Genetic distance between two popular Nigerian goat breeds used for milk production

A O Adebambo, Olufunmilayo Adebambo, J L Williams*, Sara Blott* and Barbara Urquart*

Dept of Animal Breeding and Genetics, University of Agriculture, Abeokuta, PMB 2240, Abeokuta Nigeria
tumininuadebambo@yahoo.com
* Roslin Institute, Midlothian EH25 9ps, Roslin, Scotland

Abstract

A panel of 21 microsatellites markers selected from bovine and caprine was used to study diversity between the Maradi and West Africa Dwarf goat DNA as a preliminary study for sustainable milk production in South West Nigeria. All the 21 markers were successfully amplified by Polymerase Chain Reaction (PCR) and they were tested for polymorphism. The study showed that genetic distance between Western African Dwarf goat and Maradi was 0.39.

Key words: diversity, microsatellite, Maradi, West African Dwarf

Introduction

Livestock production is vital to subsistence and economic development (Winrock International 1992). The ever increasing demand for livestock production to cater for the nutritional needs of rapidly growing human population has led to indiscriminate crossbreeding in an effort to improve productivity. Nigeria has 53.8 million goat population (FAOSTAT 2009) which constitute an important source of milk and meat for local consumption and hide for export market.

The Maradi goat is especially noted for its good skin which serves as good economic return apart from being a good milk animal among the Nigerian Fulani cattle herdsmen. The economic importance of livestock in African farming systems increases with decreasing rainfall (Winrock International 1992). The Fulani herdsmen suffer an annual loss in production during the dry season, to sustain themselves and their animals there is an annual exodus to the southern part of Nigeria in search for pasture during the dry season. While some go back up north during the wet season; some have remained sedentary at the south. The need to stay down south has led to indiscriminate crossbreeding in order to keep and sustain the Maradi in the Southern Nigeria environment; a rain forest region prevailing in diseases like trypanosomiasis. To achieve sustenance the Maradi goat is crossed with the well adapted West African Dwarf goat which is indigenous to the southern Nigeria. This creates a new line of goats both good in milk production at same time trypanotolerant. Both goats are endowed with unique qualities such as water economy, heat tolerance, disease resistance, mothering and walking abilities, and the ability to efficiently metabolize low quality feeds (Muema et al. 2009). The present research studies genetic diversity of the Maradi and West African Dwarf goats and their crosses being used in sustainable milk production program in South Western Nigeria. 
 

Material and methods

One hundred and thirty eight unrelated individual goats from two different breeds: Maradi (Mar) a Northern breed, West African Dwarf (WAD) a Southern (Forest zone) breed and crossbreeds of both were used to estimate the allelic frequencies of each microsatellite.

The selection was random with at least 100km distance between selection points to maintain sampling of unrelated animals. DNA was prepared from 7ml blood collected into vacuteiner tubes, from the jugular vein of the animals.

Twenty one microsatellite markers used in this study were selected from bovine and caprine markers recommended by the International Society for Animal Genetics and Food and Agriculture Organisation (ISAG/FAO) advisory group on animal genetic diversity for use in chicken biodiversity studies (Hoffman et al. 2004).

PCR conditions

The PCR conditions were as described by ISAG/FAO recommendations (Hoffman et al 2004). Allelic frequencies were estimated from a panel of 61 Maradi, 43 West Africa Dwarf and 34 WAD x Mar cross animals. DNA was prepared from 7ml blood, transported to buffy coat in equal volume of Urea/Tris/EDTA to Roslin Institute for amplification and analyses.

PCR typing was carried out on 50ng of the genomic DNA in a 10µl reaction, comprising 10pM each of fluorescently labeled PCR primers, 1µl of PCR buffer (Amersham) 20µM each of dCTP, dGTP, dTTP and dATP, 0.5 units of Taq polymerase per reaction and 1.5-3.0 µl of MgCl₂ depending on the primer. The mixture was cycled on the Hybaid Omnigene thermal cycler with cycling conditions of 3 mins of initial denaturation at 93.5°C followed by 30 cycles at 94°C, 30 secs at annealing temperature of 50-65°C and 30 secs and final elongation at 72°C for 9 mind.

Multiplexing was carried out following the recommendations of the ISAG/FAO panel. Genotyping was carried out using the ABI 3730XL automated capillary sequencer using the Liz 500-350 internal lane size standard to size fractionate all amplified products. Allele size calling and binning was done with the aid of GeneMapper 3.5 (Applied Biosystems).
 

Results and Discussion

Table 1 show that the markers are all polymorphic and can be used to determine diversity in the goat breeds. Examples of disparate diversities are given by the microsatellites which were shown to be highly polymorphic with allele sizes ranging from 5 to 24 in the goats (Table 1). Haberfeld et al (1991) recorded an average number of alleles as 21.4 for sheep and Selvam et al (2009) recorded a range between 7 and 19 for Madras red sheep all indicating high polymorphism and heterozygosity.  The microsatellite markers Hel 1, CSSM 66 and TGLA 53 showed high allelic numbers in the goats 24, 23 and 22 respectively.

 Percentage heterozygosity among the goats range from 0.46-0.55. This is similar to the 0.51 recorded by Muniyandi et al (2009) for the water buffalo, Bubalus bubalis. The number of alleles and homozygosity are shown in Table 2.

Plotting the dendogram of these frequencies confirmed the divergence of these goat breeds (Figure 1) although with just 3-breeds under consideration, the bootstrap values could not be calculated. Nevertheless the ecological divergence of the breeds is still confirmed with the Western African Dwarf being genetically distant from the Maradi by the value of 0.39 (Table 3). Among some Spanish sheep breeds the percentage heterozygosity ranged from a minimum of 0.30 to a maximum of 0.89 (Arranz et al 2001) and were comparable with those observed in Garole sheep (Sodhi et al 2003) and Nilagiri sheep (Haris et al 2007).

Figure 1. Genetic distance rooted trees (Cavalli-Sforza) among individual goats

Genetic diversity using microsatellite marker shows that crossing of these two goat breeds presents enough diversity to generate good heterotic advantage and combining abilities. 

Acknowledgement

The authors are sincerely grateful to the World Bank and the corresponding National Agricultural Research Projects in Nigeria, the Royal Society of England and Roslin Institute for the sponsorship of this research.
 

References

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Received 12 August 2010; Accepted 13 November 2010; Published 1 February 2011

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