ABSTRACT
The study was conducted (July, 2011 – June, 2012) to determine the influence of age and body condition on semen quality, testicular and body dimensions in Red Sokoto goats of two hair types using 31 Red Sokoto bucks. The ages of the bucks were categorized into four; 9 -12, 13-16, 17-20 and 21-24 months. The hair types were categorized into short-smooth (SS) and long-curly (LC). The body condition was scored and categorized as score 3 and 4. Weight records and linear body measurements were obtained. Testicular length and testicular circumference were measured using flexible tape while testicular width and testicular weight were estimated using the appropriate formulae. The semen trait, sperm morphological defects and semen cation concentrations were evaluated accordingly. The results showed that the mean BW, HG, ST, CW, WH, BD, BL, RW, TL, TC, TW and TWT were 15.02 Kg, 59.9 cm, 54.95 cm, 8.37 cm, 53.41 cm, 32.86 cm, 57.35 cm, 17.03 cm, 12.00 cm, 17.38 cm, 5.53 cm and 203.04 g; while 0.52, 0.64, 0.52, 1.03, 0.61, 94.90, 67.79, 2.62, 5.42 were for DMT, MPD, DH, CBT, ACR, Na, K, Ca and PO4, respectively. Semen volume, sperm motility, semen pH, sperm concentration and live & dead ratio were 0.42 ml, 79.52 %, 8.85, 701.13 x 106/ml and 0.82 %, respectively. Age and BCS significantly (P<0.01) influenced BW, body conformation and testicular traits, but had a variable influence on semen traits. DMT, MPD and CBT were more frequent in younger-matured bucks of between 13 and 20 months of age than bucks of later ages while DH and ACR occurred in the younger (9 – 12 months) and older bucks (21 – 24 months of age). Semen cation concentrations were relatively higher in the older bucks of 21 – 24 months than the younger bucks except for Na+ which was also high in younger bucks of 9 – 16 months. Hair type had influence (P<0.01) on some testicular traits. Long-curly haired bucks had the highest DMT and CBT, while the short-smooth haired bucks had the highest DH. Bucks with lower BCS showed higher DH than bucks with higher body condition. Body measurements correlated positively and significantly with testicular measurements (0.25 – 0.61). Body (0.27 – 0.45) and testicular (0.25 – 0.39) measurements were positively correlated to some semen traits. Relationship between semen cations and sperm morphological traits were generally negative and significant (r = -0.28 to -0.40) except ACR which was positively and significantly correlated with Ca2+ (r = 0.37). Semen volume was positively and significantly correlated with K+ and Ca2+ (P<0.05; r = 0.27 – 0.31). Sperm motility was positively and significantly correlated with Na+ and K+ (P<0.05; r = 0.26 – 0.33). Ca2+ was positively and significantly correlated with testicular measurements (P<0.05; r = 0.34 – 0.39). Bucks with BCS 4 were bigger in size (HG, ST, WH, BL, RW) and weighed more (BW) and had scrotum that were longer (TL), broader (TC), wider (TW) and heavier (TWT); hence produced more semen (SV) with higher concentration of Na than those with BCS 3. Bucks aged 21-24 months with short-smooth hair and higher body condition gave better testicular dimensions and exhibited less occurrence of sperm abnormality than the young, long-curly haired and lower body condition bucks. Therefore, bucks aged 21-24 months with larger body and testicular size can be exploited for optimum breeding performance. When considering hair type as an
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indicator of semen quality, short-smooth haired bucks could be used as selection criteria in Red Sokoto goats.
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TABLE OF CONTENTS
TITLE PAGE………………………………………………………………………………………………. i
DECLARATION…………………………………………………………………………………………. ii
CERTIFICATION……………………………………………………………………………………….. iii
DEDICATION…………………………………………………………………………………………….. iv
ACKNOWLEDGEMENTS …………………………………………………………………………v
ABSTRACT………………………………………………………………………………………………… vi
TABLE OF CONTENTS……………………………………………………………………………… vii
LIST OF TABLES……………………………………………………………………………………….. xi
LIST OF ABBREVIATIONS………………………………………………………………………..xiii
CHAPTER ONE
1.0 INTRODUCTION………………………………………………………………………………..1
1.1 Background Information…………………………………………………………………….. ..1
1.2 Justification of Research…………………………………………………………………….. ..4
1.3 Statement of Research Hypothesis………………………………………………………….5
1.4 Objectives of the Study…………………………………………………………………………5
CHAPTER TWO
2.0 LITERATURE REVIEW………………………………………………………………………6
2.1 Goat Population and Distribution……………………………………………………………6
2.1.1 Red Sokoto Goats………………………………………………………………………………….7
2.2 Qualitative Characteristics……………………………………………………………………..9
2.2.1 Hair type in goats ………………………………………………………………………………….9
2.3 Body Weights in Goats…………………………………………………………………………10
2.4 Body Condition Score (BCS)………………………………………………………………..14
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2.5 Body Linear Measurement (BLM)…………………………………………………………17
2.5.1 Heart girth………………………………………………………………………………………….18
2.5.2 Height at withers……………………………………………………………………………….. 20
2.5.3 Body length………………………………………………………………………………………. 23
2.6 Predicting Body Weight Using Linear Measurements…………………………… 25
2.7 Testicular Biometry in Bucks…………………………………………………………….. 28
2.8 Fixed Factor Effects on Measured Characteristics…………………………………. 31
2.8.1 Effect of age…………………………………………………………………………………….. 31
2.8.2 Effect of sex……………………………………………………………………………………… 33
2.8.3 Effect of breed………………………………………………………………….. 34
2.8.4 Effect of season………………………………………………………………………………… 35
2.9 Factors Affecting Fertility in Bucks……………………………………………………. 35
2.9.1 Male associated factors…………………………………………………………………….. 35
2.9.2 Season…………………………………………………………………………………………….. 37
2.9.3 Nutrition………………………………………………………………………………………….. 37
2.10 Semen Characteristics……………………………………………………………………….. 38
2.10.1 Semen collection frequency………………………………………………………………. 38
2.10.2 Semen evaluation……………………………………………………………………………… 38
2.10.2.1Semen colour…………………………………………………………………………………… 38
2.10.2.2Semen volume…………………………………………………………………………………. 39
2.10.2.3Semen pH………………………………………………………………………………………… 40
2.10.2.4Sperm motility…………………………………………………………………………………. 41
2.10.2.5Sperm concentration…………………………………………………………………………. 41
2.10.2.6Sperm morphology…………………………………………………………………………… 42
2.11 Biochemical Parameters of Semen……………………………………………………… 43
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CHAPTER THREE
3.0 MATERIALS AND METHODS………………………………………………………… 45
3.1 Experimental site………………………………………………………………………………. 45
3.2 Experimental Animals and their Management………………………………………. 45
3.3 Data Collection…………………………………………………………………………………. 46
3.3.1 Body weight measurement…………………………………………………………………. 46
3.3.2 Body linear measurement………………………………………………………………….. 46
3.3.3 Testicular measurement…………………………………………………………………….. 47
3.3.4 Semen collection and evaluation………………………………………………………… 48
3.3.4.1 Semen collection………………………………………………………………………………. 48
3.3.4.2 Semen evaluation………………………………………………………………………………. 48
3.4 Determination of Factors……………………………………………………………………. 50
3.4.1 Age determination……………………………………………………………………………… 50
3.4.2 Hair type……………………………………………………………………………………………51
3.4.3 Body condition score (BCS)…………………………………………………………….. 51
3.5 Statistical Analysis……………………………………………………………………………. 52
CHAPTER FOUR
4.0 RESULTS………………………………………………………………………………………… 54
4.1 Body Conformation, Testicular and Semen Characteristics…………………….. 54
4.2 Sperm Morphological Characteristics and Semen Cation
Concentrations………………………………………………………………………………….. 63
4.3 Correlated Relationships Between Body Conformation, Testicular and
Semen Characteristics in Bucks………………………………………………………….. 69
4.4 Correlated Relationships Between Sperm Morphological
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Characteristics and Semen Cation Concentrations in Bucks…………… ……..79
CHAPTER FIVE
5.0 DISCUSSION………………………………………………………………………………….. 91
5.1 Body Conformation, Testicular and Semen Characteristics……………………. 91
5.2 Sperm Morphological Characteristics and Semen Cation
Concentration…………………………………………………………………………………. 100
5.3 Relationships Between Body Dimensions, Testicular and
Semen Characteristics in the Bucks…………………………………………………… 106
5.4 Relationships Between Sperm Morphological Characteristics and
Semen Cation Concentrations in Bucks……………………………………………… 112
CHAPTER SIX
6.0 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS…………… 118
6.1 Summary…………………………………………………………………………………………118
6.2 Conclusions……………………………………………………………………………………..121
6.3 Recommendations…………………………………………………………………………….122
References………………………………………………………………………………………………….123
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CHAPTER ONE
1.0 INTRODUCTION
1.1 Background Information
Livestock of different species fulfill different functions in the household economy and poor families often keep a diversity of species for this reason (Anderson, 2003). Domestic goats (Capra hircus, L.) are important and adaptable domesticated animals (Abdel-Aziz, 2010). They provide a full range of useful products to humans including meat, milk, skin and hair. They efficiently survive on available shrubs and trees in harsh environment and in low fertility lands where no other crops can be grown in Nigeria. Goat production over the years has been one of the major means of improving the livelihoods of poor livestock keepers, reducing poverty and attaining sustainable agriculture and universal food security (Abdel-Aziz, 2010). The population of goats in Nigeria is estimated at 53.8 million (FAOSTAT, 2011) of which traditionally reared stock contributes 99.97%, while 0.03% of the stock is commercially managed. Based on morphology, the two most important goat breeds traditionally recognized in Nigeria are the Red Sokoto (RS) and the West African Dwarf (WAD) goats (Ebozoje and Ikeobi, 1998).
In order to develop a very good model for the genetic improvement of goats, it is important to measure the traits of interest with some high level of accuracy. Since goats are mostly kept for their meat, the most important trait of interest for genetic improvement is the body weight. Body weight is often the most common and informative measure of animal performance (Adeyinka and Mohammed, 2006).
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It has been found to be very effective in assessing the reproductive efficiency and performance in goats (Bongso et al., 1984) and provide readily obtainable and informative measure for selection, feeding and health care (Thiruvenkandan, 2005). Numerous studies have been carried out on the linear measurements of Nigerian breeds of goats and their relationship with economic characteristics, reproductive performance and possible use for estimating the animals’ live weight (Akpa et al., 2010; Adeyinka and Mohammed, 2006), but very few have explored the use of testicular measurements for the same purpose. Bongso et al. (1984) reported that males with higher values of testicular parameters had higher body weight.
Body size and testicular traits of domestic animals are important parameters in breeding soundness evaluations. The extent of growth in body and testicular sizes determines the production of viable spermatozoa and the ultimate number of progeny. The testicular size has been shown to be a reliable measurement of the reproductive growth status, spermatogenic capacity and seminal characteristics (Keith et al., 2009). Body size, as expressed via body weight and physical linear measurements, is closely associated with testicular mass, a phenomenon which explains why testicular growth occurs in parallel to increase in body size (Ahmad et al., 1996; Mekasha et al., 2007a).
In environment with high ambient temperature and intense solar radiation, characteristics like coat pigment and hair type may play a vital role in adaptation. Importance of hair type had also been stressed for heat absorption and heat loss and thus, for adaptability of animals (Banerji, 1984). Animals with a wooly coat type are less adaptable to hot climates (Peters et al., 1982). Bucks show lower reproductive activity during high ambient temperatures (Roca et al., 1992).
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Sperm morphology is used as one of the most important criteria in the evaluation of semen quality (Bearden and Fuquay, 1997). In artificial insemination, the genetic impact of a superior buck is determined by the number of does inseminated and this is limited by the number of sperm and quality of semen. However, before considering the sequences of events at insemination, an understanding of good quality semen is desirable (Hunter, 1985). The quality of semen in relation to fertility is determined by the volume of ejaculate, sperm concentration and motility, percent of live sperm and the sperm morphology. The knowledge on correlations of male reproductive traits among themselves and with other variables such as age, weight, and body condition and testis size might have important bearings to indicate the real producing ability of a male for sperm output and quality of semen. Poor sperm morphology is an indicator of decreased fertility in many species, including goats (Chandler et al., 1988). An accurate morphological examination of spermatozoa thus enables the elimination of males with potentially low fertility prior to the preservation of their semen (Rodriguez-Martinez and Barth, 2007).
Mineral concentrations in the seminal plasma provide the congenial milieu for the survival of sperms (Kalita et al., 2006). The concentrations of different elements in seminal plasma also reflect the quality of semen and physiological status of reproductive accessory gland (Kalita et al., 2006). It is known that the seminal plasma contains substances that support the sperm cells. Sodium (Na+) and Potassium (K+) cations in the seminal plasma establish the osmotic balance (Zamiri and Khodaei, 2005), also calcium (Ca2+) is needed for stimulation of steriodogenesis in leydig cells of the testis (Henricks, 1991). A large number of reports on the biochemical composition of cattle semen have been published (Rattan, 1990).
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But there is scarcity of parallel information about the semen of the Red Sokoto bucks maintained in the northern part of Nigeria. Abnormal levels of Ca, Na, K, Zn, and Cu in seminal plasma have been reported to be correlated with infertility in humans (Nasrin, 2003). Calcium is the trigger for the acrosome reaction in mammalian spermatozoa and there is substantial evidence that Ca is differentially involved in sperm motility, depending on the stage of sperm maturation. However, Magnus et al. (1990) reported no association between ionized calcium concentrations and the proportion of spermatozoa displaying progressive movement. In ram, increasing potassium level is negatively correlated to progressive motility, while the reverse is true for sodium and chloride (Abdel-Rahman et al., 2000).
1.2 Justification of Research
By using bucks with a high concentration of spermatozoa in their testes, more does per buck can be successfully bred (Gherardi et al., 1980). However, evidence of a relationship between testicular size and sperm characteristics is inconclusive. While some researchers suggested that testicular size provided a good index of testicular sperm output in rams (Lino, 1972), others reported that biweekly scrotal measurements were poorly correlated with semen quality in adult rams (Langford et al., 1998). Fernandez et al. (1990) did not record a relationship between testicular size and sperm production. These conflicting data justify the need for further studies on the relationship between testicular measurements and semen characteristics in bucks. Very few researchers have explored the use of testicular measurements in conjunction with linear measurements for the possible estimation of animals’ live weight in Nigerian breeds such as Red Sokoto Goat. Comparative information on this aspect is scarce regarding indigenous bucks in general.
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Establishment of measureable criteria for judging breeding soundness and guiding selection of male goats for breeding, have not been fully documented. Breeding soundness examination (BSE) is a valuable, practical tool for the selection of the best breeding bucks in a flock. For Red Sokoto bucks, information is almost non-existent with regards to the relationships between body conformation, testicular traits and reproductive performance under tropical conditions. Paucity of information or lack of systematic research regarding when bucks should be used for breeding or an age range within which semen production attributes are optimal, make it difficult to determine the optimum age range for efficient breeding and semen collection.
1.3 Statement of Research Hypothesis
The study was designed to evaluate the following hypothesis:
Ho: Reproductive performance of Red Sokoto buck is not influenced by body conformation, testicular traits, age, body condition and hair type.
Ha: Reproductive performance of Red Sokoto buck is influenced by body conformation, testicular traits, age, body condition and hair type.
1.4 Objectives of the Study
The objectives of this research were to: Determine the effect of hair type, body condition and age on the measured reproductive traits in Red Sokoto bucks Investigate the semen quality of the bucks. Determine the relationship between body and testicular traits; semen traits, age, hair type and body condition in a bid to predict their association with fertility.
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