Morphometric analysis of llama (Lama glama) sperm head

Use of commercial extenders, with and without the addition of egg yolk, for cooling llama semen

The objective of this study was to evaluate the effect of two commercial extenders, AndroMed® (AM) and Androstar® Plus (AS) both with and without the addition of egg-yolk (EY), for cooling llama semen. A total of sixteen ejaculates were collected from four males. Each ejaculate was divided into four aliquots and diluted with: AM, AM with 20 % EY (AM-EY), AS and AS with 20 % EY (AS-EY) and then cooled to 5 °C in an Equitainer®. Evaluations were carried out in raw semen, after dilution (0 h) and after 24 and 48 h of cooling. Data were analysed using either Friedman or ANOVA. Although total motility decreased in all cooled samples compared to the corresponding 0 h (P < 0.05), the highest percentages were observed in AM-EY being significantly higher than all other cooled samples after 24 h and higher than AS and AS-EY after 48 h. No significant differences were observed in the percentages of live acrosome-intact sperm between extenders at all times tested. A significant decrease in the percentage of sperm membrane osmotic function was observed in samples cooled with AS and AS-EY after 24 and 48 h vs. raw semen and in AM 48 h vs. raw semen. Finally, a significant increase in the percentage of sperm with abnormal tails was observed in the samples cooled with AS and AS-EY. Of all the extenders used, AndroMed® could be considered an option for cooling llama semen and the addition of EY to this extender improves its effectiveness. DATA AVAILABILITY: The data that support the findings of this study are available from the corresponding author upon reasonable request.

Comparative ejaculatory response, fresh and frozen semen quality and fertility to artificial vagina vs electroejaculation method of semen collection in mithun (Bos frontalis) bulls

The study aimed to describe a comparative ejaculatory response, fresh and frozen-thawed semen quality and fertility of semen collected by artificial vagina and electroejaculation in mithun. Experimental bulls were divided into two groups, G-I: young bulls (n = 4; 4-5 years of age) and G-II: older bulls (n = 4; 8-10 years of age). Sixteen ejaculates were collected from each group G-I (AV₁ ) and G-II (AV₂ ) by artificial vagina method (control). Thirty-six ejaculates were collected from the same bulls from each group G-I (EE₁ ) and G-II (EE₂ ) by electroejaculation method (treatment). The study did not reveal any significant (p > 0.05) difference in the ejaculatory responses between EE₁ and EE₂ . Mann-Whitney U test indicated that salivation discomfort sign score was significantly (p < 0.05) higher in EE₁ . Fresh and frozen-thawed semen quality parameters, and motility and velocity profiles recorded by computer-assisted sperm analyser were significantly (p < 0.05) lower in electroejaculation than the artificial vagina. The conception rates (AV₁ vs EE₁ & AV₂ vs EE₂ ) at day 35-45 post insemination were nonsignificantly higher (p > 0.05) in the artificial vagina group. It concluded that, although artificial vagina method has better semen quality, nevertheless, electroejaculation has the potential for semen collection from free-range mithun bulls to incorporate in assisted reproductive technology procedures.

Use of dimethylformamide to cryopreserve alpaca semen previously incubated with collagenase

The objective of this study was to evaluate the effect of collagenase and two final dimethylformamide (DMF) concentrations (4% and 7%) on alpaca frozen-thawed sperm quality. A total of 25 ejaculates from 5 alpaca were obtained using electroejaculation. Each individual ejaculate was evaluated and then diluted 4:1 in a solution of 1 mg/ml collagenase in HEPES-TALP medium and incubated for 4 min at 37°C. Subsequently, samples were diluted in TRIS-fructose-citric acid-egg yolk and cooled to 5°C. Then, each sample was divided in two aliquots and DMF at final concentration of 4% or 7% was added, equilibrated for 1 hr at 5°C and frozen over liquid nitrogen vapours. A Kruskal-Wallis test was used to evaluate the sperm morphometry, and Completely Random Block designs were used to analyse sperm motility, viability, membrane function and acrosome status. After collagenase incubation, none of the samples showed thread formation, and sperm parameters were preserved. Non-progressive motile sperm were higher (p < .05) in equilibrated samples (4% DMF: 31.8 ± 8.3% and 7% DMF: 36.3 ± 11.8%) compared to raw (10.1 ± 4.3%) and frozen-thawed semen (4% DMF: 9.7 ± 1.8% and 7% DMF: 7.5 ± 3.2%). Sperm membrane function, membrane integrity and intact acrosomes were higher (p < .05) in raw semen (40.1 ± 12.2%, 94.6 ± 3.2% and 91.3 ± 8.1%) compared to frozen-thawed samples (4% DMF: 19.8 ± 4.7%, 53.2 ± 2.7%, 65.7 ± 8.7% and 7% DMF: 20.4 ± 4.5%, 54.1 ± 1.4%, 64.6 ± 9.1%). Length of the sperm head was lower in frozen-thawed samples, being statistically different with 4% DMF compared to pre-freezing samples. The ratio between acrosome and head areas was greater (p < .05) in frozen-thawed samples. Incubation of raw alpaca semen with collagenase decreased the thread formation without affecting sperm quality. Frozen of collagenase treated alpaca semen with 4% or 7% DMF did not preserve the sperm parameters in thawed samples.

Morphology, morphometry and chromatin distribution in llama sperm nuclei

The objectives of this study were as follows: (i) to describe and evaluate the frequencies of different morphologies of llama sperm nuclei, (ii) to determine morphometric values of nuclear parameters, (iii) to describe and estimate the frequencies of different classes of chromatin distribution and (iv) to measure haploid DNA content and analyse its nuclear distribution. The study was performed using ejaculates collected from seven males, and sperm nuclei were stained with the Feulgen reaction. Normal morphology ranged from 78.36% to 93.92%, and abnormalities included short, small, large, pyriform, narrow, micro and round nuclei. Important differences in nuclei considered normal were found between some males. The following average values were obtained for each sperm nuclear morphometric parameter analysed: area 11.64 μm² , perimeter 13.16 μm, length 5.12 μm, width 2.81 μm, ellipticity 1.85 and form 0.83. Differences between males were significant for all the parameters (p < .01). Light microscope observations and cytophotometric determinations allowed discriminating between three classes of chromatin distribution: homogeneous, diffuse and showing a clear band. Significant differences between males were found for the frequencies of the three classes (p < .01). Cluster analysis methods were used to estimate the resemblance between males according to the characteristics of their sperm nuclei. A great intermale variability was found for morphological, morphometric and chromatin distribution data. These parameters would have low dependence between them.

The effects of inbreeding on sperm morphometry of captive-bred endangered mammals

Captive breeding is used for the conservation of endangered species, but inbreeding can result when a small number of founders are used to establish populations. Inbreeding can reduce the proportion of normal sperm in an ejaculate, but may also have effects on sperm size and shape (morphometry). We investigated the effects of inbreeding on sperm morphometry of black-footed ferrets (Mustela nigripes (Audubon and Bachman, 1851)) and red wolves (Canis rufus Audubon and Bachman, 1851) from captive breeding programs to determine if more inbred males produced sperm of poor quality (bulky head, small midpiece, short tail). We measured sperm head length, head width, midpiece length, midpiece width, and tail length on 10 sperm from each male of both species. A negative relationship between variation in sperm tail length and inbreeding coefficient (f) was found in black-footed ferret, suggesting that more inbred individuals will have reduced genetic and phenotypic variation. Analyses indicated a negative relationship between sperm head width and f and a positive relationship between sperm tail length and f in red wolf, suggesting that more inbred male red wolves could have faster sperm. These results indicate that inbreeding affects functionally important aspects of sperm morphometry, but that these effects may not be entirely negative.

Assessment of spermatozoa in fertile alpaca (Vicugna pacos) males: Study of sperm head morphometry using a nonautomated digital method and sperm morphology based on strict criteria

Although computer-assisted systems for sperm morphometry and morphological analysis are important tools in the study of male fertility, their use in extensive systems in alpacas is limited by factors such as the expense of equipment and the high altitudes of the Andean region. The objectives of this study were to evaluate alpaca sperm head morphometry using a nonautomated digital method and determine the frequency of sperm abnormalities based on strict criteria for sperm morphology in fertile male alpacas. Ejaculates (n = 15) from seven alpacas were collected, and sperm smears stained with modified Papanicolaou were processed. For morphometric analysis, 3,000 sperm (200 cells/sample) images were captured at 400× magnification and Quick Photo MICRO 3.0 software was used for manual measurement of basic (sperm head length, width, perimeter and area) and derived variables (ellipticity, shape factor, elongation and regularity). For morphology assessment, smears were observed at 1000× magnification according to WHO and strict criteria. Average morphometric parameters were length 5.48 μm, width 2.99 μm, perimeter 13.62 μm, area 12.43 μm² , ellipticity 1.86, shape factor 1.20, elongation 0.29 and regularity 1.05. Significant between-individual and within-individual differences were found in morphometric parameters. Based on morphometric study, sperm heads were classified as elliptical or normal (49%), long (18%), short (2%), pyriform (12%), round (9%), large (6%) and small (4%). Morphological analysis found no additional sperm head defects in 49% of normal sperm obtained by morphometry, although a 4% incidence of neck/mid-piece defects and a 16% incidence of principal-piece defects were found. We conclude that sperm head morphometry assessment in fertile alpacas using a nonautomated digital method is feasible, and that defects in sperm heads constitute the main morphological alteration (>50% of the sperm population), based on WHO and strict criteria.