The Importance of Ejaculate Volume for the Physical Parameters of Ejaculates and Sperm Morphology of Hypor Boars

Abstract

The study aimed at analysing the effects of ejaculate volume on the physical parameters of ejaculates and the sperm morphology of Hypor boars. The analyses involved 114 ejaculates collected from 12 Hypor insemination boars. The ejaculates were classified according to the criterion of ejaculate volume. Three groups were specified: ejaculates with a volume of 251 ml or lower (Group I), ejaculates with a volume of 252-310 ml (Group II), and ejaculates with a volume of 311 ml or higher (Group III). The ejaculates were assessed to identify the basic physical traits and determine the incidence of morphological abnormalities in the spermatozoa, specifying major and minor abnormalities. Furthermore, the morphological structure indices for the spermatozoa were also calculated. Rising ejaculate volume accompanied with a rise in the total number and motility of spermatozoa, and a simultaneous slight fall in sperm concentration in the ejaculates. The ejaculates with the highest volumes turned out to contain more morphologically well-formed spermatozoa. We also determined that rising ejaculate volume is accompanied with increasing sperm dimensions, especially those of the head. The increased parameters were the length and the width of sperm heads, as well as their perimeters and areas. Ejaculate volume has an impact on the shape of Hypor boar spermatozoa. As the ejaculate volume increases, the shape of sperm heads becomes increasingly more oval. Additionally, spermatozoa in ejaculates with greater volumes have larger heads in relation to flagellum length. Özet Çalışmada Hypor erkek domuzların sperm morfolojisi ve ejakülatın fiziksel özellikleri üzerine ejakülat hacminin etkilerini incelemek amaçlandı. Bu amaçla, 12 adet Hypor ırkı suni tohumlama domuzundan alınan 114 ejakülat incelendi. Ejakülatlar hacme göre gruplandırıldı: Numuneler, 251 ml ve altında (Grup 1), 251-310 ml (Grup 2) ve 310 ml ve üstünde (Grup 3) olarak ayrıldı. Sperma, major ve minor morfolojik sperm anomalilerinin sıklığı ve temel fiziksel özellikleri yönünden değerlendirildi. Ayrıca, spermatozoa'nın morfolojik yapısına ait değerler saptandı. Ejakülat hacmi artış ve ejakülasyondaki sperm konsantrasyonunda az miktarda düşüş ile, motilite ve toplam sperm sayısında bir artışla beraber bulundu. En yüksek hacimli ejakülatlarda düzgün yapıda morfolojiye sahip daha fazla sayıda spermatozoa saptandı. Ayrıca, daha yüksek ejakülat hacmiyle birlikte spermatozoonların özellikle baş kısmında olmak üzere ebatlarının büyüdüğü saptandı. Spermatozoonun baş uzunluğu ve genişliği ile çevre uzunluğu ve yüzey alanı büyüdü. Ejakülat hacmi Hypor domuz spermatozoonlarının şekli üzerinde bir etkiye sahipti. Ejakülat hacminin artmasıyla spermatozoa başı daha oval bir şekil aldı. Ek olarak, hacmin artmasıyla ejakülattaki spermatozoa kuyruk uzunluğu ile daha uzun başa sahip olma arasında bir ilişki saptandı.

Full text

Abstract
The study aimed at analysing the eects of ejaculate volume on the physical parameters of ejaculates and the sperm morphology of
Hypor boars. The analyses involved 114 ejaculates collected from 12 Hypor insemination boars. The ejaculates were classified according
to the criterion of ejaculate volume. Three groups were specified: ejaculates with a volume of 251 ml or lower (Group I), ejaculates with
a volume of 252-310 ml (Group II), and ejaculates with a volume of 311 ml or higher (Group III). The ejaculates were assessed to identify
the basic physical traits and determine the incidence of morphological abnormalities in the spermatozoa, specifying major and minor
abnormalities. Furthermore, the morphological structure indices for the spermatozoa were also calculated. Rising ejaculate volume
accompanied with a rise in the total number and motility of spermatozoa, and a simultaneous slight fall in sperm concentration in the
ejaculates. The ejaculates with the highest volumes turned out to contain more morphologically well-formed spermatozoa. We also
determined that rising ejaculate volume is accompanied with increasing sperm dimensions, especially those of the head. The increased
parameters were the length and the width of sperm heads, as well as their perimeters and areas. Ejaculate volume has an impact on
the shape of Hypor boar spermatozoa. As the ejaculate volume increases, the shape of sperm heads becomes increasingly more oval.
Additionally, spermatozoa in ejaculates with greater volumes have larger heads in relation to agellum length.
Keywords: Boar, Ejaculate volume, Morphometric traits, Semen, Spermatozoa
Hypor Domuzlarında Sperm Morfolojisi ve Ejakülatların
Fiziksel Özellikleri Yönünden Ejakülat Hacminin Önemi
Özet
Çalışmada Hypor erkek domuzların sperm morfolojisi ve ejakülatın fiziksel özellikleri üzerine ejakülat hacminin etkilerini incelemek
amaçlandı. Bu amaçla, 12 adet Hypor ırkı suni tohumlama domuzundan alınan 114 ejakülat incelendi. Ejakülatlar hacme göre
gruplandırıldı: Numuneler, 251 ml ve altında (Grup 1), 251-310 ml (Grup 2) ve 310 ml ve üstünde (Grup 3) olarak ayrıldı. Sperma, major ve
minor morfolojik sperm anomalilerinin sıklığı ve temel fiziksel özellikleri yönünden değerlendirildi. Ayrıca, spermatozoa’nın morfolojik
yapısına ait değerler saptandı. Ejakülat hacmi artış ve ejakülasyondaki sperm konsantrasyonunda az miktarda düşüş ile, motilite ve
toplam sperm sayısında bir artışla beraber bulundu. En yüksek hacimli ejakülatlarda düzgün yapıda morfolojiye sahip daha fazla sayıda
spermatozoa saptandı. Ayrıca, daha yüksek ejakülat hacmiyle birlikte spermatozoonların özellikle baş kısmında olmak üzere ebatlarının
büyüdüğü saptandı. Spermatozoonun baş uzunluğu ve genişliği ile çevre uzunluğu ve yüzey alanı büyüdü. Ejakülat hacmi Hypor domuz
spermatozoonlarının şekli üzerinde bir etkiye sahipti. Ejakülat hacminin artmasıyla spermatozoa başı daha oval bir şekil aldı. Ek olarak,
hacmin artmasıyla ejakülattaki spermatozoa kuyruk uzunluğu ile daha uzun başa sahip olma arasında bir ilişki saptandı.
Anahtar sözcükler: Erkek domuz, Ejakülasyon hacmi, Morfolojik özellikler, Sperma, Sperm
The Importance of Ejaculate Volume for the Physical Parameters
of Ejaculates and Sperm Morphology of Hypor Boars
Krzysztof GÓRSKI 1 Stanisław KONDRACKI 1 Anna WYSOKIŃSKA 1 Anna NAZARUK 1
1Siedlce University of Natural Sciences and Humanities, Department of Bioengineering and Animal Husbandry, Faculty
of Natural Sciences, Prusa 14, 08-110 Siedlce - POLAND
INTRODUCTION
The efficacy of insemination largely depends on the
quality of spermatozoa inferred from analyses of sperm
morphology [1,2]. Sperm quality can be also determined
on the basis of an analysis of the damage to the sperm
membrane [3], the state of chromatin structure, the anti-
oxidative potential of the spermatozoa, apoptotic changes
or on the basis of sperm ATP level assays [4,5].
Morphological abnormalities in spermatozoa reduce
male fertility [6]. Particular individuals exhibit dierences
in the quality of spermatozoa they produce. This includes
dierence in the incidence of spermatozoa with morpho-
 İleşim (Correspondence)
 +48 25 6431378; Fax: +48 25 6431272
 gorki@uph.edu.pl
KafKas Universitesi veteriner faKUltesi Dergisi
JoUrnal Home-Page: http://vetdergi.kafkas.edu.tr
online sUbmission: http://vetdergikafkas.org
Research Article
Kafkas Univ Vet Fak Derg
22 (4): 493-501, 2016
DOI: 10.9775/kvfd.2015.14772
Article Code: KVFD-2015-14772 Received: 01.12.2015 Accepted: 30.03.2016 Published Online: 01.04.2016

494
The Importance of Ejaculate ...
logical abnormalities [7]. The shape and dimensions of
spermatozoa are also important. Their dimensions and
shapes determine their motility and capacity to penetrate
the egg [8]. This issue has been dealt with by numerous
researchers who concentrated on the variation in morpho-
metric parameters of spermatozoa, depending on the
physical traits of the ejaculates produced by the sires [9,10].
It is believed that the presence of spermatozoa with head
abnormalities in the semen can be the reason for reduced
embryo quality [11] and miscarriages in the initial period of
pregnancy [12].
The size and shape of the sperm head is a species-related
trait. However, dierences have been identified between
males representing dierent breeds of the same species,
or even between particular individual animals [13]. Some
scientists believe that motor parameters of spermatozoa
depend on their sizes and shapes [14-16]. This has impact on
the competitiveness of spermatozoa in the reproductive
organs of the female. Faster and viable spermatozoa
undergo spontaneous selection following capacitation.
Spermatozoa negotiate a long way in the reproductive
tract of the female, surmounting the immunological barrier,
disadvantageous pH, complex oviduct topography and
the untoward conditions prevalent there [17].
The volume of ejaculated semen varies among animals
depending on nutrition, genetics, breed and management [18].
High-volume ejaculates are considered to be particularly
useful for insemination because they make it possible to
prepare numerous insemination doses containing the
required numbers of spermatozoa. Ejaculate volume is also
important for fertilization efficacy and embryo survival [19].
Semen volume aects the distribution of spermatozoa [20].
Increased ejaculate volume positively inuences the transport
of semen by stimulating the central layer of the uterine
accelerate its contractions and inducing the pituitary body
to release hormones that stimulate contractions of the
smooth muscles of the matrix [19]. Ejaculate volume may
also aect the quality dimensions and shape of sperms,
as well as their motor parameters that determine their
fertilizing ability. Currently, there are studies that indicate a
connection between the sperm morphometric parameters
and concentration in the ejaculates of boars [9].
The present study was aimed at analysing the relation-
ship between ejaculate parameters and sperm morphology
and the volume of ejaculates produced by Hypor boars, on
the basis of physical traits of the ejaculates, morphometric
measurements of the spermatozoa, and an evaluation of
the incidence of morphological sperm abnormalities.
MATERIAL and METHODS
The study concerned 114 ejaculates collected from 12
Hypor boars used at three insemination centres. The boars
(aged 8 to 18 months), were managed in accordance with
the rules of animal welfare [21]. The individual pen area was
10 m2/boar, and the pen had a concrete slatted oor. The
boars were fed according to Swine Nutrition Requirements [22],
with ad libitum access to water. Temperature, relative
air humidity, and atmospheric pressure were measured
during semen collections. Temperature was measured
with a precision of one degree Celsius. Humidity, expressed
as a percentage, was measured with a precision of one
percentage point. Temperature and humidity was recorded
using a thermo-hygrometer TERMIK PLUS (1000209, Termo-
produkt, PL). Atmospheric pressure was measured using an
ADLER barometer (Bar 003, Demus, PL) with a resolution
one hPa. Relative humidity was close to 70%. The air
temperature in the boar pens was 16ºC (average minimum
13ºC and maximum 21ºC). Air pressure inside the buildings
averaged 1005 hPa (min. 987 hPa, max. 1016 hPa). Ejaculates
were collected using the manual method [23] in one-month
intervals over a period of nine months. A total of 114
ejaculates were collected from July 2013 to April 2014.
Each boar provided at least 10 ejaculates for the analysis. The
ejaculates were grouped according by volume as follows:
Group I : ejaculates with a volume below 251 ml - 32
ejaculates,
Group II : ejaculates with a volume between 251 ml and
310 ml - 38 ejaculates,
Group III : ejaculates with a volume above 310 ml - 44
ejaculates.
The following physical parameters were determined
in the freshly collected ejaculates: ejaculate volume (ml),
sperm concentration (x106/ml), sperm motility (%), total
number of spermatozoa (x109), and number of insemination
doses per ejaculate (n). Ejaculate volumes were determined
by weight, without the gelatinous fraction, using electronic
scales. Sperm concentration in the ejaculates was determined
with a photometric method, using a spectrophotometer
(IMV Technologies, France). Sperm motility was evaluated
with a Nikon Eclipse 50i light microscope equipped with
a heated stage. A sample of 5 µl of sperm suspension was
placed on a pre-warmed slide and sealed with a coverslip
at 37ºC. Under 200x magnification, the percentage of
normally motile spermatozoa was determined in the
overall number of sperms present in the field of vision of
the microscope. The total number of motile spermatozoa
and the number of insemination doses per ejaculate were
calculated using SYSTEM SUL (v. 6.35; Gogosystem, Poland)
software package.
Semen samples from the collections were used to
prepare microscopic slides. The slides for morphological
analyses were stained using eosin and gentian violet,
according Kondracki et al.[24]. Microscopic analyses of
the smears were performed under 100x magnification
with immersion lenses, using the Nikon Eclipse 50i light
microscope. The morphology of 500 spermatozoa was
assessed per slide, identifying the number of well-formed
and malformed spermatozoa and differentiating those

495
GÓRSKI, KONDRACKI
WYSOKIŃSKA, NAZARUK
with primary and secondary changes, according to Blom’s
classification [25].
Also, sperm morphometric measurements were carried
out on 15 randomly selected normal spermatozoa in each
slide. The measurements were performed using a suite for
computer image analysis (Screen Measurement v. 4.1),
according to methodology proposed by Kondracki et al.[26].
The following sperm measurements were taken: head
length (µm), head width (µm), head area (µm2), head peri-
meter (µm), agellum length (µm), and total length (µm).
The following morphological indices were calculated on
the basis of the measurements:
head width/head length,
head length/total length,
head length/agellum length,
agellum length/total length,
head perimeter/total length,
head area/total length,
head lengthxwidth/total length.
Experimental data were analysed using a program
STATISTICA® 10 PL (StatSoft, Tulsa, USA) [27]. All results
are expressed as mean (X) ± standard deviation (Sx). The
obtained material was statistically analysed according to
the following mathematical model:
Yij = µ + ai + eij
Where: Yij is the value of the analysed parameter, µ is
the population mean, ai is the eect of ejaculate volume,
eij is the error. The significance of the dierences between
the groups was assessed with the Tukey test at P≤0.05
and P≤0.01.
RESULTS
Table 1 contains data on the physical parameters of
the Hypor boar ejaculates in relation to ejaculate volume.
The data reveal that ejaculate physical parameters are
correlated with ejaculate volume. An increase in ejaculate
volume was accompanied by a decrease in sperm concen-
tration and an increase in sperm motility. With an increase
in volume, the total number of sperm and the number of
insemination doses per ejaculate significantly increased too.
Group I, which comprised the lowest-volume ejaculates,
showed the highest sperm concentrations, which averaged
430.66 x 106/ml and were by more than 18 x 106/ml higher
than in Group II, and by nearly 29 x 106/ml higher than in
Group III, the one with the highest ejaculate volumes. These
dierences were not, however, statistically confirmed.
The data in Table 1 show that spermatozoa in the higher-
volume ejaculates have greater progressive motility. Group
III, comprising ejaculates with the highest volume, was
found to contain spermatozoa with the highest motility.
The percentage of motile spermatozoa in the ejaculates
from this group was more than 3% higher than in Group II
(P≤0.01) and almost 5.5% higher than in Group I (P≤0.01).
The highest sperm counts were found in Group III. The
ejaculates in this group contained over 114 billion spermato-
zoa with progressive motility, over 26 billion more than
those in Group II (P≤0.01) and approximately 40 billion
more than those in Group I, with the lowest volumes
(P≤0.01). The number of spermatozoa in the ejaculate also
determines the number of insemination doses that can be
prepared out of the ejaculate. The most numerous doses
were prepared from the ejaculates in Group III, those with
the highest volumes. Each ejaculate in this group provided
more than 37 insemination doses, approximately 8.4 doses
more than the ejaculates in Group II and over 13 doses more
than the ejaculates in Group I (P≤0.01). Table 2 contains the
results of the analysis of morphological abnormalities in
the spermatozoa.
The mean percentage of normally formed spermatozoa
remained within the range from 94.72% to 96.90%. The
fewest spermatozoa with normal morphology were found
in the ejaculates in Group III. The data presented in Table 2
show Hypor boar semen quality to be very high. The mean
percentage of spermatozoa with major morphological
abnormalities did not exceed 1.71%. The differences
Table 1. Physical traits of ejaculates in relation to ejaculate volume
Tablo 1. Ejakülat hacmne lşkn ejekülatların fzksel özellkler
Specification Groups & Ejaculate Volume (ml)
I (< 251) II (251-310) III (> 310)
Number of ejaculates (n) 32 38 44
Ejaculate volume (ml) X±Sx 217.19±33.14A284.47±15.54B364.09±46.37C
Spermatozoa concentration (x 106/ml) X±Sx 430.66±131.65 412.50±129.98 401.86±103.20
Percentage of spermatozoa with progressive motility (%) X±Sx 73.44±4.82a75.79±5.00b78.86±3.21c
Total number of spermatozoa (x 109) X±Sx 75.21±38.57a88.39±25.15b114.58±18.54c
Number of insemination doses per ejaculate (n) X±Sx 24.22±8.49A29.37±8.78B37.75±8.00C
a,b Dierences between average values, represented by dierent letters in the same row, are important (P≤0.05); A,B Dierences between average values,
represented by dierent letters in the same row, are important (P≤0.01)

496
The Importance of Ejaculate ...
between the groups were slight and statistically un-
confirmed. The highest percentage of spermatozoa with
major abnormalities was found in the semen of the boars
with the highest ejaculate volumes. Among the major
morphological abnormalities, cytoplasmic droplets in the
proximal position in the spermatozoa were most frequent.
The mean percentage of spermatozoa with this defect was
low and did not exceed 0.5% (Fig. 1). The highest numbers
of sperm with minor morphological abnormalities were
found in the semen of Group III (3.60%). The dierences
between the groups were, however, low and statistically
non-significant.
The data in Table 2 suggest that the volume of ejaculates
collected from Hypor boars insignificantly affected the
frequency of morphological abnormalities in the spermato-
Fig 1. Frequency of occurrence of chosen anomaly
of morphological spermatozoa depending on the
ejaculate volume
Şekl 1. Ejakülat hacmne lşkn seçlmş morfolojk
sperm anomallernn görülme sıklığı
Table 2. Frequency of spermatozoa with morphological changes in relation to ejaculate volume
Tablo 2. Ejakülat hacmne lşkn morfolojk değşklklere sahp spermatozoa sıklığı
Specification Groups & Ejaculate Volume (ml)
I (< 251) II (251-310) III (> 310)
Number of ejaculates (n) 32 38 44
Ejaculate volume (ml) X±Sx 217.19±33.14A284.47±15.54B364.09±46.37C
Percentage of normal spermatozoa (%) X±Sx 96.08±3.20B96.90±2.63B94.72±3.72A
Spermatozoa with major abnormalities (%) X±Sx 1.09±1.08 0.91±1.80 1.71±2.05
Spermatozoa with minor abnormalities (%) X±Sx 2.88±2.69 2.18±1.81 3.60±2.93
A,B Dierences between average values, represented by dierent letters in the same row, are important (P≤0.01)
Table 3. Morphometric traits of spermatozoa with regard to ejaculate volume
Tablo 3. Ejakülat hacmne lşkn morfometrk spermatozoa özellkler
Specification Groups & Ejaculate Volume (ml)
I (< 251) II (251-310) III (> 310)
Number of ejaculates (n) 32 38 44
Ejaculate volume (ml) X±Sx 217.19±33.14A284.47±15.54B364.09±46.37C
Head length (µm) X±Sx 8.99±0.55 9.10±0.56 9.19±0.46
Head width (µm) X±Sx 4.73±0.32 4.85±0.30 5.02±0.34
Head perimeter (µm) X±Sx 23.24±1.02 23.59±1.14 23.75±1.32
Head area (µm2) X±Sx 37.88±4.39A39.16±4.57AB 40.53±4.28B
Flagellum length (µm) X±Sx 43.19±1.12a43.84±1.16b43.59±1.37ab
Total length (µm) X±Sx 52.18±1.00A53.02±1.15B52.80±1.62AB
a,b Dierences between average values, represented by dierent letters in the same row, are important (P≤0.05); A,B Dierences between average values,
represented by dierent letters in the same row, are important (P≤0.01)

497
zoa. The results of the morphometric measurements of the
spermatozoa are presented in Table 3.
The data in Table 3 show that the spermatozoa in
the ejaculates with the highest volumes (Group III) have
larger head dimensions than those in the ejaculates
with intermediate and low volume (Group II and I). The
head lengths and widths increase with ejaculate volume.
The spermatozoa in the ejaculates with the highest
volumes (Group III) had 0.17 µm wider heads than those
in the ejaculates in Group II (P≤0.05) and 0.29 µm wider
heads than the spermatozoa in Group I (P≤0.01). The
spermatozoa in the ejaculates of the highest volumes were
also characterized by the largest head areas. The head
area exhibits a clear rising trend in line with the increase in
ejaculate volume (P≤0.01).
Sperm agella in the ejaculates in Group II were on
average 0.65 µm longer than those in in Group I (P≤0.05),
and 0.25µm longer compared to Group III. The spermatozoa
total length was also the greatest in the ejaculates in Group
II, principally due to the longer agella. Table 4 contains
data on the structural indices defining the sperm shape.
The data in Table 4 suggest that the eect of ejaculate
volume on the shape of Hypor boar spermatozoa is non-
significant. Most of the structural sperm morphology
indices assumed similar values in all groups, and the
observed dierences largely remained within the range of
statistical error. It was recorded that the spermatozoa in the
ejaculates with the lowest volume (Group I) had the most
elongated heads, and as the ejaculate volume grew, the
shape of the sperm heads turned increasingly more oval.
This has been confirmed in the head width/head length
index, the highest in the ejaculates in Group III - 1.90 times
higher than in Group I (P≤0.01). The data in Table 4 also
show that as the ejaculate volume rises, the proportions
between the spermatozoa head and the agellum change
as well. With an increase in ejaculate volume, the head
area/total length and head length x width/total length
ratios also increased. Both indices were higher in Group III,
compared to those in Groups II and I (P≤0.05). This suggests
that spermatozoa in ejaculates with higher volumes have
larger heads in relation to the agellum length.
DISCUSSION
The ejaculate volume has a physiological basis and is
associated with the secretory function of the accessory
sexual glands, which produce seminal plasma forming
environment for development, and existence of sperm.
Functionality of the accessory sexual glands depends on
many factors including genetic and non-genetic factors.
Important for the physiology of plasma secretion of semen
components is sexual development of pig males. The
sexual development of pig males is not over at 8-9 months
of age, when boars start to be used for insemination, but
proceeds until a much more advanced age. Some authors
have reported that boar ejaculate volume and sperm
count of the boars grows until the age of around 27-28
months [28,29]. The further development of sexual glands in
sexually mature and active breeding boars is confirmed
by testicular morphology analysis. It was shown that
boar testes increase in size until the age of 20 months [30].
Oestrogens play a crucial role in the control of testicular
development and functionality [31,32]. Dynamically rising
weight of testes during pubescence as well as the number
of reproductive and somatic cells within the parenchyma
of testes may be determined by oestrogen levels.
An essential parameter in the qualitative assessment
of boar semen is the percentage of sperm with superior
motility. The reason is that motility is a symptom of viability
and indirectly reveals the fertilization capability of sperma-
tozoa. Acceptable, fertilisation-capable boar semen should
contain at least 70% of spermatozoa with progressive
rectilinear motion [33]. The data of the present study showed
GÓRSKI, KONDRACKI
WYSOKIŃSKA, NAZARUK
Table 4. Morphometric indices of spermatozoa in relation to ejaculate volume
Tablo 4. Ejakülat hacmne lşkn morfometrk spermatozoa endeksler
Specification Groups & Ejaculate Volume (ml)
I (< 251) II (251-310) III (> 310)
Number of ejaculates (n) 32 38 44
Ejaculate volume (ml) X±Sx 217.19±33.14A284.47±15.54B364.09±46.37C
Head width/head length X±Sx 52.71±3.08A53.42±2.55AB 54.61±2.88B
Head length/total length X±Sx 17.23±1.09 17.15±0.96 17.40±0.66
Head length/agellum length X±Sx 20.84±1.59 20.76±1.40 21.09±0.99
Head area/total length X±Sx 82.76±1.09 82.69±1.31 82.54±0.79
Head length x width/total length X±Sx 44.54±2.09 44.48±1.94 44.96±1.69
Perimeter of the head/total length X±Sx 72.61±8.50a73.79±7.94ab 76.66±6.82b
Flagellum length/total length X±Sx 81.79±9.54a83.46±8.94a87.37±7.88b
a,b Dierences between average values, represented by dierent letters in the same row, are important (P≤0.05); A,B Dierences between average values,
represented by dierent letters in the same row, are important (P≤0.01)

498
The Importance of Ejaculate ...
the spermatozoa in all the analysed groups having a good
motility, much above the values reported by Shipley [34].
It was essential to identify the positive eect of ejaculate
volume on sperm motility. Raising ejaculate volume was
accompanied with a significant increase in sperm motility.
Numerous factors affecting sperm motility have been
reported. Some authors have reported the negative impact
of morphological defects on sperm motility [35], while
others have pointed out the considerable impact of the
hyperosmotic environment of spermatozoa on their
motility [36]. Frequent causes of reduced sperm motility
include spermatogenetic disorders, anomalies in the
functioning of the epididymal epithelium and debilitated
functioning of the additional sexual glands [7]. The correlation
between sperm motility and the physical parameters of the
ejaculate has not been clearly confirmed yet. Publications
on the subject provide inconclusive observations. The
study of Pietrain boars by Kondracki et al.[9] showed the
highest motility in spermatozoa in ejaculates with the
lowest volumes. The progressively motile spermatozoa
identified in the previous study ranged from 75 to 79%, and
was slightly higher in ejaculates with the lowest volumes,
i.e. contrarily to the correlation observed in this study. The
observed changes were, however, non-significant, and
the percentage of spermatozoa with progressive motility
was not too much. Studies of the importance of sperm
concentration have revealed that sperm motility is not
in significant correlation with sperm concentration in
the ejaculate [37,38]. There was no correlation between sperm
motility and the total number of spermatozoa in the
ejaculate has been identified either [17]. The results of the
present study showed that sperm concentration was
slightly higher in ejaculates with lower volumes. This confirms
the existence of an inversely proportional correlation
between ejaculate volume and sperm concentration in
boar ejaculates, as identified in previous studies [24,39].
The total number of sperm increased with ejaculate
volume. The differences were significant and very
pronounced. This is consistent with the expectations,
since the content of motile spermatozoa in the ejaculate
depends on ejaculate volume and sperm concentration.
A directly proportional correlation between the number
of spermatozoa and ejaculate volume has also been
observed in other studies [9].
The results of the present study justify the conclusion
that ejaculate volume affects sperm morphology. The
spermatozoa in ejaculates with dierent volumes dier
in their sizes and shapes, as well as in the incidence of
morphological abnormalities. The spermatozoa in the
ejaculates with the highest volumes (above 310 ml) were
larger in size than those in the ejaculates in Group I - with
the lowest volumes (below 251 ml). Sperm size aects
the motility and fertilization capacity [14,30]. According to
Noorafshan & Karbalay-Doust [16], sperm length is positively
correlated with the speed of sperm motion. Spermatozoa
with longer mid-pieces and agella have stronger tails [40].
The correlation between agellum length, and primarily
mid-piece length, and sperm motility has also been
revealed [14,15,41].
It is probable that, sperm mid-piece length can
be associated with the level of energy originating in
mitochondria [42]. Spermatozoa with longer agella are
more competitive since they might reach the egg faster. The
present authors found that spermatozoa with the longest
flagella were present in ejaculates with intermediate
volumes (251-310 ml). A study by Marmor and Grob-
Menendez [43] revealed that spermatozoa with low motility
could have agella that are shorter by as much as 50%. The
results of the above study were confirmed by Noorafshan
and Karbalay-Dust [16]. The data presented in this work
also validate this correlation, because the lower agellum
length in ejaculates containing spermatozoa with low
motility was statistically confirmed. The interrelation between
agellum length and ejaculate parameters has already
been identified in several studies [44,45]. It has been revealed
that ejaculates with a high sperm concentration contain
spermatozoa with shorter agella [37,46]. However, no clear-
cut correlation was identified between agellum length
and the total number of spermatozoa in the ejaculate [17].
The rising ejaculate volume was accompanied with
increasing sperm head dimensions, including the length,
width, perimeter and area (Table 3). The sperm head
contains the cellular nucleus, which is the primary carrier
of genetic information transferred during fertilization.
The variation in the dimensions of sperm heads can stem
from dierences in chromatin structure [47]. Some reports
informed that even slight modifications in the sperm
head shape can be associated with changes in chromatin
structure in the cellular nucleus [48], leading to reduced
fertility [49]. A correlation has been found between sperm
head dimensions and male fertility. It was observed that
the spermatozoa of males with higher fertility had narrower
and shorter heads [50,51]. The studies by Villalobos et al.[52]
demonstrated a positive correlation between fertility and
spermatozoa head morphometry in swine. It was concluded
that males with high fertility showed the values of 8.9 µm
in length and 4.5 µm in width. The data of the present
work revealed that the spermatozoa in the ejaculates
with the lowest volumes had the lowest head dimensions.
Their heads were shorter and narrower than the heads of
spermatozoa in the ejaculates with higher volumes. The
association of sperm head dimensions with the physical
parameters of ejaculates has also been identified in other
studies [9]. Sperm head dimensions have been observed to
be dependent on the sperm concentration in bull [24] and
boar ejaculates [37,38].
The head shape can be significant in the context of
sperm motility. Spermatozoa with an elongated head
shape move faster than those with rounded heads [53]. The
current data showed that the spermatozoa in the ejaculates

499
with the lowest volumes (Group I) had the most elongated
heads, and as the ejaculate volume increases, the shape
of the sperm heads turned increasingly more oval (Table
4). Helfenstein et al.[54] have reported the existence of a
correlation between the length of the head and agellum
and the speed of sperm motion. Spermatozoa with a
lower ratio of head length to tail length move faster.
Considering the results of the experiment, this refers to
the spermatozoa from the ejaculates classified in Group II
in terms of the volume.
Sperm head dimensions can be aected by the manner
of storage and preservation of semen [55,56]. A study by
Hidalgo et al.[56] revealed that buck sperm heads in refri-
gerated were smaller than those in fresh semen. This was
explained with the damage to or loss of the acrosome, or a
possible change in sperm chromatin structure as a result
of refrigeration. The detection of abnormalities in sperm
heads makes it possible to recognize fertile animals and
those with reduced fertility [57]. Morphometric analyses of
ram spermatozoa have revealed that sires with reduced
fertility have larger sperm heads than fertile males [58].
The reason for the increase in head size can be disordered
spermatogenesis, or changes in chromatin structure during
the maturation and transport of spermatozoa. Sperm head
defects often cause deterioration in the quality of embryos
and lead to miscarriages in the first period of pregnancy [12,59].
The data presented in this work indicate a moderate
correlation between the incidences of sperm morphological
abnormalities and ejaculate volume. However, ejaculates
with the highest volumes had the lowest proportions of
spermatozoa with correct morphology. The presence of
morphologically abnormal spermatozoa reduces male
fertility and was an index of a reduced performance of the
seminiferous epithelium. The incidence of morphological
abnormalities in spermatozoa can result from the inuence
of seasonal factors [60], genetic conditions [12,61], and individual
predispositions [62]. The incidences of morphologically ab-
normal spermatozoa also depend on feeding factors [63].
Large differences in the frequency of morphological
abnormalities in spermatozoa have also been identified
in relation to the age of sires [28,64-66].
Boars with normal fertility always have a certain
percentage of morphologically abnormal spermatozoa [63].
A maximum of 15% spermatozoa with major and 10-15%
with minor abnormalities is acceptable. The presence of
spermatozoa with major abnormalities that have appeared
during spermatogenesis is particularly disadvantageous. A
high percentage of spermatozoa with major modifications,
especially acrosome defects, substantially reduces the
chances for insemination. The data presented in this
study showed that the samples of spermatozoa with
major abnormalities was low and did not exceed 1.71%
in any of the groups. Among the major morphological
abnormalities, the proximal cytoplasmic droplet in the
spermatozoa was the most frequent defect. Such defects
result from anomalies in sperm maturation. The reason
for the appearance of the abnormalities can be a short
a time of sperm maturation in the epididymal duct [67].
It should be noted that the incidence of the tail defects
could be a consequence of an osmotic dierence between
the spermatozoa and the solution in which the sample
is immersed [68]. According to Martin-Rillo et al.[69], a
maximum of 20% spermatozoa with a proximal droplet is
acceptable in collected semen. Any amount in excess of this
level leads to a considerable reduction of male fertility [70].
Ejaculate parameters depend on the volume of
produced ejaculates. The rise in ejaculate volume was
accompanied with an increase in the total number and
motility spermatozoa, as well as with a concomitant slight
fall in sperm concentration. Ejaculates with the highest
volume were highly usable for preparation of more
insemination doses. Ejaculates with the highest volumes had
a larger proportion of spermatozoa with normal morpho-
logy. However, ejaculate volume does not substantially
aect the frequency of morphological sperm abnormalities
in Hypor boar ejaculates. Ejaculate volume influences
morphometric parameters of Hypor boar spermatozoa. The
rise in ejaculate volume is accompanied with an increase
in sperm dimensions, especially with regard to the sperm
head. The increased parameters were the length and the
width of sperm heads as well as their perimeters and areas.
Ejaculate volume had an impact on the shape of Hypor boar
spermatozoa. As the ejaculate volume increases, the shape
of the sperm heads changes from elongated to increasingly
more oval. Spermatozoa in ejaculates with higher volume
had a larger heads in relation to the flagellum length.
When using Hypor boars for insemination purposes, it is
preferred to choose sires with a high ejaculatory efficacy
and producing ejaculates of high volume. Such ejaculates
allow not only for generating more insemination doses,
but also doses including spermatozoa of higher mobility
and quality.
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GÓRSKI, KONDRACKI
WYSOKIŃSKA, NAZARUK