ABSTRACT
The effect of ejaculation frequency on semen characteristics and composition of seminal plasma of Dutch-belted (DB) and New Zealand White (NZW) rabbits was studied. 36 matured rabbits-18 of each breed were used. The semen characteristics and seminal plasma components of the DB and NZW breeds of rabbits were investigated following two frequencies of ejaculation also determined were the relationship between the semen characteristics and seminal plasma components and the effect of ejaculation frequency on libido. The study involved two treatments. Each treatment was subdivided into two groups of 9 rabbits each. These two groups were further subdivided into 3 replicates of 3 rabbits each. Significant differences (p<0.05) were observed in sperm concentration NZW (132.39) and DB (103.77), total sperm NZW (90.03 and DB (51.89); total viable sperm cell NZW (116.68) and DB (84.57); and total abnormality NZW (1.38) and DB (2.22). Significant differences (p<0.05) were also observed between collection rhythms (EF1 and EF2).Progressive motility EF1(83.39) and EF2(71.69);live sperm proportion EF1 (89.04) and EF(80.59); sperm concentration EF1(127.93) and EF2(108.24); total sperm EF1(76.76) and EF2(62.78); and total viable sperm cell EF1(113.91) and EF2(87.23). Interaction between breed and ejaculation frequencies of the semen characteristics indicated significant differences (p<0.05).Breed effect on seminal plasma composition indicated significant difference (p<0.05) in fructose, Glutamic acid and zinc. The effect of ejaculation frequency on seminal plasma components indicated significant difference (p<0.05) in Glutamic acid and zinc in EF1 and EF2. The interaction of breed and ejaculation frequency on the seminal plasma components studied indicated significant differences (p<0.05). A positive relationship was found between breeds at single ejaculation (EF1) between zinc and reaction time (r=0.623); progressive motility gave a positive relationship with Glutamic acid(r=0.632);Within the NZW breed at single ejaculation, a significant difference (p<0.05) was observed between Glutamic acid and reaction time giving a high negative correlation(r=-0.826);total sperm gave a positive relationship with sodium (r=0.811); total variable sperm gave a positive relationship with sodium (r=0.737); normal sperm gave positive relationship with sodium (r=0.795). These results suggest that the New Zealand White breed of rabbit is superior in semen quality characteristics as well as libido to the Dutch-belted breed as observed in the two frequencies of ejaculation studied.
TABLE OF CONTENTS
Title page i
Declaration ii
Dedication iii
Certification iv
Acknowledgments v
Table
of Contents vi
List of Tables xi
List of Plates xii
Abstract xiii
CHAPTER
1: INTRODUCTION
1
1.1 Background
of Study 1
1.2 Statement of Problem 4
1.3 Objectives of the Study 5
1.4 Justification 5
CHAPTER
2: LITERATURE REVIEW 6
2.1
History of Rabbits 6
2.2 Domestication
of Rabbits 7
2.3 Rabbit
Production 10
2.3.1 Breeding
stock 10
2.3.2 Housing 10
2.3.3 Feeding
11
2.4 Rabbit Health and Management 13
2.5 The Value of Rabbit Meat 15
2.6 Rabbit Reproduction 16
2.6.1 Reproductive Anatomy 16
2.6.2 Spermatogenesis 18
2.6.3 Sperm Production 20
2.7 Libido 23
2.8 Artificial Insemination 24
2.9 Semen Characteristics 25
2.9.1 Semen 25
2.9.2 Seminal Plasma 26
2.10 Factors Influencing Semen Production 31
2.10.1 Individual and Genetic 31
2.10.2 Frequency of
Collection 31
2.10.3 Lighting 33
2.10.4 Temperature 33
2.10.5 Age 34
2.10.6 Health status 34
2.10.7 Feeding protocols 35
2.10.8 Semen collection 37
2.11 Characteristics of
Spermatozoa 38
2.11.1 Sperm concentration
(Sperm count) 38
2.11.2 Semen volume 39
2.11.3 Semen colour 40
2.11.4 Sperm motility 41
2.11.5 Spermatozoa
morphology 42
2.11.6 Live and dead sperm
proportion 43
2.11.7 Semen pH 43
CHAPTER 3:
MATERIALS AND METHODS 45
3.1 Experimental Site 45
3.2 Experimental Animals and Management 39
3.2.1 Experimental diet 41
3.3 Experimental Treatment and Design 48
3.4 Experimental
Animals and Management 48
3.5 Statistical
Analysis 49
3.6 Experimental Procedures and Data Collection 49
3.6.1 Body weight 49
3.6.2 Reaction time and Libido 50
3.7 Seminal Characteristics 50
3.7.1 Semen volume (ml) and Colour 50
3.7.2 Motility (%) 50
3.7.3 Live sperm proportion (%) 50
3.7.4 Total sperm 51
3.7.5 Abnormal sperm proportion (%) 51
3.7.6 Sperm cell concentration (×106ml) 51
3.8 Seminal Plasma Constituents 52
3.8.1 Fructose 52
3.8.2 Glucose 52
3.8.3 Glutamic acid 53
3.8.4 Sodium 53
3.8.5 Zinc 54
3.8.6 Statistical analysis 54
CHAPTER 4 :
RESULTS AND DISCUSSION
55
4.1
Semen Colour 55
4.2 Effect of Breed on Semen Characteristics of Rabbits 55
4.3 Semen Characteristics 58
4.4 Effect of Ejaculation Frequency on Semen Characteristics 60
4.5 Effect
of Interaction between Breed and Ejaculation
Frequencies of Rabbit Semen Characteristics 65
4.6 Effect of Breed on the Seminal Plasma Components of Rabbits 72
4.7 Seminal Plasma Components 74
4.7.1
Effect of Ejaculation Frequency
on the Seminal Plasma
Components of Rabbits 75
4.7.2
Interaction Effect of Breed and
Ejaculation Frequency on
the
Seminal Plasma Constituents of Rabbits 78
4.10 Correlation
of Semen Quality Parameters and
Seminal Plasma Components of Once
Ejaculated of
NZW and DB Breeds of Rabbits 82
4.11 Correlation 83
4.12
Correlation of Semen
Characteristics Parameters and
Seminal Plasma Components of Twice
Ejaculated NZW
and DB Breeds of Rabbits 84
4.13 Correlation
of Semen Characteristics Parameters and
Seminal Plasma Components of Once
Ejaculated and
Twice Ejaculated New Zealand White Rabbits 86
4.14
Correlation of Semen
Characteristics Parameters and
Seminal Plasma Components of Once and
Twice Ejaculated
Dutch-belted Rabbits 88
CHAPTER 5 :
CONCLUSION AND RECOMMENDATION 90
5.1
Conclusion 90
5.2
Recommendation 93
References 94
LIST OF TABLES
Table 3.1: Partitioning
of rabbits into groups 48
Table 4.1: Effect of Breed on Semen Characteristics 51
Table 4.2: Effect
of Ejaculation Frequency on Semen
Characteristics 64
Table 4.3: Effect of
Interaction of Breed and Ejaculation Frequency
on Semen Characteristics 71
Table 4.4: Effect
of Breed on Seminal Plasma Components 74
Table 4.5: Effect of Ejaculation Frequency on Seminal Plasma
Components 77
Table 4.6: Effect of Interaction of Breed and Ejaculation Frequency on
Seminal Plasma Components 81
Table 4.7:
Correlation of Semen
Characteristics Parameters
and Seminal Plasma
Components of Once Ejaculated
New Zealand White
and Dutch-belted Rabbits 83
Table 4.8: Correlation of Semen Characteristics
Parameters and
Seminal Plasma Components of Twice Ejaculated
New Zealand White and Dutch-belted
Rabbits 85
Table
4.9: Correlation of Semen
Characteristics and
Seminal Plasma Components at Once
Ejaculated
and Twice Ejaculated New Zealand
White Rabbits 87
Table 4.10: Correlation of Semen Characteristics and
Seminal Plasma Components of Once Ejaculated
and Twice Ejaculated Dutch-belted Rabbits 89
LIST
OF PLATES
Plate 1: Artificial vagina 46
Plate 2: Eppendorf tubes 47
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF STUDY
Today, rabbit farming has become a well
received progression in animal farming. This is due to rapid human population
growth and low protein intake which are some of the major problems that
developing countries face (Akpa et al.,
2012). The increasing demand for animal protein coupled with inadequate supply
of animal source of protein from the principal livestock species such as cattle,
sheep, goats, pigs and poultry has made it important that attention be shifted
to other micro-livestock such as rabbit (Biobaku and Dosunmu 2003; Fayeye and
Ayorinde 2003). This is because rabbit production has been perceived to have
the potential of alleviating the problem of inadequate animal protein supply in
developing economies. This according to Ghosh et al. (2008), is attributed largely to the rabbit’s high rate of
reproduction, early maturity, rapid growth rate, efficient food utilization and
meat of high nutritional value. In line with efforts directed towards meeting the
daily needs of the citizens, Foods and Agricultural Organization (1987) states
that rabbits may play a partial role in bridging the animal protein gap.
Research on rabbits in recent years in
Nigeria has been mostly in the effect of diet, or growth performance, meat
chemical composition and quality (Awonorin et
al., 1994). Therefore, in order to improve the reproductive capability of
rabbits in Nigeria, assessment of the semen characteristics of the breeds of
rabbit found here is of paramount importance. Akpa et al., (2012) affirms that the assessment of rabbit semen is an
excellent indication of the reproductive capacity of the animals. It is therefore important to understand and
improve the reproductive performance of rabbits in Nigeria, in order to select
bucks of high fertility and for the purpose of using ejaculate that can be
relied upon to give a high conception rate for aiding artificial insemination
programmes and increased productivity. Hence, the ability for a farmer to
record good success in breeding of farm animals depends greatly on the fertility
status of the animals used. Umesiobi et
al., (2000) opined that parameters for measuring reproductive performance
in male animals include: sperm concentration, sperm motility, live/dead
spermatozoa and proportion of morphologically deformed sperm. Furthermore,
Gbadamosi and Egbunike (1999) stated that reproductive inefficiency is the most
limiting constraint to effective rabbit production in the tropics. Therefore,
to forestall some of these inefficiencies, artificial insemination introduced
over 20 years ago in rabbit farming (Paufler et al., 1979; Battaglini et
al., 1986; Theau-Clement and Roustan, 1992) has proved a beneficial
technique in terms of management, profitability, genetics and health. One of
the most immediate benefits has been the reduction in the number of males. As a
result, males used must be more intensively selected. Breeding males must have
good semen yield both in terms of quality and quantity (Panella and Castellini,
1990; Battaglini, 1992; Castellini and Dal Bosco, 1998).
In order to predict fertility before artificial
insemination, different in vivo tests techniques have been developed and
modified to evaluate spermatozoa quality. It has also enabled breeders to
determine the fertility status of a sperm cell (Paal et al., 2014). These tests include the Computer- assisted semen
analysis (CASA), which provides a repeatable estimate of many spermatozoa
movement and also allows the determination of specific motion characteristics
of a sperm cell. Alvarino, (2000) stated that seminal characteristics are
affected by many factors which include: breed, feeding, health status, rearing
condition, season and collection frequency, etc.
Studies on the effect of collection rhythm
on rabbit semen characteristics have particularly been focused on volume,
concentration, pH, live and motile cells, and kinetic characteristics of
spermatozoa (Carvajal et al., 1993;
Bencheikh et al., 1995; Lopez et al., 1996; Theau-Clement et al., 1999; Nizza et al., 2003). Several authors have studied various semen
collection rhythms that vary from one to four ejaculations per day (Bodnar et al., 1996; Bunaciu et al., 1996; Lopez et al., 1996), weekly schedules varying from once weekly (Bunaciu,
1995; Bunaciu et al., 1996) to daily
collections (Bodnar et al., 1996).
Previous studies have examined how the intensification of collection rates has
increased the quantity of semen per week but inevitably had an adverse effect
on quality. Bencheikh (1995) and Moce et
al., (2000) agree that two ejaculates collected once a week (in a period of
at least 15 minutes), gives good semen production results.
The libido of rabbit studs is also of
interest as it is the physical expression of the physiological state of the
animal as well as the degree of responsiveness of the animal to its
environmental conditions. Morsy (2007) found that the reaction time was longer
in the hot season (74 seconds) than in the cold season (46 seconds). This, he
further reported may be related to the adverse effect of the hot season, which
resulted in low physical performance of bucks under environmental Egyptian
conditions and/or low quality semen occurring during hot conditions. On the
other hand, Zeidan et al., (1997)
reported that the delay in reaction time may be due to a decrease in
testosterone level and minimal spermatogenesis.
As production directly depends on
reproduction, the reproductive performance of rabbits becomes an important
aspect in determining the profitability of commercial rabbit breeding (Apori et al., 2014); therefore, the present
study investigated the effect of ejaculation frequency on the semen
characteristics as well as the seminal plasma components of two breeds of
rabbit bucks.
1.2
STATEMENT OF THE PROBLEM
The difficulties encountered in breeding
rabbits of optimum quality here in the tropics primarily for the purpose of
meat production, spurred on this research. Many rabbit farmers in the tropics
have little or no knowledge about the reproductive physiology of the
Dutch-belted and New Zealand White rabbits since little or no comparisons
between the breeds have been done. No evaluation on the seminal plasma
constitution is available for enlightenment. Apparently, evaluating the effect
of ejaculation frequency on seminal characteristics and composition of seminal
plasma would create the much needed awareness for the production of excellent
breeds of rabbits in the tropics; and eliminate/reduce the negative effects of inappropriate
use of the buck by farmers.
1.3 OBJECTIVES OF THE STUDY
1. To
determine the semen characteristics of the Dutch-belted and New Zealand White
breeds of rabbits taken once a week and twice a week respectively.
2. To
determine the seminal plasma composition of the Dutch-belted and New Zealand
White breeds of rabbit.
3. To
determine the relationship between seminal plasma components and semen characteristics
of rabbits following two frequencies of ejaculation.
4. To
determine the effect of ejaculation frequency on libido in the Dutch-belted and
New Zealand White breeds of rabbit.
1.4 JUSTIFICATION
Among the numerous challenges faced by
animal breeders in this part of the world, that of under-utilization of the
male greatly affects the yield of animals in every farm. This automatically
reduces the quantity of animal protein available to the masses. Therefore, to
curb losses accruing from the continual use of low- performing rabbit bucks in
rabbit farms, the outcome of this study will provide valuable knowledge in
addition to the previous researches done on the performance of rabbit bucks as
regards the semen characteristics as well as seminal plasma composition of two
breeds of rabbit bucks. The result of this study will produce baseline
information to farmers on the appropriate mating frequency to be undertaken for
the breeds of rabbit bucks used for the study thereby, assisting rabbit farmers
in fully harnessing the reproductive potentials of the two breeds of bucks
experimented with.
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