ABSTRACT
This study was conducted to investigate the effect of 45 and 60 minutes of exposure of crossbred (LW x Local) and exotic (LW) boars to tropical solar radiation on their body temperature pattern, libido, semen quality and haematological profile. 12 LW x Local and 12 LW boars of 10 months old were used for the experiment. The experiment was carried out in the Piggery Unit of the Department of Animal Science Farm, University of Nigeria, Nsukka for a period of eight weeks (4 weeks for the exposure and, another 4 weeks for the boars to recover). The results showed that, in the exposure period, the rectal temperature of the boars exposed to solar radiation significantly (P<0.05) increased from 36.80 ± 0.360C to 41.88 ± 0.470C in LW x Local and 37.23 ± 0.360C to 42.04 ± 0.240C in LW boars and these changes varied significantly (P<0.05) between the durations of the exposure. The hyperthermic state of the exposed boars adversely affected the libido, semen quality and haematological characteristics. Specifically, the values for sperm progressive motility, sperm concentrations, sperm abnormalities, reaction time, and ejaculation time were significantly (P<0.05) affected between genotypes and between durations of exposure to thermal treatments. The interactions effects of genotype and duration of exposure (G x D) were highly significant (P<0.01) in all these parameters. Total volume of ejaculate was significantly (P<0.01) higher in LW boars than LW x Local, while volume of gel-fraction, strained ejaculate and semen pH were not significantly (P>0.05) different between genotypes and between durations of exposure. G x D interaction also had no significant effect on these parameters. Total ejaculate volume was not significantly (P<0.05) affected by durations of exposure and G x D interaction. Erythrocyte count, PCV, Hb concentration, MCV, MCH and MCHC were significantly different (P< 0.05) between genotype and between durations of exposure to thermal stress. G x D interaction significantly (P< 0.05) influenced these parameters. In the recovery phase, the two genotypes were reared under average ambient temperature of 26.100C. They returned to their normal body temperature of 37.00 ± 0.190C and 36.97 ±0.200C for LW x Local and LW boars respectively within period of one hour after withdrawal of heat stress. The LW x Local boars recovered much more rapidly (30-40 minutes) than LW (45 -60 minutes). The LW x Local boars recovered much faster than the LW in most of the semen quality and haematological traits under both durations of exposure. The crossbred pigs retuned to their post exposure values from the 2nd week for boars under 45 minutes exposure and 3rd week for boars exposed for 60 minutes. The LW boars recovered from the 3rd week and 4th week respectively for boars exposed for 45 minutes and 60 minutes. Based on the results recorded, The LW x Local boars appeared to have resisted the thermal stress better than the LW boars and may be suitable for the out-door system of production in this climate than the LW.
TABLE OF CONTENTS
Title Page…………………………………….…………………………………….i
Certification………………………………………………………………………..ii
Dedication……………………………………………………………….………..iii
Acknowledgement…………………………………………………………………iv
Table of Contents…………………………………………………………………………   v
List of Tables…………………………………………………………………………….. ………     ix
List of Plates………………………………………………………………………………………….xii
Abstract…………………………………………………………………….
Chapter One Introduction
- Background of the Study………………………………………………….. .1
- Objectives of the Study…………………………………..…….…………2
- Justification of the Study…………………………………..….………….2
Chapter Two Literature Review
- Effect of High Ambient Temperature of Reproductive Activities of Boars………………………………………………………………….4
- Thermoregulation of Testes in Boars……………………….……………………4
- Techniques for Evaluating the Effects of Heat on Scrotal Animals…………….5
- Effects of High Temperature in Testicular Functions
of Heat Stressed Animals………………………………………………..…….6
- Mechanism of Testicular Cell Damage Caused by Heat Stress………………..9
- Within and Between Genotype Variations in Effects
of Heat on Reproductive Activities…………………………….………………12
- Effect of High Ambient Temperatures on
Semen Quality in Boars…………………………….…………………………….13
- Semen Colour and Consistency………………………………………………………………14
- Semen Volume ……………………………………………………………………………………15
- Sperm Progressive Motility……………………………………………………………………15
- Concentration of Spermatozoa………………………………………………………………..16
- Percentage of Live Spermatozoa……………………………………………………………..17
- Sperm Morphology……………………………………………………………………………….17
- Semen pH……………………………………………………………………………………………19
- Reaction Time………………………………………………………………………………………19
- Ejaculation Time…………………………………………………………………………………..20
- Effect for High Ambient Temperature on
- Haematological Characteristics in Boar………………………………………………20
- ………………………………………………………………………………………….21
2.3.1a Neutrophils…………………………………………………………………………………………22
2.3.1b Eosinophils………………………………………………………………………………………….22
2.3.1c Basophils…………………………………………………………………………………………….22
2.3.1d Monocytes…………………………………………………………………………………………..23
2.3.1e Lymphocytes……………………………………………………………………………………….23
2.3.2 Eryththrocytes………………………………………………………………………………………..24
2.3.3Haemoglobin………………………………………………………………………………………….25
2.3.4 Clinical Application of some Haematological Values…………………………………25
2.3.5 Leucocyte Count……………………………………………………………………………………26
2.3.6 Erythrocyte Count………………………………………………………………………………….27
2.3.7 Haemoglobin Determination……………………………………………………………………28
2.3.8 Packed Cell Volume (PCV) or Haematocrit………………………………………………28
2.3.9 Mean Corpuscular Volume (MCV)…………………………………………………………29
2.3.10 Mean Corpuscular Haemoglobin…………………………………………………………….29
2.3.11 Mean Corpuscular Haemoglobin Concentration (MCHC)………………………..29
2.3.12 Interpretation of Mean Corpuscular Value……………………………………………….30
Chapter Three Materials and Methods
- Location of the Study……………………………………………………………………………31
- Duration of the Study……………………………………………………………………………31
- Experimental Boars………………………………………………………………………………31
- Management of the Boars………………………………………………………………………31
- Training of the Experimental Boars for Semen Collection
with Dummy Sow and Artificial Vagina (AV)………………………………………….34
- Distribution of Boars to Treatments…………………………………………………………35
- The Design of the Study………………………………………………………………………..35
- Semen Collection………………………………………………………………………………….36
- Blood Collection…………………………………………………………………………………..37
- Parameter Measured……………………………………………………………………………..37
- Statistical Analysis……………………………………………………………………………….39
Chapter Four Results and Discussion
- Temperature of Paddocks and Pens………………………………………………………..40
- Rectal Temperatures……………………………………………………………………………..40
- Semen Colour and Consistency………………………………………………………………41
- Total Volume of Ejaculate……………………………………………………………………..41
- Volume of Gel Fraction…………………………………………………………………………43
- Strained Volume of Ejaculate…………………………………………………………………44
- Sperm Progressive Motility……………………………………………………………………45
- Sperm Concentration Per ml………………………………………………………………….48
- Total Sperm in Ejaculate……………………………………………………………………….50
- Live Spermatozoa………………………………………………………………………………..52
- Sperm Abnormalities……………………………………………………………………………53
- Semen pH…………………………………………………………………………………………..55
- Reaction Time…………………………………………………………………………………….56
- Ejaculation Time………………………………………………………………………………….58
- Leucocyte Count………………………………………………………………………………….59
- Erythrocyte Count………………………………………………………………………………..61
- Haemaglobin Concentration………………………………………………………………….63
- Packed Cell Volume (PCV)………………………………………………………………….65
- Mean Corpuscular Volume (MCV)……………………………………………………….67
- Mean Corpuscular Haemoglobin (MCH)……………………………………68
- Mean Corpuscular Haemoglobin Concentration (MCHC)………………….68
Chapter Five Conclusion and Recommendation
5.1 Conclusion………………………………………………………………………………………………71
5.2 Recommendation………………………………………………………………………………………72
References……………………………………………………………………………………………………73
Appendix
Semen Evaluation…………………………………………………………………………………………..92
Haematologiacl Evaluation………………………………………………………………………………94
CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
In some parts of Nigeria, especially the southern parts, farmers keep indigenous and exotic pigs outdoors during the day to search for food. These pig farmers have a target which is to save money (Bull, 1997; McGlone, 1998). However, in these areas which have humid tropical climate, pigs are mostly exposed to ambient temperatures above their thermo-neutral zone during the day (Curtis 1992; McGlone, 1998) while at night they are kept indoors when the ambient temperatures are somewhat near their thermo-neutral zone. Despite this diurnal variation in ambient temperatures, pigs in these areas still survive and reproduce, but the temperature variation to which they are exposed constantly tend to significantly affect their reproductive performance (Ayo et al., 1996), semen quality (McNitt and First, 1970; Wettemann et al., 1976), and haematological status (Schalm et al., 1975; Coles 1986).
Generally, reproductive performance of boars is reduced during the hot season (Ayo et al., 1996; Hahn, 1999; Ugwu and Nwakalor, 2007). Exposure of boars to increased ambient temperatures results in the reduction of semen quality (Setchell, 1998). This decrease in semen quality of boars during heat stress may be associated with reduced pregnancy rates (Setchell, 1998; Walters et al., 2005) and increased embryonic mortality (Zhu and Setchell, 2004; Zhu et al., 2004). Exposure of boars to increased ambient temperature for 3 days caused a reduction in semen quality that persisted for 6 to 8 weeks after treatment (Setcell, 1998; Zhang, 2006). Similarly, fertility was reduced in rams after short-term exposure of whole body to increased ambient temperatures (Hafez 1993). Also, exposure to high ambient temperatures influences the erythrocytes and hemoglobin concentrations (Coles, 1986; Connor and Orzechowski, 2001) as well as packed cell volume (Schakm et al., 1975). The effects of exposing boars to tropical solar radiation as is the case in the humid tropical climate have not been substantially studied.
Therefore, the present research is undertaken to determine the semen quality, haematological characteristics, libido and body temperature regimes of exotic and crossbred boars exposed to tropical solar radiation for 45 and 60 minutes.
1.2Â Â Â Â Â Â Objectives of the Study
The general objectives of this study is to determine the effect of 45 and 60 minutes exposure of Large White x Local (LW x Local) crossbreds and Large White (LW) boars to tropical solar radiation on their body temperature regimes, libido, ejaculate characteristics and hematological parameters.
The specific objectives of the study are:
- to determine the effect of exposing LW x Local and LW boars to different durations of solar radiation on their normal body temperature pattern;
- to determine the effect of the exposure on ejaculation reaction time of the two genotypes;
- to compare the characteristics of the ejaculates of the two exposed genotypes;
- to compare the effect of the exposure on haematological profile of the two boar genotypes; and
- to find out the time of full recovery to normal semen quality and haematology in the two genotypes after exposure to tropical solar radiation.
Â
1.3Â Â Â Â Â Â Justification of the Study
The reproductive efficiency of pigs in tropical countries like Nigeria tends to fluctuate. This may be because of the seasonal and diurnal variation in prevailing temperatures which causes adverse changes in the growth and reproductive pattern of pigs (Samisoni and Blankshaw, 1971; Hafez, 1993) and haematology (Schalm, 1975; Coles, 1986). These changes are accompanied by poor quality semen and low fertility rate. The consequences of this problem are obviously grave in southern parts of Nigeria where ambient temperatures, coupled with high humidity, occur throughout the year and more so with the present adverse global climate change.
The management of boars to ensure good sperm production under different environmental conditions is a major concern for swine keepers in tropical countries and countries where there are extreme environmental changes. Such changes create stress in boars and negatively influence the production of spermatozoa (Egbunike and Dede, 1980; Matswki et al., 2003). High temperature during dry season may result in lower feed consumption and create stress that may result in the alteration of spermatogenesis (Steinbach, 1971; Ayo et al., 1996). However, management strategies such as good housing, proper mating conditions and normal mating frequency, may be useful in facilitating production of good quality semen and sustaining good reproductive efficiency in hot climates.
Also, high temperature as obtained during dry season may adversely influence haematological traits such as erythrocyte count (Coles, 1986); hemoglobin concentration (Hb) (Schalm, 1975; Coles, 1986; Santoro and Faucitano, 1996) and packed cell volume (PCV) (Schakm, 1975; Cheesbrough, 1991).  Other factors that affect the blood picture of pigs are diet (Edwards 1985), water intake and feed restriction (Hill and Powell, 1975; Graf, 1984; Esonu, 2000).
In general, thermal stress during hot seasons is an unwholesome development in swine industry of the tropics. Â There is, therefore, the need to conduct studies to determine the effects of daily stress due to persistent solar radiation on two genotypes of boars mainly reared in this part of the humid tropics.
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