Comparison between the Sperm Morphology in Semen Samples Obtained from Yearling Beef Bulls by Transrectal Massage of the Ampullae and Cauda Epididymal Dissection

As electroejaculation (EEJ) is prohibited for use on unanaesthetized animals in Sweden, there is a need for an alternative method of semen collection from bulls in the field. The aim of the present study was to evaluate the use of transrectal massage (TM) of the ampullae to collect semen from yearling beef bulls under field conditions in Sweden. Transrectal massage was performed on 52 yearling beef bulls. Volume of semen collected, duration of procedure, percentage progressively motile sperm, and sperm concentration were measured. Smears were prepared for sperm morphology examination. Semen samples were obtained from 47 of 52 bulls. Mean volume was 3.2 ml (SD +/- 3.7), mean duration of collection was 7.4 min (SD +/- 2.8), mean percentage progressively motile sperm was 43.5% (SD +/- 29.2) and mean concentration was 201.9 x 10(6) spermatozoa/ml (SD +/- 278 x 10(6)). Twenty-three of the 52 bulls were slaughtered 3-4 days after semen collection and aliquots of the cauda epididymal contents were collected for sperm morphology examination. The percentages of proximal droplets, abnormal tails and abnormal midpieces were significantly higher (p < 0.05) and the percentage of detached heads was significantly lower (p < 0.05) in the post-mortem samples compared with those in the TM samples. However, importantly there was no significant difference between the two sample types in the percentages of abnormal heads. This study demonstrates that semen can be collected from yearling beef bulls by TM. We think that TM constitutes a useful tool, when semen collection with EEJ or artificial vagina (AV) is not possible under field conditions, when included in the bull breeding soundness evaluation (BBSE) protocol. However, further studies are needed, and presently being carried out, to evaluate if semen samples collected by TM are comparable with semen samples collected by AV.     

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.     

The proportion of beef bulls in western Canada with mature spermiograms at 11 to 15 months of age

A study was conducted to determine the proportion of yearling beef bulls that have mature spermiograms at 11 to 15 months of age, and to evaluate the relationship between semen quality traits, age, and scrotal circumference. Semen samples and data on sperm motility and scrotal circumference measurements were obtained from 1641 bulls of 14 breeds. Criteria for a satisfactory spermiogram included sperm concentration > or = 400 x 10(6)/mL, > or = 60% progressively motile sperm, and > or = 70% morphologically normal sperm. The mean scrotal circumference measurements for all bulls combined were 33.4, 34.4, 35.2, 35.8, and 35.3 cm at 11, 12, 13, 14, and 15 months of age, respectively. The percentage of bulls with matures spermiograms at 11, 12, 13, 14, and 15 months of age were 20%, 30%, 51%, 52%, and 61%, respectively. There was a high positive correlation (r = 0.9) between the number of bulls with > or = 70% normal sperm and scrotal circumference measurement. The main types of morphologic defects observed in immature bulls were proximal droplets and midpiece defects.     

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.     

Severe sperm abnormalities with subsequent recovery following on scrotal oedema and posthitis in a Bulldog

A 5-year-old Bulldog was examined for breeding soundness 6, 10 and 26 weeks after suffering from a posthitis, which extended caudally to include the scrotum. On first semen examination, Spermac-stained smears examined under the light microscope showed that 50 per cent of the spermatozoa had abnormal heads, and a further 20 per cent had other abnormalities. On second examination, the head abnormalities were reduced to 38 per cent, although the total abnormality count was 92 per cent. The various abnormalities noted with the light microscope were confirmed by the transmission electron micrographs, which revealed a variety of bizarre head abnormalities, diadem defects, acrosomal cysts and Dag defects. Between the second and third examinations the dog sired a litter of six pups, and on third examination had a normal spermiogram.     

Sperm morphology in Estonian and Tori breed stallions

The standard procedure for assessing the breeding potential of a stallion includes the parameter total number of spermatozoa classified as morphologically normal. This study investigated sperm morphology of fresh semen in randomly chosen Estonian (E, n = 8) and Tori (T, n = 7) breed stallions with proven fertility. Two ejaculates were examined from each stallion. An aliquot from each ejaculate was fixed in 1 mL formol-saline immediately after collection and examined with phase-contrast microscope at a magnification 1000x for all types of morphological abnormalities. Furthermore smears were prepared and stained according to Williams (carbolfuchsin-eosin) for a more detailed examination of the sperm heads with light microscope at a magnification 1000x. Analysis of variance was applied to the data, and results are presented as LSmeans (+/- SE). One T stallion that had a disturbance in the spermatogenesis and one 22-year-old E stallion were not included in the analyses. The T stallions had on average 57.5 +/- 4.1% and the E-stallions 74.4 +/- 3.8% morphologically normal spermatozoa (p = 0.012). In 4 of 7 T stallions and 7 of 8 E stallions both ejaculates had > 50% morphologically normal spermatozoa. There was a significant difference between breeds in mean percentage of proximal droplets (17.3 +/- 2.7% and 2.9 +/- 2.5% for T and E stallions, respectively; p = 0.003).     

Changes in Mithun (Bos frontalis) spermatozoa during epididymal passage

Genital organs of 10 healthy, adult Mithun bulls (6-8 years old) that were slaughtered at the dwellings of tribal people for meat were collected. Immediately after collection, spermatozoa from 3 different regions of the epididymis, i.e. the head, body and tail, were obtained to study morphological changes of the spermatozoa during passage through these regions. The prevalence of proximal cytoplasmic droplets significantly decreased from the head to the tail of the epididymis. Conversely, the percentage of distal cytoplasmic droplets increased significantly from the head to the tail region. The incidence of tailless heads rose significantly from head to body and then reduced significantly in the tail region. The percentage of total head abnormalities did, however, not change markedly, but total mid-piece and tail abnormalities differed significantly between the three epididymal regions.     

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.     

Assessment of the morphology of frozen-thawed bull sperm in relation to its cryopreservation for artificial insemination

The morphology of sperm in raw semen was compared with that of the live sperm in semen which had been frozen and thawed. The thawed semen was stained with 6-carboxyfluorescein diacetate and propidium iodide and examined by fluorescence microscopy; smears of the raw semen were stained with eosin and nigrosin. Thirty-four ejaculates from 24 bulls of various breeds were examined. There were fewer abnormal heads, detached heads, coiled tails and proximal cytoplasmic droplets/pseudodroplets in the thawed semen than in the raw semen, there was no change in the number of bent tails, but the number of distal cytoplasmic droplets/pseudodroplets increased. There were no significant differences in morphology between ejaculates which passed or failed the osmotic resistance test after thawing, but failed batches tended to have more distal cytoplasmic droplets/pseudodroplets.     

Evaluation of bovine spermatozoal morphologic features after staining or fixation.

Two experiments were conducted to evaluate effects of 3 stains and 2 fixatives on morphologic features of bovine spermatozoa. In experiment 1, the morphologic features of acrosomes of raw and incubated, extended spermatozoa were evaluated after staining with Hancock's Blom's or Wells-Awa's stains or after fixation with buffered glutaraldehyde. Evaluations were done of stained smears by bright field microscopy and of fixed, unstained preparations, by differential interference contrast microscopy, using wet mounts. Raw semen samples from 1st ejaculates of 80 bulls were evaluated. The percentage of spermatozoa with intact acrosomes averaged 83.5% in unstained preparations fixed in glutaraldehyde, compared with averages of 68.1, 74.5, and 67.4% for smears stained with Hancock's, Blom's, or Wells-Awa's procedures (P less than 0.01). From these results, it appeared that procedures for preparing stained smears were detrimental to acrosomes. Although counts for other acrosomal abnormalities differed (P less than 0.01) in each treatment, patterns were inconsistent. With incubated, extended spermatozoa from 57 bulls, glutaraldehyde-fixed, unstained samples had more (55%) intact acrosomes (P less than 0.01) than did samples stained with Hancock's or Blom's procedures (24.0 and 34.7%, respectively, but the former were not significantly different from Wells-Awa-stained smears (49.3% intact acrosomes). In experiment 2, several morphologic characteristics of spermatozoa from 15 1st ejaculates of 7 bulls were evaluated after staining with Hancock's or Blom's stains or after fixation in buffered glutaraldehyde or buffered formal saline fixatives. Higher counts (P less than 0.01) of head abnormalities were found in wet, unstained fixed preparations (4.83, 4.47, 7.87, and 7.93% respectively, for Hancock's, Blom's, glutaraldehyde, and formol saline methods). There were more (P less than 0.05) separated heads on stained, dry smears (1.43, 1.23, 0.47, and 0.47%, respectively, for Hancock's, Blom's, glutaraldehyde, and formol saline procedures). Fixation with buffered glutaraldehyde resulted in higher counts (P less than 0.01) of proximal protoplasmic droplets (2.47, 1.03, 0.67, and 1.43%, respectively, for glutaraldehyde, Hancock's, Blom's, and formol saline procedures). Although not significant, the same trend was observed for distal protoplasmic droplets...     

Sperm Morphology in the Domestic Cat, and its Relation with Fertility: A Retrospective Study

Knowledge about normal ranges in semen quality and the association between sperm morphology and fertility in felids is limited. The aims of this retrospective study were to (1) define a normal spermiogram in cats; (2) evaluate possible effects of season, age and breed on sperm morphology; and (3) evaluate the relationship between sperm morphology and fertility. Semen samples collected by electroejaculation from 52 cats were evaluated for sperm morphology. The cats constituted two groups: a general population of cats (n = 48) and cats examined because of poor breeding records (n = 4). The general population was divided into household (n = 20), pedigree (n = 19) and colony cats (n = 9) and into three age classes, <12 months, 12-59 months and >or=60 months. The median percentage of normal spermatozoa in the general population was 44.0% (range 1.0-91.0%). Criteria were tentatively set for what was considered a normal spermiogram. The mean percentage of normal spermatozoa was higher during February to July than during August to January (p < 0.05). Pedigree cats had a lower mean percentage of normal spermatozoa than did household cats (p < 0.05). Age had no effect on the percentage of normal spermatozoa but was positively correlated with the percentage of proximal droplets. Of the cats with <40% normal spermatozoa (n = 19), all those with known breeding records (n = 11) had produced litters. The four cats examined because of poor breeding results had higher percentages of different sperm abnormalities than tentatively stipulated for the normal spermiogram. In two of these cats both sperm morphology and fertility changed over time.     

Genetic parameter estimates for scrotal circumference and semen characteristics of Line 1 Hereford bulls

The objectives of this study were to estimate heritability for scrotal circumference (SC) and semen traits and their genetic correlations (rg) with birth weight (BRW). Semen traits were recorded for Line 1 Hereford bulls (n = 841), born in 1963 or from 1967 to 2000, that were selected for use at Fort Keogh (Miles City, MT) or for sale. Semen was collected by electroejaculation when bulls were a mean age of 446 d. Phenotypes were BRW, SC, ejaculate volume, subjective scores for ejaculate color, swirl, sperm concentration and motility, and percentages of sperm classified as normal and live or having abnormal heads, abnormal midpieces, proximal cytoplasmic droplets (primary abnormalities), bent tails, coiled tails, or distal cytoplasmic droplets (secondary abnormalities). Percentages of primary and secondary also were calculated. Data were analyzed using multiple-trait derivative-free REML. Models included fixed effects for contemporary group, age of dam, age of bull, inbreeding of the bull and his dam, and random animal and residual effects. Random maternal and permanent maternal environmental effects were also included in the model for BRW. Estimates of heritability for BRW, SC, semen color, volume, concentration, swirl, motility, and percentages of normal, live, abnormal heads, abnormal midpieces, proximal cytoplasmic droplets, bent tails, coiled tails, distal cytoplasmic droplets, and primary and secondary abnormalities were 0.34, 0.57, 0.15, 0.09, 0.16, 0.21, 0.22, 0.35, 0.22, 0.00 0.16, 0.37, 0.00 0.34 0.00, 0.30, and 0.33, respectively. Estimates of rg for SC with color, volume, concentration, swirl, motility, and percentages of live, normal, and primary and secondary abnormalities were 0.73, 0.20, 0.77, 0.40, 0.34, 0.63, 0.33, -0.36, and -0.45, respectively. Estimates of rg for BRW with SC, color, volume, concentration, swirl, motility, and percentages live, normal, and primary and secondary abnormalities were 0.28, 0.60, 0.08, 0.58, 0.44, 0.21, 0.34, 0.20, -0.02, and -0.16, respectively. If selection pressure was applied to increase SC, all of the phenotypes evaluated would be expected to improve. Predicted correlated responses in semen characteristics per genetic SD of selection applied to SC were 0.87 genetic SD or less. If selection pressure was applied to reduce BRW, the correlated responses would generally be smaller but antagonistic to improving all of the phenotypes evaluated. Predicted correlated responses in SC and semen characteristics per genetic SD of selection applied to BRW were less than 0.35 genetic SD.     

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.     

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.     

The Effects of Trypanosomosis on Sperm Morphology in Zebu×Friesian Crossbred Bulls

Detailed studies of sperm morphological abnormalities were carried out on 12 Zebu x Friesian crossbred bulls used in a study of the effects of trypanosomosis. Four bulls were infected with T. vivax, another four with T. congolense, while four served as controls. The infected bulls developed chronic trypanosomosis. All the bulls initially had very low sperm morphological abnormalities that were within acceptable limits for fertile animals. After infection there was a rapid and progressive increase in all sperm abnormalities. Spermatozoa of infected bulls were highly deformed with multiple morphological defects. Mean percentage pre-infection baseline values prior to infection for acrosomal, sperm-head, detached heads, proximal cytoplasmic droplets, distal cytoplasmic droplets, sperm-tail, midpiece and total sperm morphological defects ranged between 0.1 +/- 0.1 for acrosomal and 8.3 +/- 3.2 for total morphological abnormalities in the semen of the bulls. All the infected bulls developed sperm morphological abnormalities of more than a mean of 40.0% from the 4th week after infection until the end of the investigation and were considered unfit for breeding. At 7 weeks post-infection (PI) until the end of the study (12 weeks PI), the controls had a mean of less than 5% sperm morphological defects, while the infected bulls had 100%. Mean percentage values of sperm morphological defects throughout the duration of the investigation for control bulls were low and within the normal range for fertile bulls. These values differed significantly (p<0.001) from the elevated values of the infected bulls. The results show that trypanosomosis due to T. vivax or T. congolense infection can render Zebu x Friesian crossbred bulls unfit for breeding within a very short time. The resultant infertility could be of economic importance in trypanosomosis-endemic sub-Saharan Africa where Zebu x Friesian crossbred bulls are kept.     

Sperm Production and Sperm Morphology of Swedish Warmblood Stallions

The present study investigated daily sperm output and sperm morphology of fresh semen in eight Swedish Warmblood stallions aged 5–8 years. They were used for artificial insemination, and their fertility during the breeding season of semen collection exceeded 60% per cycle. One ejaculate of semen was collected daily for 10 consecutive days from each stallion. The gel-free volume was measured, and the sperm concentration was assessed with a Bürker chamber. The volume of gel-free fraction was multiplied by the sperm concentration to give the total number of spermatozoa (TSN). Sperm morphology was examined in ejaculates collected on days 2, 5 and 10. An aliquot from each ejaculate was fixed in 1 ml formol–saline immediately after collection and examined under a phase-contrast microscope (magnification 1000×) to assess morphological abnormalities. Furthermore smears were prepared and stained according to Williams (carbolfuchsin–eosin) for a more detailed examination of the sperm heads under a light microscope (magnification 1000×). Analysis of variance was applied to data. Total spermatozoa number decreased progressively during the first 8 days of collection, and daily sperm output (DSO) was calculated as mean TSN of collections on days 8–10, being 6.4 × 10⁹ spermatozoa. The overall percentages of morphologically normal spermatozoa in ejaculates collected on days 2, 5 and 10 were above 70%, being significantly lower in ejaculate 2 (68.6%) compared with ejaculates 5 and 10 (72.9% respectively 75.3%).     

Case Study: Relationships of Scrotal Circumference and Scrotal Volume to Growth and Semen Traits in Beef Bulls

Breeding soundness examinations (BSE) were performed on 327 bulls at three locations in Wyoming and Montana. Scrotal circumference (SC), scrotal volume (SV), and body condition score (BCS) data were also collected. The animals were classified as yearlings, 2-yr-olds, or mature bulls. Age class and BCS had significant (P<0.01) effects on SC. Age class also accounted for significant (P<0.01) variation in SV. The correlation between SC and SV was 0.88. Scrotal circumference, SV, and pelvic area (PA) were measured and adjusted for age on the 139 yearling bulls at Location 1 (MT) to allow comparison with other age-adjusted traits. The linear regression of SC on age was 0.023 cm/d (P<0.05). Scrotal circumference and age were significant (P<0.01) sources of variation for the percentage of motile sperm (MOT). Composite yearling bulls had larger (P<0.05) adjusted SV, adjusted SC, pelvic height (PH), and percentage of MOT than Red Angus yearling bulls. The simple correlation between adjusted SC and adjusted yearling BW was 0.33 (P<0.05). Actual SC and SV were positively correlated with actual BW, actual hip height (HH), and percentage of MOT. Scrotal volume and percentage of MOT were positively correlated (0.22) (P<0.05). Our results indicate that SV could be used interchangeably with SC as a measure of sperm- producing capacity in beef bulls. Results of this study indicate that selecting bulls with larger SC or SV should result in increased yearling BW, greater PA, and bulls with improved fertility.     

Morphological and Ultrastructural Studies of Moose Spermatozoa

Epididymal spermatozoa from moose were studied in phase contrast, light interference and electron microscope. Some samples taken from cauda were diluted and frozen in liquid N₂. The motility of the sperms after thawing was good.The concentration of spermatozoa in cauda was calculated to 10 × 10⁶ cells per µl.Morphologically the spermatozoa of moose were found to be quite similar to those collected from bulls. The length of the sperm head was found to be approx. 8.8 µ and the average maximal width 5.2 µ. The average length of the tail was 54.7 µ and the entire length of the spermatozoon varied from 60 to 64 µ. Compared with sperm cells from bulls the moose spermatozoa appeared to have a somewhat shorter and broader head and a slightly shorter tail.The migration of the cytoplasmatic droplets, which was found to be completed in caput, seemed to follow the same pattern as in bulls and boars. As found in these species there was also in the moose a higher frequency of secondary abnormalities in the spermatozoa from cauda than in those from the other parts of epididymis.Studies of the fine structure of the moose spermatozoa seemed to indicate that these are of the same type as the spermatozoa of bulls, rams and boars. In sagittal sections the sperm head was thin, but in contrast to the sperm cells of the species mentioned above no typical waist-like narrowing in the equatorial region was found. The equatorial segment also seemed to be less arched than in the spermatozoa from bulls, rams and boars. Otherwise, no principal difference was found between ultrastructure of the moose spermatozoa and that of the spermatozoa collected from domestic species.     

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.     

Effects of feeding a multivalent polyclonal antibody preparation on feedlot performance, carcass characteristics, rumenitis, and blood gas profile in Bos indicus biotype yearling bulls

The objective of this study was to evaluate effects of feeding monensin (MON) or a multivalent polyclonal antibody preparation (PAP) against several rumen microorganisms on feedlot performance, carcass characteristics, blood gas profile, and rumenitis of Bos indicus biotype (BT) yearling bulls. The study was designed as a completely randomized design with a 3 × 2 factorial arrangement, replicated 4 times, in which 32 yearling bulls of each of 3 BT evaluated (3-way-cross, TC; Canchim, CC; and Nellore, NE) were fed diets containing either MON at 300 mg·d(-1) or PAP at 10 mL·d(-1) across 3 different periods. No significant (P > 0.10) feed additive (FA) main effects were observed for any of the feedlot performance variables and carcass characteristics with the exception of dressing percentage. Yearling bulls receiving PAP had a decreased (P = 0.047) dressing percentage when compared with yearling bulls receiving MON. Significant (P < 0.05) BT main effects were observed for all feedlot performance variables and carcass characteristics with the exception of kidney-pelvic fat expressed in kilograms (P = 0.49) and LM lipids content (P = 0.45). Crossbred yearling bulls (TC and CC) had greater (P < 0.001) ADG, DMI in kilograms, DMI as % of BW, and improved (P = 0.001) G:F when compared with NE yearling bulls. A tendency (P = 0.072) for a FA main effect was observed for rumenitis scores, in which yearling bulls receiving PAP had lesser rumenitis scores than those receiving MON. When the data were disposed as frequency percentage, 55.6% and 45.7% of the rumens from yearling bulls fed PAP and MON were scored between 0 and 1, respectively (0 = no lesions, 10 = severe lesions). Likewise, a significant BT main effect was observed (P = 0.008), where NE yearling bulls had greater rumenitis scores than those of crossbred yearling bulls (TC and CC). No significant FA main effects were observed (P > 0.10) for any of the fatty acids measured in the subcutaneous adipose tissue, with the exception that yearling bulls receiving MON had greater (P < 0.05) concentrations of palmitic acid (16:0), margaric acid (17:0), docosapentaenoic acid (22:5), and docosahexaenoic acid (22:6) than those yearling bulls receiving PAP. Feeding PAP tended to decrease incidence of rumen lesions and led to similar feedlot performance compared with feeding MON. Thus, PAP is a new technology that presents a possible alternative for ionophores.