluate the influence of Hoechst 33342 (H‐42) concentration and of the male donor on the efficiency of sex‐sorting procedure in canine spermatozoa. Semen samples from six dogs (three ejaculates/dog) were diluted to 100 × 10⁶ sperm/ml, split into four aliquots, stained with increasing H‐42 concentrations (5, 7.5, 10 and 12.5 μl, respectively) and sorted by flow cytometry. The rates of non‐viable (FDA+), oriented (OS) and selected spermatozoa (SS), as well as the average sorting rates (SR, sorted spermatozoa/s), were used to determine the sorting efficiency. The effects of the sorting procedure on the quality of sorted spermatozoa were evaluated in terms of total motility (TM), percentage of viable spermatozoa (spermatozoa with membrane and acrosomal integrity) and percentage of spermatozoa with reacted/damaged acrosomes. X‐ and Y‐chromosome‐bearing sperm populations were identified in all of the samples stained with 7.5, 10 and 12.5 μl of H‐42, while these two populations were only identified in 77.5% of samples stained with 5 μl. The values of OS, SS and SR were influenced by the male donor (p < 0.01) but not by the H‐42 concentration used. The quality of sorted sperm samples immediately after sorting was similar to that of fresh samples, while centrifugation resulted in significant reduction (p < 0.05) in TM and in the percentage of viable spermatozoa and a significant increase (p < 0.01) in the percentage of spermatozoa with damage/reacted acrosomes. In conclusion, the sex‐sorting of canine spermatozoa by flow cytometry can be performed successfully using H‐42 concentrations between 7.5 and 12.5 μl. The efficiency of the sorting procedure varies based on the dog from which the sperm sample derives.     

Breeding soundness examination of yearling beef bulls

Yearling beef bulls were subjected to a breeding soundness examination (BSE) at completion of performance testing programs at 4 locations over 5 years. Of 862 bulls, 80.1% were classified as satisfactory potential breeders, 7.3% as questionable potential breeders, and 12.7% as unsatisfactory potential breeders. Year (P less than 0.01), location (P less than 0.01), and breed (P less than 0.01) affected the percentage of bulls classified as satisfactory; age of the bulls did not affect this percentage. Adjusted mean scrotal circumference (SC) measurements were 31, 33.2, and 34.8 cm for bulls classified as unsatisfactory, questionable, and satisfactory (P less than 0.01), respectively. Of 109 bulls classified as unsatisfactory, 2.8% were so classified because of poor semen quality alone; 41.3% had no ejaculate in 4 separate electroejaculation attempts. Other abnormalities in these 109 bulls included reproductive tract infections (22%), persistent penile frenulum (16.5%), testicular abnormalities (8.3%), fibropapilloma (1.8%), hernia (1.8%), aplastic epididymis (1.8%), penile abnormalities (1.8%), pendulous sheath (0.9%), and eye abnormalities (0.9%). Age had a significant effect on SC in bulls at 3 locations and on percentage of normal cells, primary abnormalities, and secondary abnormalities as well as BSE score at 1 location. Percentage of primary and secondary abnormalities as well as SC were different across years at 2 locations, and percentage of normal and motile cells as well as BSE score were different across years at 1 location. Breed effects were significant for SC, percentage of primary abnormalities, and BSE score at 3 locations and for percentage of normal and motile cells at 1 location.     

Associations among age, scrotal circumference, and proportion of morphologically normal spermatozoa in young beef bulls during an initial breeding soundness examination.

OBJECTIVE: To evaluate age and scrotal circumference as predictors of semen quality in young beef bulls. DESIGN: Cohort study. ANIMALS: 1,173 beef bulls < 15 months old. PROCEDURE: During initial breeding soundness examination, variables for bulls producing > or = 70% morphologically normal spermatozoa were compared with those for bulls producing < 70% morphologically normal spermatozoa. Mean and 95% confidence interval for age and scrotal circumference were constructed to detect differences between groups of bulls over all observations and within the 5 most common breeds. For these 5 breeds, chi 2 analysis was used to evaluate differences in the proportion of bulls that had values less than the population mean for scrotal circumference, age, and percentage of morphologically normal spermatozoa. Multivariate regression was used to quantify variation in the proportion of morphologically normal spermatozoa that could be explained by age and scrotal circumference. RESULTS: Mean (+/- SD) age and scrotal circumference differed significantly for bulls that produced > or = 70% morphologically normal spermatozoa (12.7 +/- 1.1 months and 35.6 +/- 2.7 cm) and bulls that produced < 70% morphologically normal spermatozoa (12.1 +/- 1.2 months and 34.8 +/- 3.3 cm). The proportion of bulls younger than mean age at first examination and the proportion producing > or = 70% morphologically normal spermatozoa differed among breeds. Age and scrotal circumference explained only 11% of the variation in semen quality. CLINICAL IMPLICATIONS: Among young beef bulls, those that were older and had larger testes were more likely to produce > or = 70% morphologically normal spermatozoa. Age and scrotal circumference were not sufficient predictors of semen quality.     

Effect of group thawing on post-thaw viability of bovine spermatozoa packaged in .5-milliliter French straws

The objective of this study was to determine the effects of thawing groups of 2, 5, 10, 15, or 20 .5-ml French straws on post-thaw spermatozoal viability. Thermostatically controlled and nonthermostatically controlled thawing baths were compared. Using a split-plot design, semen from 10 bulls was extended in egg yolk citrate, frozen, and then thawed (in the respective groups) at 36 degrees C in two types of thawing baths. Motility and percentage of intact acrosomes were determined immediately after thawing (0 h) and again after 4 h of incubation at the respective temperature of each thawing bath. Neither percentage of intact acrosomes nor motility was influenced by the number of straws thawed at 0 h (P greater than .05). Thawing bath had no effect (P greater than .05) on motility or percentage of intact acrosomes at 0 h. Bull variation was significant in both the 0- and 4-h evaluations. After 4 h of incubation, there was a significant (P less than .05) straw number x thawing bath interaction. When 15 or 20 straws were thawed in the thermostatically controlled bath there was a reduction (P less than .05) in motility and percentage of intact acrosomes. However, in the nonthermostatically controlled bath there was no reduction in motility and percentage of intact acrosomes as the size of straw group increased. Our results indicate that, when using a nonthermostatically controlled thawing bath, semen packaged in .5-ml straws can be thawed in groups of 20 without an effect on post-thaw sperm viability.     

Single-step technique for staining Anaplasma marginale in bovine blood smears.

Three available differential stains, Camco-Quik, Diff-Quik, and Wright-Giesma were compared for detection of intraerythrocytic Anaplasma marginale in bovine blood smears. In samples where < 1% to more than 51% of the RBC were infected, statistical analysis of the data indicated no significant difference in the detection of A marginale with Camco-Quik or Diff-Quik stains. However, a significantly lower percentage of infected RBC were detected when blood smears were stained with the Wright-Giemsa stain, compared with the other 2 methods.     

Numbers of Sertoli cells, quantitative rates of sperm production, and the efficiency of spermatogenesis in relation to the daily sperm output and seminal quality of young beef bulls

Data from 34 yearling Hereford or Angus bulls were used to investigate relationships of testicular size, quantitative rates of sperm production, Sertoli cell numbers, numbers of germ cells supported per Sertoli cell, and the efficiency of spermatogenesis to daily sperm output and seminal quality. Two ejaculates were collected by electroejaculation from each bull on each of 2 days/week throughout the study. The percentage of progressively motile sperm and the percentage of morphologically normal sperm were determined from aliquots of fresh semen. Additional aliquots of semen were frozen in glass ampules or plastic straws and subsequently evaluated for postthaw motility and percentage of sperm with intact acrosomes. Sertoli cell numbers, the numbers of germ-cells per Sertoli cell, and the efficiency of spermatogenesis were unrelated to the quality of fresh or frozen semen (P greater than 0.05). In first ejaculates, the numbers of sperm and motile sperm were related (P less than 0.05) to testicular parenchymal weight (r = 0.38 and 0.50), daily sperm production (r = 0.45 and 0.53), and spermatids per gram of testicular parenchyma (r = 0.35 and 0.34). Testicular parenchymal weight and daily sperm production also were related to daily sperm output and to the average daily motile sperm output of these bulls (P less than 0.05), but could account for less than 25% of the variability in these end points among bulls.     

Passage of exogenous L-thyroxine and triiodothyronine into bovine ejaculate

The metabolic effects of thyroxine (T4) and triiodothyronine (T3) on spermatozoa metabolism and male anatomy have been demonstrated. The metabolic effects of T3 and T4 could affect the physiologic characteristics of the spermatozoa. There are little data on the passage of T4 and T3 into the ejaculate from blood. The passage of exogenous T4 and T3 from the blood into semen was measured after T4 (45 mg) or T3 (37.5 mg) was injected IV into 8 bulls. Blood and electroejaculate were obtained simultaneously at 20, 40, 60, 120, and 180 minutes and 24 hours after bulls were injected to determine T3 and T4 concentrations compared with base-line values. Blood T3 and T4 concentrations were increased (P less than 0.05) at 20 minutes after bulls were injected (1.1 +/- 0.25 to 598 +/- 76.3 ng/ml and from 66 +/- 5 to 1,318 +/- 105 ng/ml, respectively). Seminal concentrations of T4 were unchanged until 120 minutes after bulls were injected, when they increased (P less than 0.05) from less than 1.2 ng/ml to 4.7 +/- 1.9 ng/ml. However, seminal concentrations of T3 were increased (P less than 0.05) from less than 0.1 ng/ml to 0.5 +/- 0.2 ng/ml at 20 minutes and to 12.5 +/- 2.9 ng/ml at 120 minutes after bulls were injected. It was concluded that exogenous thyroid hormones passed into the ejaculate from blood, with T3 passing faster than T4.