ABSTRACT
An experiment was conducted to predict semen traits from biometric and secondary sexual traits in lines of Shikabrown @ parent stock chickens. A total of 30 roosters (52 weeks old), 15 each from the dam and sire lines were used for the study. For the effect of mating ratio on egg fertility and hatchability, a total of 15 roosters were mated to 90 hens in the dam and sire lines at mating ratio 1:3, 1:6 and 1:9, and a total of 1711 fertile eggs were hatched in three sets. Biometric traits (body weight-BW, body length-BL, breast girth-BG, drumstick length-DSL and shank length-ShL); secondary sexual traits (comb length-CL, comb width-CW, wattle length-WL and wattle width-WW); semen characteristics (semen colour-SC, semen volume-SV, semen pH, sperm motility-SM, sperm concentration-SCo and sperm live ratio-LR) and sperm morphology defect traits (dead ratio-DR, free tail-FT, bent tail-BT, detached head-DH and coiled tail-CT) were evaluated. Number set-NS, number fertile-NF, number infertile-NI, number hatched-NH, percent fertile-PF, percent infertile-PI, percent hatched-PH and percent hatchability-PTH traits were also measured. Data collected were subjected to ANOVA, correlation and regression procedure of SAS, with significant means separated by DMRT procedure. From the results obtained for biometric traits, significant (p<0.05) difference was obtained for BW, BL, DSL and ShL in sire line roosters. Significant (p<0.05) difference was observed for CL, CW and WL for secondary sexual traits in the dam line roosters. High coefficients of variation of 31.76 (SV) in the dam line, and 38.09 (SC) and 39.48 (SV) in the sire line were obtained in this study. The results also showed significant differences (p<0.05) for SC and SCo in the dam line, and semen pH in the sire line. FT and DH were significant (p<0.05) in the sire line. Total sperm morphology defect of 31 % and 29 % were obtained for the dam and sire line roosters respectively. Results obtained for correlation showed significant (p<0.05, p<0.01,
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p<0.001) correlation for some of the traits measured. For the prediction of semen traits from biometric traits in the dam line showed low coefficients of determination (R2) of between 9 % and 28 % in the dam line, and between 9 % and 27 % in the sire line. For prediction of semen traits from secondary sexual traits, coefficients of determination (R2) of between 3 % and 13 % were obtained in the dam line, and between 2 % and 28 % in the sire line. Result for hatching traits showed significant (p<0.05) difference for all traits measured in both lines. Mating ratio affected (p<0.05) hatches in the dam and sire lines. However, weight of day-old chicks was not affected by (p>0.05) mating ratio in both lines. In conclusion, roosters of the sire line were best for BW (5.52 kg), BL (72.89 cm), DSL (16.13 cm) and ShL (10.73 cm). Positive and significant correlation coefficients of 0.36 (BW and LR), 0.32 (BL and SV), 0.36 (BL and LR) and 0.29 (WW and SCo) in the dam line were obtained. For the sire line, significant positive correlation coefficients of 0.42 (BL and LR), 0.36 (BW and LR) and 0.30 (ShL and SCo) were obtained. High coefficients of variation were obtained for SC (31.76) in the dam line, and SC (38.09) and SV (39.48) in the sire line roosters. Sperm morphology defects of 31 % and 29 % were obtained in the dam and sire line roosters respectively. For the dam line, best PF (89.10 %) was observed in mating ratio 1:3, while best PH (62.67 %) and PTH (72.40) were observed for ratio 1:6. In the sire line, best PF (95.40 %), PH (69.37 %) and PTH (72.83 %) were observed for mating ratio 1:6. It is therefore recommended that the sire line roosters be considered for upgrading of local chicken flock. Alternatively, body measurements (BW, BL, WW and ShL) should be considered in the selection of roosters of good semen quality. Potential still abounds for genetic improvement of SV in the dam line, and SC and SV in the sire line roosters, with younger roosters preferred for enhanced fertility. Also, mating ratio of one cock to six hens (1:6) should be adopted for better hatchability of eggs in laying chicken strains.
TABLE OF CONTENTS
TITLE PAGE………………………………………………………………………….ii DECLARATION……………………………………………………………………….iii CERTIFICATION…………………………………………………………………….iv DEDICATION………………………………………………………………………….v ACKNOWLEDGEMENTS………………………………………………………….vi TABLE OF CONTENTS……………………………………………………………..viii LIST OF TABLES…………………………………………………………………….xii ABSTRACT……………………………………………………………………………xiv CHAPTER ONE………………………………………………………………………..1
1.0 INTRODUCTION………………………………………………………………….1
1.1 Justification…………………………………………………………………………..3
1.2 Statement of Hypotheses…………………………………………………………….4
1.3 Objectives……………………………………………………………………………5
CHAPTER TWO……………………………………………………………………….6
2.0 LITERATURE REVIEW………………………………………………………….6
2.1 Fertility and Hatchability…………………………………………………………6
2.1.1 Nutritional factors………………………………………………………………..6
2.1.2 Breed, age and sex factor…………………………………………………………7
2.1.3 Incubation factor…………………………………………………………………8
2.1.4 Climatic factor………………………………………………………………….10
2.1.5 Egg factor………………………………………………………………………11
2.2 Semen Trait Evaluation in Cocks…………………………………………………..12
2.3 Relationship Between Semen Trait with Biometric and
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Secondary Sexual Trait…………………………………………………………….12 2.4 Effect of Mating Ratio on Reproductive Traits…………………………………13 CHAPTER THREE……………………………………………………………………16 3.0 MATERIALS AND METHODS……………………………………………..16 3.1 Experimental Location…………………………………………………………16 3.2 Experimental Animals and Management………………………………………16 3.3 Data Collection…………………………………………………………………21 3.3.1 Body measurement……………………………………………………………..21 3.3.2 Measurement of secondary sexual traits………………………………………..21 3.3.3 Semen collection……………………………………………………………….22 3.3.4 Hatching traits ………………………………………………………………….23 3.4 Incubation and Hatching Procedure……………………………………………24 3.5 Statistical Analysis……………………………………………………………..25 CHAPTER FOUR…………………………………………………………………….27 4.0 RESULTS………………………………………………………………………27 4.1 Means and Coefficients of Variation for Body Weight and Biometric Traits at week 52………………………………………………..27 4.2 Means and Coefficients of Variation for Secondary Sexual Traits……………………………………………………………………27 4.3 Means and Coefficients of Variation for Semen Characteristics…………………………………………………………………..28 4.4 Means for Sperm Morphology Defect………………………………………….28 4.5 Least Square Means for Hatching Traits in Lines of Shikabrown @ Parent Stock at Varying Mating Ratio……………………….29 4.6 Least Square Means for Day-old Weight (g) of Chicks at Varying Mating Ratio in Lines of Shikabrown @ Parent Stock……………………………………………………………………………33 4.7 Effect of the Interaction of Mating Ratio and Hatch on Day-old Weight (g) of Chicks in Lines of Shikabrown @ Parent Stock……………………………………………………………………………33
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4.8 Coefficients of Correlation of Body Weight, Biometric and Semen Characteristics in the Dam and Sire Lines………………36 4.9 Coefficients of Correlation of Body Weight, Biometric and Sperm Morphology Defect in the Dam and Sire Lines……………………38 4.10 Coefficients of Correlation for Secondary Sexual Traits and Semen Characteristics in Dam and Sire Lines………………………40 4.11 Coefficients of Correlation for Secondary Sexual Traits and Sperm Morphology Defect in the Dam and Sire Lines……………………42 4.12 Coefficients of Correlation for Body Weight, Biometric Traits and Secondary Sexual Traits in the Dam and Sire lines…………………44 4.13 Multiple Regression Equation for Prediction of Semen Characteristics from Body Weight and Biometric Traits………………………46 4.14 Multiple Regression Equation for Prediction of Semen Characteristics from Secondary Sexual Traits…………………………………46 CHAPTER FIVE………………………………………………………………………49 5.0 DISCUSSIONS………………………………………………………………..49 5.1 Coefficients of Variation for Body Weight, Biometric , Secondary Sexual Traits and Semen Characteristics in Lines of Roosters of Shikabrown @ Parent Stock at Week 52………………49 5.2 Mean Values for Body Weight, Biometric and Secondary Sexual Traits in Lines of Shikabrown @ Parent Stock at Week 52…………….49 5.3 Mean Values for Semen Characteristic Traits in Lines of Shikabrown @ Parent Stock at Week 52…………………………………….50 5.4 Mean Values for Sperm Morphology Defect in Lines of Shikabrown @ Parent Stock at Week 52…………………………………….51 5.5 Effect of Mating Ratio on Hatching Traits in Lines of Shikabrown @ Parent Stock………………………………………………….52 5.6 Effect of Interaction of Mating Ratio and Hatch on Day-old Weight (g) of Chicks in Lines of Shikabrown @ Parent Stock……………………………………………………………………………53 5.7 Coefficients of Phenotypic Correlation for Body Weight, Biometric, Secondary Sexual Traits and Semen Characteristics in Lines of Shikabrown @ Parent Stock………………………..53
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5.8 Multiple Regression Equation for Prediction of Semen Characteristics from Biometric and Secondary Sexual Traits………………….54 CHAPTER SIX………………………………………………………………………..56 6.0 SUMMARY, CONLUSIONS AND RECOMMENDATIONS……………..56 6.1 Summary………………………………………………………………………..56 6.2 Conclusions………………………………………………………………………58 6.3 Recommendations……………………………………………………………..59 REFERENCES………………………………………………………………………..60
CHAPTER ONE
1. 0 INTRODUCTION
Domestic chickens contribute highly to the socio- economic condition of Nigerians. A survey reported the population of backyard poultry in Nigeria to be about 84 million, which amounts to about 60 % of the total poultry population in Nigeria (Jesuyon and Salako, 2013). The poultry industry in Nigeria has undergone a significant boost, from household oriented husbandry to modern and large-scale poultry industry, which can be found in the urban centers today (CBN, 2006). Though the value of livestock resources has grown steadily in recent years, the overall contribution of this sector to agriculture remains relatively low (CBN, 2006). Animal protein supply in Nigeria, especially meat and egg is expensive, inadequate and often out of reach of the majority of the populace. This effect is felt more by a large proportion of the rural population, which constitute over 70 % of the Nigerian population and form over 85 % of the extreme poor in the country (Chukwuji et al., 2006). Animal protein deficiency and a continuous rise in population necessitated the need to exploit different animal protein sources, one of which is the poultry industry towards meeting these needs. Shikabrown layer type breed was developed in Nigeria, at the National Animal Production Research Institute, after being tested for adaptability in the six geo-political zones of the country (Kallah, 1999). The breed was developed from a collapsed population of Rhode Island Red and White egg type chickens imported into the country in 1985, following continuous selection (Adeyinka, 1998).
Selection of cocks of high semen quality is an important practice in breeding programmes, and the evaluation of semen quality characteristics is an important
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indicator of the reproductive potentials of males, reported to be the major determinant of egg fertility and hatchability of chickens (Peters et al., 2004). Evaluation of the reproductive potentials of males is also needed in the prediction of fertility in natural mating and artificial insemination programmes. The fertilising ability of the breeder cock depends upon several semen quality characteristics, which include sperm concentration, viability and motility (Parker et al., 2000). Sperm motility has been reported to be an essential parameter for normal fertilisation, which is an indirect measure of metabolic activity and sperm viability (Berlinguar et al., 2009). Semen quality is also determined by volume of ejaculates, sperm concentration, sperm motility, percent live sperm and sperm morphology. Sperm morphology plays a very important role in fertilisation process, influenced by nutrition, season, climatic factors, physiology and genetic make up (Dana et al., 2000). Any form of sperm morphological defect is an indicator of decreased fertility in most animal species (Chandler et al., 1988), with defect of up to 20 % leading to a reduced fertility (Morrow, 1980). The findings of Reddy et al. (1975) showed a negative correlation between abnormal sperm and conception rate. An accurate sperm morphology examination assists animal breeders to eliminate male animals of low fertility prior to natural mating or artificial insemination programmes (Rodriguez-Martinez and Barth, 2007).
Knowledge of correlation between semen traits and other traits such as weight, age, body condition and testicular size could serve as important indicator of the reproductive potentials of males in ruminants (McGary et al., 2003). Positive correlation between wattle length, comb length and fertility also indicates that the development of secondary sexual characters may reveal male reproductive quality in some genetic strains (McGary
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et al., 2003). The importance of evaluating semen in poultry breeding either for selection of breeder males, or for routine check of their reproductive potentials has also been emphasised in the report of Cheng et al. (2002). In their report, Galal et al. (2000) noted that genes that govern length of shank, comb and wattle would tend to be inherited linked with genes controlling ejaculate volume and sperm concentration, but independently of those controlling sperm motility and abnormal sperms. 1. 1 Justification Several studies (Hossari, 1980; El-Sayiad et al., 1994; Abdellatif, 1999) have recommended the use of comb length and wattle length as good indicator traits for selection of some quantitative traits in chickens. Larger combs may reliably point to roosters with greater semen production, higher androgen levels (Gilbert, 1971) or increased mating activity (Ligon et al., 1990). The most precise technique for the evaluation of semen is by microscopic examination in the laboratory. However, this method exposes birds to stress, infringes on animal welfare and requires expensive facilities and expertise. Thus, indirect method of estimating semen traits, based on the correlated response traits will serve as an alternative in the selection of males of good semen quality (Galal, 2007).
The success of the sustenance of poultry production chain depends on regular and constant supply of day-old chicks; with commercial poultry operators relying on hatcheries for the supply of day-old chicks for production (Stromberg, 1975). Mating system, age of eggs, egg storage condition, flock age, husbandry and rearing practices, incubator temperature and relative humidity and egg turning are among the several factors affecting poultry egg hatchability (Brah and Sandhu, 1989; Tarongoy, et al., 1990; Weis, 1991; Gebhardt-Henrick and Mark, 1991; Buhr, 1995 and Permsak, 1996).
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Reports have also shown poor egg storage, prolonged egg storage, breeder age, incubation problems, genetic effect of breeds, varieties and individuals within breeds as potential factors leading to poor egg fertility and hatchability (Fairchild et al., 2002; Islam et al., 2002). From the findings of Orunmuyi et al. (2013) on hubbard broilers, mating ratio 1:6 gave the best egg fertility and hatchability for pedigree hatching of chicks. Several works have been conducted on semen characteristics and the effect of mating ratio for pedigree hatching of chickens, but no work has been done on the effect of mating ratio on pedigree hatching of Shikabrown @ parent stock. This is the main thrust of this research. 1. 2 Statement of Hypotheses Null Hypothesis (Ho): Body weight, biometric and secondary sexual traits cannot be used as indicator traits to predict semen traits in lines of Shikabrown ® parent stock (roosters). Alternative hypothesis (Ha): Body weight, biometric and secondary sexual traits can be used as indicator traits to predict semen traits in lines of Shikabrown ® parent stock (roosters). Null hypothesis (Ho): Mating ratio has no association with egg fertility and hatchability in lines of Shikabrown ® parent stock. Alternative hypothesis (Ha): Mating ratio has association with egg fertility and hatchability in lines of Shikabrown ® parent stock. Null hypothesis (Ho): Mating ratio has no association with day-old weight (g) of chicks in lines of Shikabrown ® parent stock.
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Alternative hypothesis (Ha): Mating ratio has association with day-old weight (g) of chicks in lines of Shikabrown ® parent stock. 1. 3 Objectives The broad objective of this study is to evaluate the reproductive performance of Shikabrown ® parent stock chickens. The specific objectives include:
1. To determine the association of semen traits with body weight, biometric traits and secondary sexual traits in lines of roosters of Shikabrown ® parent stock chickens.
2. To evaluate the semen characteristics and sperm morphology defects in roosters of lines of Shikabrown ® parent stock chickens.
3. To evaluate the effect of mating ratio on egg fertility and hatchability and weight (g) of day-old chicks in lines of Shikabrown ® parent stock chickens.
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