Nigerian J. Anim. Sci. 2018, 20 (2): 1-5 Frequencies of the Transferrin Alleles and Genotypes in West African Dwarf Goats of Southwestern Nigeria 1 Awobajo, O. K., 2 Salako, A. E., 2 Osaiyuwu, O. H., and 2 Akinyemi, M. O. 1 Department of Agricultural Science, Tai Solarin University of Education, P. M. B. 2118, Ijebu-Ode, Ogun State, Nigeria. 2 Animal Breeding and Genetics Laboratory, Department of Animal Science, University of Ibadan, Ibadan, Nigeria. 1 Corresponding author’s email: koyakola@gmail.com Abstract The aim of this study was to determine the frequencies of Transferrin alleles and genotypes in West African Dwarf (WAD) goat. 140 adult WAD goats, maintained in four Southwestern States of Nigeria were used in the study. The polymorphism of transferrin was determined using Cellulose Acetate electrophoresis technique. It was found that the transferrin was controlled by two codominant alleles (TfA and TfB) in WAD goats. These two alleles, because of the codominant nature of inheritance, control the occurrence of three transferrin genotypes in the analyzed populations. The first two (TfAA and TfBB) were homozygous while the third one (TfAB) was heterozygous. The TfAB genotype was predominant with frequency of 0.90, 1.00, 0.87 and 0.55 in Ogun, Ondo, Osun and Oyo States respectively with a mean frequency of 0.83±0.20 while TfBB genotype was least common except for population from Osun State with a frequency of 0.05, 0.00, 0.22 and 0.15 in Ogun, Ondo, Osun and Oyo States respectively with a mean frequency of 0.08±0.07. The frequencies of transferrin alleles were 0.50, 0.50, 0.45 and 0.58 for TfA and 0.50, 0.50, 0.55and 0.43 for TfB in Ogun, Ondo, Osun and Oyo States respectively with a mean frequency of 0.49±0.05. Transferrin system showed genetic equilibrium in the analyzed population (χ2 value = 1.780). The observed heterozygosity was 0.91, 1.00, 0.87 and 0.55 43 in Ogun, Ondo, Osun and Oyo States respectively with a mean frequency of 0.84 and average Fis value of -0.67. Keywords: Cellulose Acetate electrophoresis technique, Genotypes, Polymorphism, Transferrin alleles, West African Dwarf goat. Description of Problem The importance of genetic diversity in livestock is directly related to the need for genetic improvement of economic traits as well as facilitates rapid adaptation to potential changes in breeding goals (3). Studies of genetic diversity are useful to the understanding of evolution of breeds, gene pool development and the level of differentiation among breeds (3, 4, 6). Several goat breeds have been evaluated for genetic variation based on morphological, physiological, pathological, productive, reproductive and behavioral features (15, 17). However, these are influenced by environmental factors. The gene frequencies of haemoglobin and transferrin types are thought to be related to breeds and geographical distribution (9) and are used in studies of genetic variation within and between breeds. Transferrin is ß-globulin, which is characterized by its specific ability to reversibly bind iron and various other metal ions. Generally, it exhibits a high degree of polymorphism and belongs to the well-studied systems in man and different animal species UNIV ERSIT Y O F IB ADAN L IB RARY mailto:koyakola@gmail.com (19). Genetic studies on Transferrin polymorphism have been conducted in many countries and in different species, such as goats and sheep in China, Argentine, Japan and Nigeria (1, 7, 8, 10, 13). Red Sokoto (Maradi) goat is a major breed found in Northern part of Nigeria, reputed for its high quality skin that is used in the leather industry locally and internationally (2). Several studies have been carried out on the phenotypic variation in goat breeds (23); these traits are however under the influence of the environment and not a true reflection of the genetic constitution of these breeds. This paper is therefore aimed at describing the distribution of transferrin alleles and genotypes within the West African Dwarf goat of Southwestern states of Nigeria. Materials and Methods One hundred and forty (140) animals, twenty from each sampling area comprising Ijebu- Ode and Ado – Odo, (Ogun state), Ondo, (Ondo state), Ile –Ife, Osogbo and Iwo, (Osun state), and Ibadan, (Oyo state), were randomly selected. Blood was collected from each animal by jugular venipuncture and placed in heparinized tubes to prevent coagulation. Farmers raised these goats under traditional systems. Sample Analysis 5 ml of blood was drawn into tube containing Lithium Heparin as anticoagulant. Blood plasma was separated from blood cell by centrifugation at 3500 rpm at room temperature for 10 minutes. Blood plasma was drawn into labeled sample tube after centrifugation and stored in the freezer until tested. Cellulose Acetate Electrophoresis was performed according to (16) with minor modifications. Band scoring was carried out to visualize the protein bands at the transferrin (Tf) locus. The Electrophoresis condition was as shown in Table 1. Table 1: Cellulose Acetate Electrophoresis Conditions for Transferrin. Sample Buffer Time pH Voltage Stain Destain 0.6μl Plasma undiluted Tris glycine 20 mins 8.5 150 Ponceau stain 5% acetic acid Statistical Analysis Allelic variants or allozyme bands were marked in the order of increasing mobility, allele A being the allele with the slowest mobility. Allele frequencies and genotypic frequencies were computed by direct gene counting method and tested for fit to Hardy- Weinberg (HW) ratios using chi square test (χ2 goodness– of – fit test). The observed and expected heterozygosity (Ho and He) were calculated according to (12). All computations were performed using Popgene Programe (24) and Tools for Population Genetic Analyses (11). Results and Discussion The results of allele frequencies of transferrin are presented in Table 2. Observation of the transferrin band in WAD goat showed that two codominant alleles were present at the transferrin locus; these are Tf A and Tf B . These two alleles controlled three genotype of transferrin (Tf AA , Tf AB and Tf BB ) as autosomal codominant (Table 3). This result was parallel to the findings of (20) that reported the results of study in five breeds of goat in USA and found the Tf A and Tf B . (9) in an experiment to detect haemoglobin and transferrin polymorphism in Damascus goats using starch gel electrophoresis reported that nine transferrin genotypes, namely Tf AA, AC, AD, BB, BC, BD, CC, CD and DD exists, in which C and D are the two common occurring allele at the β locus and A is the rare β- globulin variant. In this current study allele Tf AB was most frequently occurring in the Awobajo et al 2 UNIV ERSIT Y O F IB ADAN L IB RARY studied population, whereas the allele Tf BB was the rare β-globulin. The higher frequency of Tf AB genotype observed in this study is similar to the frequency of Tf AB genotype in the Italian Alpine goat, Sannen (22), Bambari from India (5), Sannen from USA (14). Wright' F- statistics (Table 2) result with average Fis of - 0.6804 indicated excess of heterozygosity at the Tf locus in WAD goat population. The observed heterozygosity in this breed could be explained by overlapping generations, mixing of populations from different geographical locations, natural selection in favour of heterozygosity or subdivision accompanied by genetic drift (18). Table 2: Allele Frequency and Fis of WAD goats at Transferrin Locus. Alleles Frequency FIS TfA 0.51 -0.6804 TfB 0.49 -0.6804 Total -0.6804 Wright's (1978) fixation index (Fis) as a measure of heterozygote deficiency or excess. Table 3: Genotype Frequencies and test of Hardy-Weinberg equilibrium at Transferrin locus in WAD Goats. Genotype Frequency Obs. (O) Exp. (E) (O-E)²/E AA 0.09 09 30.1325 14.8207 AB 0.83 105 62.7349 28.4743 BB 0.08 11 32.1325 13.8982 Chi-square test for Hardy-Weinberg equilibrium: Chi-square: 1.7799 Degree of freedom: 3 Probability: 0.619329 Table 4: Expected homozygosity and heterozygosity at Transferrin locus. Obs_Hom Obs_Het Exp_Hom* Exp_Het* Nei** Ave_Het 0.1600 0.8400 0.4981 0.5019 0.4999 0.4961 Observed heterozygosity (Ho =0.8400) and expected heterozygosity (He =0.5019) values are presented in Table 4. The value of expected heterozygosity obtained in this study (0.8400) indicated genetic variation in transferrin locus in WAD goats. By implication, selection programme if carefully planned and executed will result in genetic gain towards improved performance in the select populations. Chi- square test (1.7799) did not show significant differences between the observed and expected genotype values in the transferrin locus of WAD goat, this means that the WAD goat population is a random mating population. Conclusion and Application In this work we have demonstrated that: 1. WAD goat genetic diversity is still conserved. 2. Two codominant alleles were identified (TfA and TfB) in the WAD goat. Awobajo et al 3 UNIV ERSIT Y O F IB ADAN L IB RARY 3. 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