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Abstract

The aim of this study was to evaluate the influence of ejaculation time on sperm quality parameters in high performance boars. 447 fresh semen samples were used from 9 boars. The samples were collected by the gloved hand method and the duration of ejaculation in seconds was determined. The ejaculates obtained were divided into three groups based on the ejaculation time and into two categories based on the age of the animals. The sperm volume (using graduated bottles), total number of sperm using a Neubauer chamber, motility and intensity of motion using phase contrast microscopy and spermatic morphology using wet preparation with formaldehyde-sodium citrate solution were all evaluated. All variables were compared regarding the ejaculation time and animal age, and the correlation between these variables and the ejaculation time was also evaluated. Animals with higher ejaculation times were found to have a higher semen volume (P<0.05). A positive correlation (0.56; P<0.001) was observed between ejaculation time and the seminal volume, but correlations were low (P>0.05) with regards to other variables. Animals younger than 15 months old had lower semen volumes and higher sperm counts, as well as altered spermatic morphology (P<0.05) compared with older animals. The ejaculation time was found to be associated with the seminal volume, with little effect on the other variables. In conclusion, an adequate seminal analysis should always be performed to evaluate the fresh boar ejaculate, especially in possible semen donor animals.
Online version is available on: www.grjournals.com
Journal of Animal Science Advances
Influence of Ejaculation Time on Sperm Quality
Parameters in High Performance Boars
Oberlender G., Murgas L. D. S., Zangeronimo M. G., Silva A. C. and Pereira L. J.
J Anim Sci Adv 2012, 2(5): 499-509
OBERLENDER ET AL.
499
J. Anim. Sci. Adv., 2012, 2(5):499-509
Influence of Ejaculation Time on Sperm Quality
Parameters in High Performance Boars
Oberlender G., Murgas L. D. S., Zangeronimo M. G., Silva A. C. and Pereira L. J.
Federal University of Lavras Department of Veterinary Medicine, Division of Physiology and Pharmacology. Lavras, Minas Gerais,
Brazil
Abstract
The aim of this study was to evaluate the influence of ejaculation time on sperm quality parameters in high
performance boars. 447 fresh semen samples were used from 9 boars. The samples were collected by the gloved
hand method and the duration of ejaculation in seconds was determined. The ejaculates obtained were divided
into three groups based on the ejaculation time and into two categories based on the age of the animals. The
sperm volume (using graduated bottles), total number of sperm using a Neubauer chamber, motility and
intensity of motion using phase contrast microscopy and spermatic morphology using wet preparation with
formaldehyde-sodium citrate solution were all evaluated. All variables were compared regarding the ejaculation
time and animal age, and the correlation between these variables and the ejaculation time was also evaluated.
Animals with higher ejaculation times were found to have a higher semen volume (P<0.05). A positive
correlation (0.56; P<0.001) was observed between ejaculation time and the seminal volume, but correlations
were low (P>0.05) with regards to other variables. Animals younger than 15 months old had lower semen
volumes and higher sperm counts, as well as altered spermatic morphology (P<0.05) compared with older
animals. The ejaculation time was found to be associated with the seminal volume, with little effect on the other
variables. In conclusion, an adequate seminal analysis should always be performed to evaluate the fresh boar
ejaculate, especially in possible semen donor animals.
Key words: Boar, libido, reproduction, spermatic alterations
*Corresponding Author: guilherme_oberlender@yahoo.com. br
Received on: 02 May 2012
Revised on: 25 May 2012
Accepted on: 27 May 2012
Online Published on: 28 May 2012
Original Article
ISSN: 2251-7219
INFLUENCE OF EJACULATION TIME ON SPERM QUALITY PARAMETERS …
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J. Anim. Sci. Adv., 2012, 2(5):499-509
Introduction
The monitoring and analysis of the semen
quality and quantity produced by boar is of great
economic importance to swine producers,
becoming a critical issue for the success of
artificial insemination (AI) programs (Vyt et al.,
2008; Smital, 2009; Tsakmakidis et al., 2010;
Broekhuijse et al., 2011; López Rodríguez et al.,
2011). An ejaculate with a large number of high
quality sperm is expected from each semen
collection. However, this optimal situation does
not always occur (Spessatto et al., 2007).
The boar semen can be collected in three parts,
a pre-sperm fraction, where sperm and seminal
vesicle secretions are absent, a sperm-rich fraction
containing approximately 70-80% of the total
sperm, and the post-sperm fraction, which consists
mainly of accessory gland secretions (Glover &
Mann, 1954; Murgas & Zangeronimo, 2004).
Despite the fact that the sperm-rich fraction
contains the greatest number of sperm, the
collection of the post-sperm fraction does not
significantly affect the ejaculate quality. According
to the same authors, the characteristics of
ejaculate/fresh semen are the initial step in quality
control of the AI process, irrespective of the
portion collected. Ultimately, these are the
characteristics that define the suitability of
ejaculates for the production of semen doses of a
required quality (Oberlender et al., 2012).
The impact of the boar on the reproductive
performance of the herd is high, especially if the
male serves many females (Smital, 2009). In turn,
the economic gain from an AI Center primarily
depends on the ability of the boar to produce viable
sperm during his lifetime (Robinson & Buhr,
2005), and this production is limited by the testis
capacity, libido and physical integrity, including
hooves, aplombs and column (Murgas &
Zangeronimo, 2004; Spessatto et al., 2007).
Several studies have indicated that the reproductive
performance and the sperm quality of a boar
depends on the following factors: heritability,
testicular size, nutrition, age, breed, sexual
exploration intensity, collection method, handling
of semen post-collection, temperature,
photoperiod, social environment, sexual behavior
and systemic diseases (Marchev et al., 2003;
Chenoweth, 2005; Smital, 2009).
With respect to sexual behavior, the duration
of time between entering the collection pen and
mounting the dummy, the number of mounts
before ejaculation started, and the duration of time
ejaculating are some of the variables evaluated
with respect to their effects on sperm
characteristics (Cameron, 1985; Levis & Reicks,
2005). On the other hand, despite the numerous
possibilities of evaluation methods, few groups
have studied the influence of sexual behavior on
sperm quality parameters in boars (Alonso et al.,
2011). According to Levis and Reicks (2005),
despite the studies already performed, the current
knowledge of the influence of sexual behavior on
the reproductive performance of boars is far less
than the knowledge regarding the physiology of
sperm production.
The ejaculation time is an example of a sexual
behavior parameter that is able to demonstrate the
libido of the boars (Poto el al., 2000). Males that
have high ejaculation times can be considered to
have good libido, but not necessarily a high quality
of semen (Cameron, 1985). The longer the
duration of semen collection, the more time is
spent on all subsequent processes of analysis and
manipulation of the ejaculate. So, in this case,
there is a greater chance of sperm undergoing
external damage, as a result of environmental
temperature, bacterial contamination by the
environment or the animal itself, or other injuries,
thus leading to possible damage of the sperm
quality (Murgas & Zangeronimo, 2004). It is
essential that the sperm quality is evaluated in
order to verify whether a longer ejaculation time
exerts any influence on the sperm characteristics.
Therefore, this study aims to evaluate the
influence and relationship of the ejaculation time
on parameters of semen quality of high
performance boars, including volume, sperm
count, motility, intensity of motion and
morphological alterations.
Materials and Methods
Place and Animals
This study was performed at the Experimental
Center of Porcine of the Department of Veterinary
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Medicine and Animal Science of the Federal
University of Lavras, Minas Gerais, Brazil. A total
of 447 samples of fresh semen were analyzed from
9 high performance Pietran breed boars, aged
between seven and 25 months. The collection
protocol was started from seven months of age
when males weighed approximately 115.0kg. The
animals were housed in individual pens located in
a shed with a concrete floor and a tiled roof made
of asbestos cement. They were fed with 2.5 to
3.5kg of feed per day and given water ad libitum
through manual drinking fountains like nipples.
Semen Sampling
The semen samples were collected by one
trained and experienced person using the gloved
hand method, with the help of a fixed dummy. The
ejaculates were collected in either a graduated
container, with a capacity of 500 mL, which was
pre-heated to 37°C and protected by and
isothermal container (thermal cup collection)
(Hancock & Howell, 1959). The ejaculation time
was determined from the time when the animal
jumped on the dummy and the collection of semen
began until the completion of the process, which
corresponded to the end of the ejaculation with
posterior penile retraction. The samples were
collected weekly, and the time of its duration was
recorded in seconds.
Quality of the Ejaculates
The ejaculates were collected in their entirety
and evaluated for the routine characteristics of
seminal quality, as detailed below. Samples were
evaluated macroscopically with regards to volume
using the graduated container, smell, by looking
for the presence of urine, blood or other
contaminations and appearance (watery, milky or
milky serum). The motility and intensity of
motion, spermatic count and morphology were
evaluated microscopically.
To assess motility, three subsamples of each
semen sample were placed on warm glass slides
(37°C). The slides were examined under a phase
contrast microscope at a magnification of 400
times. A total of 10 microscopic fields were
assessed to determine the percentage of
spermatozoa with rapid progressive motility and
the intensity of motion. Spermatic motility was
expressed as a progressive motility percentage and
the intensity was classified on a 05 scale, with 5
being the maximum intensity of motion. The
spermatic count was evaluated using a Neubauer
chamber and the total number of sperm in the
entire ejaculate was determined (x109 sperm).
For the evaluation of sperm morphology the
conventional wet preparation technique was used,
wich utilizes a 2.95% formaldehyde-citrate
solution. In this evaluation, about five drops of
fresh semen from each ejaculate were added to
1.0mL of citrate-formaldehyde solution in an
microtube. Next, approximately 10µL of this
solution was placed between the slide and the
coverslip, and observed using phase contrast
microscopy at 1,000 times magnification. The
differential count of 100 spermatic cells was
evaluated, and the percentages of normal sperm
and those with abnormalities were calculated
(Scheid 1993).
Evaluated Groups
The ejaculates collected were first evaluated as
a whole, including all samples from all animals.
Afterwards, based on the study of Alonso et al.
(2011) the ejaculates were divided into three
groups, according to the duration of the semen
collections: Group I (G1) = ejaculation time less
than 360 seconds, Group II (G2) = ejaculation time
between 360 and 420 seconds, and Group III (G3)
= time above 420 seconds. The ejaculates were
also grouped into two categories based on the age
of animals in months: Category I (C1) = animals
under 15 months old (young sexually) and
Category II (C2) = animals over 15 months old
(adults sexually).
Statistical Analysis
All data obtained were represented as means
and standard deviations. A randomized block
design was used on the experimental boars in this
study to compare the data. Two different treatment
sets were used. The first involved three different
treatments: time of ejaculation Groups I, II and
III, and the second included two treatments: age of
the animals Categories I and II.
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For data analysis in these two treatment sets,
all variables, such as age, seminal volume, sperm
count, sperm motility, sperm intensity of motion
and sperm morphology, were submitted to a
normality analysis using the Kolmogorov-Smirnov
test. The data was not found to be normally
distributed (P<0.05), even after data transformation
using the square root option. The treatments in
each set were compared using the Mann-Whitney
test, when there was significance using the
Kruskal-Wallis test (P<0.05). The Spearman’s
correlation test among was performed for all sperm
quality variables compared to the ejaculation
times. All statistical analyses were performed
using the statistical package SPSS for Windows
version 17.0 (SPSS Statistics 17.0, Rel. 17.0.1.
2008, SPSS Inc, Chicago, IL.).
Results and Discussion
The data obtained (mean ± standard deviation
SD) on the quality parameters of fresh semen for
each boar as well as the overall mean of all
ejaculates evaluated are shown in Table 1. For all
of the analyzed variables, the mean values obtained
showed considerable variation between animals.
The classification of the ejaculates from 9
animals is displayed in Table 2. The data are
subdivided according to the ejaculation time and
the total numbers of ejaculates per group and per
boar are also shown. It was observed that in the
total number of ejaculates evaluated, the majority
of these (60.18%) were classified as G1. G2
accounted for only 15.21% of total ejaculates
evaluated, and G3 comprised 24.61% of the
ejaculates.
The variables of volume, motility and intensity
of motion were different (P<0.05) for the three
evaluated groups. It was observed that the
ejaculates from the G3 presented a higher semen
volume compared with the other groups, but with
respect to the motility and intensity of motion,
Group III presented the lowest values compare
with the Group I. For the other variables of sperm
count and morphology there were no differences
(P>0.05) between the groups (Table 3).
With regards to age, the boars classified in
Category I (C1) had a mean age of 11.92±2.42
months, and C2 had an age of 20.49±2.21 months.
It was also observed that the average seminal
volumes and sperm motility for animals over 15
months of age (C2) was significantly higher
(P<0.05) than for animals below this age (C1). On
the other hand, the animals under 15 months of age
presented superior values for sperm count and
morphology variables (P<0.05) when compared
with animals above this age. There was no
difference (P>0.05) in the sperm intensity of
motion between the evaluated categories (Table 4).
A positive correlation was obtained between
the duration of ejaculation and age (r = 0.23;
P<0.01), seminal volume (r = 0.56; P<0.01) and
sperm count (r = 0.121; P=0.01). With regards to
sperm motility and intensity of motion, the
correlation with the ejaculate time was negative (r
= -0.163; P=0.001) and (r = -0.152; P=0.001),
respectively. Conversely, the sperm morphology
was not significantly correlated with ejaculation
time (r = 0.090; P=0.057) (Table 5). For the
variables of sperm count, motility and intensity of
motion, the correlation with ejaculation time was
low.
In this study, all of the mean values obtained
for each analyzed variable in the 9 animals were
within the standards recommended for swine
(Fonseca et al., 1992; Corrêa et al., 2001). The
range of data obtained between the animals is a
common feature found in the semen of boars and a
characteristic also demonstrated in other studies
(Thiengtham, 1992). According to Petrunkina et al.
(2005) there are higher spermatic variations
between ejaculates of the same animal, which
implies that a greater number of ejaculates should
always be used for a reliable evaluation of the data.
Additionally, the fertility and sperm quality of the
same boar can change over time (Bernardi, 2008).
The higher seminal volume ejaculated by
animals of G3 in comparison with the other groups
can be explained by the fact that these animals
spend more time on the dummy, and,
consequently, have a higher probability of
ejaculating a greater volume of semen.
As well as for the ejaculation time, the fact
that animals of C1 (age less than 15 months)
present a lower ejaculate volume is due to the fact
that these animals are still in the pre-pubertal phase
and do not yet have a defined or relatively constant
ejaculate volume. Therefore, this fact is observed
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through the occurrence of longer ejaculations with
a small semen volume, or the complete opposite.
Conversely, C2 animals have already reached
complete sexual maturity and semen volumes have
evolved in comparison with the animals that still
were in the pre-pubertal phase. These results are
consistent with those seen by Jankeviciute and
Zilinskas (2002), who reported an increase in the
seminal volume ejaculate with the advancing of
age.
Table 1: Data (mean ± SD) of fresh semen quality parameters for each boar evaluated and the overall mean, standard
deviation, minimum and maximum value and variation coefficient obtained of the all animalsa
Boar
Nb
Duration of
ejaculation
(seconds)
Seminal
volume
(mL)
Sperm
count
(x109 sperm)
Sperm
motility
(%)
Sperm
intensity of
motion (1-5)
Sperm
morphology
(%)
1
62
519.61 ± 298.98
305.40 ± 98.01
95.14 ± 59.91
77.98 ± 15.77
2.97 ± 0.77
21.42 ± 14.94
2
58
309.95 ± 81.03
198.62 ± 66.54
76.65 ± 58.94
83.19 ± 12.76
3.33 ± 0.71
11.91 ± 8.03
3
50
353.20 ± 151.46
269.50 ± 68.26
93.52 ± 64.85
77.90 ± 17.00
3.04 ± 0.78
20.08 ± 15.34
4
50
304.46 ± 87.37
244.30 ± 65.35
103. 22 ± 61.05
84.40 ± 7.19
3.36 ± 0.56
8.54 ± 6.45
5
48
313.21 ± 62.35
200.42 ± 47.99
72.44 ± 37.75
84.79 ± 6.10
3.21 ± 0.71
25.67 ± 13.03
6
42
360.36 ± 91.00
247.14 ± 61.44
71.04 ± 60.30
81.90 ± 16.53
3.24 ± 0.76
18.12 ± 9.15
7
44
502.05 ± 284.44
286.14 ± 93.39
97.87 ± 67.10
79.77 ± 14.14
3.05 ± 0.68
22.11 ± 16.29
8
43
391.60 ± 149.59
240.81 ± 74.50
88.93 ± 70.79
78.26 ± 14.26
3.09 ± 0.68
22.77 ± 15.56
9
50
337.18 ± 102.62
264.70 ± 79.10
98.11 ± 65.09
84.60 ± 13.40
3.42 ± 0.73
10.50 ± 7.29
Mean ± SD
378.15 ± 186.89
251.29 ± 82.11
88.77 ± 61.56
81.41 ± 13.69
3.19 ± 0.72
17.72 ± 13.51
Minimun
126
40
9.75
10
0
1
Maximun
1860
500
437.90
95
4
60
VC (%)
49.42
32.68
69.35
16.82
22.57
76.24
aValues represent the means for n = 447 ejaculates.
bNumber of ejaculates per boar.
SD: Standard deviation
VC: Variation coefficient
Table 2: Classification of the ejaculates of 9 boars subdivided into three groups according to the total time
duration of the ejaculationa
Boar
Classification of Groupsb
Totalc
Group I (G1)
Group II (G2)
Group III (G3)
1
23
10
29
62
2
43
9
6
58
3
29
9
12
50
4
41
4
5
50
5
39
7
2
48
6
25
6
11
42
7
16
7
21
44
8
23
6
14
43
9
30
10
10
50
Total Groups
269
68
110
447
aValues represent the means for n = 447 ejaculates.
bGroup I (G1) = ejaculation time less than 360 seconds; Group II (G2) = ejaculation time between 360 and 420 seconds;
Group III (G3) = ejaculation time over 420 seconds.
cTotal number of ejaculates per boar.
In this study, the seminal volume average
obtained in across 447 samples from 9 animals was
in the physiological range, with an average that
was lower than those found by other groups.
Henao-Restrepo et al. (2004) worked with 244
ejaculates from 10 boars aged between one and
two years and Alonso et al. (2011) worked with
animals between 15 and 18 months old. However,
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the seminal volume obtained was greater than the
values found by Poto et al. (2000) working with five Chato Murciano boars aged between 10
months and 12 years.
Table 3: Data (mean ± SD) for the sperm quality variables of the ejaculates collected from 9 boars divided into three
groups according to ejaculation timea
Sperm quality
parameters
Classification of Groupsb
P value
Group I (G1)
Group II (G2)
Group III (G3)
Semen volume (mL)
217.81 ± 67.38 c
268.16 ± 51.16 b
322.73 ± 81.98 a
<0.01c
Sperm count (x109 sperm)
91.38 ± 67.03
85.65 ± 73.18
84.31 ± 33.52
0.167d
Sperm motility (%)
82.57 ± 12.95 a
82.35 ± 6.94 ab
78.00 ± 17.60 b
0.003c
Sperm intensity of motion (1-5)
3.26 ± 0.72 a
3.21 ± 0.51 ab
2.99 ± 0.82 b
0.001c
Sperm morphology (%)
17.44 ± 13.96
19.44 ± 13.09
17.33 ± 12.64
0.295d
aValues represent the means for n = 447 ejaculates.
bGroup I (G1) = ejaculation time less than 360 seconds; Group II (G2) = ejaculation time between 360 and 420 seconds; Group
III (G3) = ejaculation time over 420 seconds.
cMeans followed by different letters in the line differ by Mann-Whitney test (P<0.05).
dNot significant with the Kruskal-Wallis test (P>0.05).
Table 4: Data (mean ± SD) for the sperm quality parameters of the ejaculates collected from 9 boars divided into two
categories according to agea
Sperm quality
Parameters
Classification of Categoryb
Mean
P value
Category I (C1)
Category II (C2)
Semen volume (mL)
210.66 ± 57.95 b
275.52 ± 84.87 a
251.29 ± 82.11
<0.01c
Sperm count (x109 sperm)
110.19 ± 82.38 a
75.99 ± 39.76 b
88.77 ± 61.56
<0.01c
Sperm motility (%)
79.82 ± 15.41 b
82.36 ± 12.49 a
81.41 ± 13.69
0.001c
Sperm intensity of motion (1-5)
3.19 ± 0.72
3.19 ± 0.73
3.19 ± 0.72
0.956d
Sperm morphology (%)
21.04 ± 16.36 a
15.74 ± 11.04 b
17.72 ± 13.51
0.001c
aValues represent the means for n = 447 ejaculates.
bCategory I (C1) = animals under 15 months old and Category II (C2) = animals above 15 months old.
cMeans followed by different letters in the line differ by Mann-Whitney test (P<0.05).
dNot significant for the Kruskal-Wallis test (P>0.05).
Table 5: Spearman’s rank correlation coefficients (r) between the duration of ejaculation and sperm quality
parameters of the 9 high performance boarsa
Variable
compared
Age
Seminal
volume
Sperm
count
Sperm
motility
Sperm intensity
of motion
Sperm
morphology
Duration of
ejaculation
r = 0.23b
P<0.01
r = 0.56b
P<0.01
r = 0.121c
P=0.01
r = -0.163b
P=0.001
r = -0.152b
P=0.001
r = 0.090NS
P=0.057
aValues represent the means for n = 447 ejaculates.
bSpearman’s correlation is significant to the level P=0.01.
cSpearman’s correlation is significant to the level P=0.05.
NS: Non-significant
According to Corrêa et al. (2001), the
normal volume of ejaculate in boars can vary from
50 to 500 mL, with an average volume close to
200mL. Therefore, the results from this study are
in the physiological range of swine species, for
animals of G1, G2 and G3, as well as those from
C1 and C2. The volume of the ejaculate is
characteristic of each species and also of each
breed within the same species (Jasko, 1992;
Colenbrander et al., 1993). The volume appears to
have no association with fertility, and affects only
the total number of sperm and doses produced per
ejaculate (Tardif et al., 1999). Although there are
differences between breeds, in this study, the
animals were of the same breed, meaning that the
differences in the seminal volume between the
animals cannot be evaluated for this variable.
The seminal volume presented a high variation
among all evaluated ejaculates as well as among
ejaculates from the same animal, making these
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variations similar to those observed in other studies
(Singleton & Shelby, 1972; Wettermann et al.,
1976; Mazzarri & Fuentes, 1978; Trudeau &
Sanford, 1986; Henao-Restrepo et al., 2004). The
variation in semen volume is mainly due to
individual variation in the size of accessory glands,
and is also related to the amount of sexual
stimulation prior to the collection process
(Coopper, 1980). According to Alonso et al.
(2004), the marked variation in semen volume can
be attributed to factors inherent to the animal or the
environment, such as nutrition, genetics, breed and
management. The seasons also have significant
effects on ejaculate volume, since the production
of semen in the winter is comparatively higher than
in the summer in general (Corrêa et al., 2001). In
this study, the volume variability between boars
can be explained by the individual variation that
exists among animals, by the stimulation time
before the collection process that was different in
each collection for each animal, and also due to the
varying ejaculation time between the animals, in
addition to the factors already discussed above.
The correlation analysis between ejaculation
time, which is an independent variable, and the
seminal volume, a dependent variable, showed that
when there is an increase in the ejaculation time,
the semen volume also tends to increase (r = 0.56).
This correlation can be considered moderate for
this variable, and these data are similar to those
obtained by Kuciel et al. (1983) cited by Levis and
Reicks (2005), who reported a significant
correlation between the duration of ejaculation
with volume of ejaculation (r = 0.58). On the other
hand, these data differ from those of Alonso et al.
(2011) who found an r value of 0.822, which was
higher than the coefficients obtained in this study.
The difference in comparison with the current
study may be explained due to the age of the
animals, as this study evaluated young boars aged
15 to 18 months with little variation in age. Also,
another factor to be taken into consideration is the
different breeds of animals evaluated, which may
result in differences between the sperm
characteristics (Alonso et al., 2004). However, the
ejaculation time was found to have a direct effect
on the volume of ejaculate collected despite this
difference.
In addition to that of seminal volume, the
correlation between ejaculation time and the age of
the animals was moderate. The longer time that the
older animals spend on the dummy is due to the
fact that the seminal volume and spermatic
production increases with age, so more time is
needed for the ejaculation process to reach
completion.
The averages sperm count observed was
88.77±61.56 (x109 sperm per ejaculate), which is
higher than that found by Alonso et al. (2011),
lower than that found by Henao-Restrepo et al.
(2004) and similar to results found by Del Toro
and Diéguez (1997) and Fernández et al. (1996).
The sperm count is indicative of the ability to
produce gametes in the seminiferous tubules and
does not appear to be related to fertility rates, being
associated with seminal dilution rate and
production rate of insemination doses from the
ejaculate (Tardif et al., 1999). This is a highly
variable characteristic between animals and
depends on many factors, including age,
environment, breed and the season (Rodríguez-
Martínez & Wallgren, 2000; Alonso et al., 2011).
In the current study, the average sperm count
obtained is in agreement with the recommended
values for swine (Corrêa et al., 2001).
Although no statistically significant difference
was observed for sperm count between the
different groups (G1, G2 and G3), a numerical
difference was observed. The highest number of
sperm in the ejaculates of G1 can be justified, as
the animals in G2 and G3 had longer ejaculation
times, and also produced higher semen volumes,
leading to a greater degree of sperm
dilution/ejaculate. The consequence of this was a
reduced sperm count in these groups compared
with Group I.
The higher sperm count in the animals of
Category I can be explained by the fact that the
seminal volume of these animals was lower and the
sperm production was either equal or superior to
the C2 animals. Therefore, the higher seminal
volume results in a decreased sperm concentration,
leading to a lower sperm count, wich is associated
with a lower spermatic production in older animals
(C2). These results are consistent with Jankeviciute
INFLUENCE OF EJACULATION TIME ON SPERM QUALITY PARAMETERS …
506
J. Anim. Sci. Adv., 2012, 2(5):499-509
and Zilinskas (2002), who reported a decrease of
this variable with advancing age.
The correlation analysis between ejaculation
time and sperm count showed that when there is an
increase in the ejaculation time, the sperm count
also tends to increase (r = 0.121). This result was
lower that the obtained by Thiengtham (1992),
who observed an r value of 0.38 for the correlation
between ejaculation time and the total number of
sperm in the ejaculate. On the other hand, the
results in the current study were similar to those
obtained by Alonso et al. (2011) who found an r of
0.2148, meaning that both correlations are
considered low. Although this study did not assess
the effect of the seasonality in the seminal
characteristics, according to Kunavongkit and
Proteep (1990) and Sánchez (1991) sperm
production is seasonal, meaning that in the months
of higher temperatures there is a decrease in sperm
production and an adverse effect on the
characteristics of boar semen.
The values obtained for sperm motility are
considered acceptable for fresh semen, especially
for those ejaculates which will later be used for the
preparation of insemination doses, which must
have a minimum of 70% motility (Corrêa et al.,
2001). The results of this study were higher than
those obtained by Alonso et al. (2011) but lower
than in Henao-Restrepo et al. (2004), who also
studied the relationship between ejaculation time
and sperm motility. According to Tardif et al.
(1999) and Silva et al. (2012) motility is one of the
most indicative characteristics of the fertilizing
capacity of boar and bull semen, and there are
negative effects on female fertility when
percentages are low. In the present study, all
animals presented spermatic values of motility
higher than 77%.
The highest values of sperm motility observed
in Groups I and II may have occurred because the
animals of these groups remained on the dummy
for less time (close to 100 seconds less compared
with G3), and the ejaculates obtained were
evaluated more rapidly after the seminal collection
process compared with the other group.
Consequently, it is possible to suggest that
spending less time under the influence of external
factors are favorable to sperm motility.
The correlation analysis between ejaculation
time and sperm motility showed that when there is
an increase in the ejaculation time, the seminal
volume tends to decrease (r = -0.163). These
results are different to those found by Alonso et al.
(2011) who obtained an r of 0.2148 for motility in
relation to ejaculation time. Despite this difference,
both studies showed that the correlation between
these two variables is low.
As well as motility, the intensity of motion
was normal for the boar semen. According to
Corrêa et al. (2001) the minimum amount of
intensity of motion for boar fresh semen that can
be used in AI is 3.0. The higher values of the
intensity of motion obtained for the Group I can be
explained due to the fact that G1 animals remained
on the dummy for a shorter time, and consequently
the sperm also remained in a hostile and harmful
environment for a shorter time. This resulted in the
maintenance of a high quality of sperm.
The correlation analysis between ejaculation
time and intensity of motion also showed similar
results to motility, with a low correlation (r = -
0.152) being obtained between these variables.
Regarding motility and intensity of motion,
correlations exist between these variables and
ejaculation time, but they are not high, which can
be explained because the sperm may have greater
feasibility and be minimally affected by a longer
ejaculation time even if the ejaculation time is
high.
The average results for morphological changes
obtained from the 447 ejaculates are in agreement
with Corrêa et al. (2001) and Fonseca et al. (1992),
who described that the total morphological
abnormalities allowed in boar semen is 20%. The
results are lower than those reported by Henao-
Restrepo et al. (2004), who discovered very high
values of morphological defects in animals housed
in a humid tropical climate. However, the mean
morphological alterations in some individual boars
exceeded 20% of changes. Despite the fact that
these values are higher than those suggested by
some authors, they remain within the standards
established by Barth and Oko (1989) who consider
a viable ejaculate to include up to 30% of changes.
The higher percentage of morphological
changes in C1 animals can be explained by the fact
that the animals are not yet completely mature
OBERLENDER ET AL.
507
J. Anim. Sci. Adv., 2012, 2(5):499-509
sexually (prepubertal). The occurrence of
alternated ejaculations with very different
morphological changes often leading high values
of alterations in the ejaculate is common in this
group (Murgas & Zangeronimo, 2004). Despite
this fact, with the advancing of age and with the
development of the boar (puberty), this
characteristic tends to normalize. Thus, the
percentage of alterations in the ejaculate of a
healthy pubertal animal is within acceptable limits.
The results obtained are similar to those recorded
by Jankeviciute and Zilinskas (2002), who
demonstrated that the spermatic morphology is one
of the variables affected by the age of the animals.
The insignificant correlation analysis between
ejaculation time and morphology is due to the
extreme variability that exists among animals as
well as between the same animal (Petrunkina et al.,
2005). Furthermore, according to Murgas and
Zangeronimo (2004) the spermatic morphology
may be influenced by many factors. However, the
ejaculation time showed no significant effect on
the sperm morphology in this study.
Despite the fact that all of the animals
evaluated did not present with genital diseases, the
evaluation of sperm morphology is a parameter
which allows for the identification of males who
suffer from these pathologies (Henao-Restrepo et
al., 2004). The results generate in this study are not
able to relate morphological defects with semen
fertility. However, according to Rodríguez-
Martínez and Eriksson (2000), the identification of
boars that produce semen of poor quality could be
used to identify possible animal semen donors for
AI programs.
From the results obtained in this study relating
ejaculation time with the parameters of volume,
sperm count, motility, intensity of motion and
morphology of high performance boars, it can be
concluded that the collection time has a major
effect on the variable ejaculate volume. The other
semen quality variables are poorly influenced by
ejaculation time, but there is a set of factors that
can affect these variables. Therefore, even animals
presenting with a good libido and longer
ejaculation times, the semen analysis must be
performed properly to avoid any influence on the
results. Considering the animals destined for AI
programs, these analyses are essential, as all of the
characteristics of semen quality that have been
evaluated are influenced by numerous factors and
not just by the ejaculation time.
The current knowledge of the sexual behavior
influence of boars, such as the ejaculation time,
and the reproductive parameter is small in
comparison with information about factors such as
the spermatic production physiology. Therefore,
more research should be conducted with the use of
a greater number of animals of different breeds,
with the aim of studying factors that may influence
the correlation between sexual behavior and
seminal characteristics.
Acknowledgments
This work was supported in part by FAPEMIG
(the Research Support Foundation of the State of
Minas Gerais), CNPq (the National Council for
Scientific and Technological Development),
CAPES (Coordination of Improvement of Higher
Education Personnel), the Veterinary Medicine and
Animal Science Graduate Programme and the
Graduate Directory of the Federal University of
Lavras, Brazil.
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... Our comparison of the sperm properties of microminipigs with those of common pig breeds identified both similarities and differences. The length of the ejaculation time in microminipigs was comparable to that reported for other pig breeds (31,32). The sperm of microminipigs had a weakly alkaline pH, similar to common pig breeds (33) and other strains of mini pigs (34). ...
... This is likely to be related to the differences in body size between microminipigs and standard breeds; the mean weight of the microminipigs here was 19.7±1.1 kg, which is about one-twentieth of that of standard breeds (39). Per unit weight, ejaculate volume of microminipigs is greater than that of standard breeds (31,32,37,38), although sperm concentration is lower (31,32,37,38); as a result, sperm count per unit body weight was approximately identical in microminipigs to that of standard breeds (31,32,37,40). ...
... This is likely to be related to the differences in body size between microminipigs and standard breeds; the mean weight of the microminipigs here was 19.7±1.1 kg, which is about one-twentieth of that of standard breeds (39). Per unit weight, ejaculate volume of microminipigs is greater than that of standard breeds (31,32,37,38), although sperm concentration is lower (31,32,37,38); as a result, sperm count per unit body weight was approximately identical in microminipigs to that of standard breeds (31,32,37,40). ...
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... The quantity and quality of semen are the primary determinants of boar fertility and represent measurable progress achieved by sires in pig production [7]. AI station economic profitability de- pends on boar capacity and the production of live/motile sperma- tozoa during exploitation [8], and this is limited by dysfunctions impacting upon a later culling [9]. Accordingly, the interest of AI stations is focused on maximizing the longevity of boar reproduc- tion to achieve lower production costs for the AI doses offered for sale. ...
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The aim of this study was a detailed analysis of the boar genotypes used in AI stations with an indication of their production capacity, including age and a precise analysis of their culling time and reason. The study included 334 boars: 81 Polish Large White (PLW), 108 Polish Landrace (PL), 49 Pietrain (P), 56 Duroc × Pietrain (D × P) and 40 Hampshire × Pietrain (H × P). Semen volume, spermatozoa concentration, total number of spermatozoa, number of motile spermatozoa, and number of insemination doses were analyzed. Quadratic regression was used to illustrate the selected sperm parameters at specific ages. Among all the studied boars the lowest motilities of spermatozoa were identified in white breeds PLW and PL, and the difference between motility extremes was 3.53% (P ≤ 0.01). The highest number of insemination doses were produced from D × P crossbreed boars: about 0.7 portions more compared to PL, 1.13 to PLW, 1.18 to H × P and 1.8 to P (all differences P ≤ 0.01). It has been shown in the case of ejaculate volume that for PLW and H × P boars the culling moment was far too early in terms of production capacity and differences were, respectively, 16.35 ml for PLW and 12.61 ml for H × P. Based on the developed regression equations, the earliest maximum number of motile sperm (73.82 × 10⁹) was obtained by H × P crossbreed boars as early as at age 24 months. The highest values for this parameter were achieved, however, by other D × P crossbreed boars: 74.30 × 10⁹ at the later age of 32 months. A consequence of the high number of motile sperm in young H × P boars was that the theoretical maximum value of the number of AI doses was produced as early as the 14th month (25.59 portions). Curves of similar shape were obtained for PL and D × P boars; the difference in maximal values was 0.54 portions in favor of crossbreeds, at a later age of 7 months. It was noted that for PLW and D × P boars the highest number of cullings were due to reduced demand (24.47% and even 31.19%, respectively). Other boars - PL, P and H × P - were most frequently culled because of low semen values. Regardless of the genotype, high survival probabilities (over 0.96) were noted for the age of 12 months. The highest probabilities (still over 0.96) were noted in the longest time period (up to 18 months) for P boars. The results of our study can be used in AI stations as reference points for the exploitation and culling of boars with different genotypes.
... The most important parameter limiting performance and economic profitability of AI stations is the number of insemination doses obtained from ejaculates within a certain time period (Frangež et al., 2005). Assessment of fresh semen is first and foremost the most important step in the audit of insemination doses production process (Oberlender et al., 2012). ...
... The decisive factor is the ejaculatory performance, which is the number of AI doses obtained per ejaculate. It is important that the boar shows the ability to produce ejaculates of rather equal quality throughout its lifetime [3] . Therefore, the aim is to use the boars that demonstrate outstanding ejaculate traits, i.e. a large volume of discharged semen with a high concentration and good motility of sperm [4] . ...
Article
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The quality of semen sires significantly affect the results of artificial insemination of dairy cows. Indicators determining the biological value of sperm are sperm morphology and the state of the hereditary material in chromatin. It is revealed that depending on the degree of fragmentation of DNA in the chromatin of sperm, there are groups with a high degree of fragmentation is over 30%, the average from 10.01% to 30%, moderate 5,01% to 10.0% and the minimum is less than 5.0%.
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Reliable estimates of boar fertility potential from semen evaluation could be a valuable tool for boar selection. The aim of this study was to investigate the morphology and the detailed motility parameters of diluted boar semen and to relate these to their predictive value concerning conception and farrowing rate, litter size and the number of live born piglets. In addition, the optimal time for evaluation of the motility of preserved semen with respect to its predictive effect on fertility was determined. One hundred ejaculates from 38 boars were evaluated morphologically by eosin-nigrosin staining and different motility characteristics were assessed using Computer Assisted Semen Analysis (CASA). The motility was determined at 15, 45 and 120 minutes after incubation at 37 degrees C. The conception rate, farrowing rate, litter size and number of live born piglets were registered from 276 sows inseminated with these ejaculates. Different regression models were used to evaluate the predictive value of the semen characteristics on these fertility parameters, taking into account the effect of herd, parity and weaning to estrus interval. The motility characteristics of the spermatozoa varied significantly during the 15 to 120 minutes of incubation. The longer the incubation time, the more the velocity parameters along the actual cell path decreased, while the parameters of straightforward movement increased. The predictive value of individual semen parameters on conception and farrowing rate was very small. The predictive value of certain associations of different semen parameters, on the other hand, was significant. The percentage of motile spermatozoa had a significant (P
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La precocidad sexual y fertilidad tienen gran impacto en el éxito económico de los rebaños bovinos comerciales, en que las características reproductivas han sido adoptadas como criterios de selección. Sin embargo, la mayoría de estas características dependen de eventos reproductivos de las hembras y, con excepción del perímetro escrotal, pocos estudios abordan las características andrológicas. Las estimaciones de las heredabilidades y correlaciones genéticas de las características testiculares y seminales, además del comportamiento sexual, podrán proveer alternativas para la elaboración de estrategias más adecuadas de selección para fertilidad, en conjunto con las demás características de interés económico.
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The objective of this study was to compare the use and effectiveness of two different techniques for assessing sperm morphology, the conventional wet preparation with a of formaldehyde-citrate solution 2.94% and the smear using Bengal Rose dye. 58 ejaculates from eight high performance boars aged between 8 and 25 months were evaluated. The sperm morphology was evaluated after collection of each ejaculate using two techniques: conventional wet preparation (formol citrate solution 2.94%) observed in phase contrast microscopy (1.000X magnification) and a smear prepared with Bengal Rose dye, examined under an optical microscope (400X magnification). It was observed that the percentage of alterations of head, acrosome, middle piece and total morphological changes did not differ (P > 0.05) between the two methods. A higher number of tail defects (P < 0.05) was obtained by using the smear technique with Bengal Rose dye when compared to the conventional technique, this was probably due to the preparation technique of the smear that could result in a greater chance of tail breaking, leading to the visualization of this anomaly. It is concluded that the use of the Bengal Rose dye is an efficient method for evaluating the sperm morphology of boar semen, and thats pecial care should be taken when preparing the smear to avoid affecting the results, mainly regarding tail alterations.