Visible genetic profile and genetic distances of local goat populations in Albania

Vilson Bozgo, Anila Hoda, Ylli Biçoku and Rexhep Bajramaj*

Faculty of Agriculture and Environment, Agricultural University of Tirana, Albania
hodanila@yahoo.com
* Faculty of Veterinary Medicine, Agricultural University of Tirana, Albania

Abstract

Local goats are an important livestock species, in the mountainous area of Albania. The aim of this study was the characterization of Hasi (83) Bulçar (75), çekin (48), Peza (62) and Velipoja (60) goat populations based on visible genetic profile. A total of 328 randomly sampled animals of both sexes were analyzed to investigate the distribution and allelic frequencies in each population for different morphologic traits (hair length, horns, wattles, beard, and coat color) are used to establish Nei genetic distance and for the construction of NJ consensus tree.

The allelic frequencies for wild ear (El⁺), horn (Ho⁺), wattle (Wa^w), beard (Br^b) presence, long hair (Hl^L), roan color (Rn^R) and brown eumelanin (B^b), for the whole goat population were 0.950, 0.955, 0.301, 0.969, 0.07, 0.216 and 0.752. Heterozygosity values at population level ranged from 0.15 (Velipoja) to 0.26 (Çekin). Hasi was the population with the highes level of polymorphism, but Peza displayed the lowes level of polymorphism. The smallest distance was between Velipoja and Peza populations. The principal component analysis (PCA) was carried out. In the future the study has to go further, using molecular markers. 

Key words: allele frequency, Nei genetic distance, PCA

Introduction

Albania is a Mediterranean country on the West Balkan Peninsula in the south east of Europe. Goats are one of the most important livestock species, especially for hilly and mountainous area of Albania. The system of production is extensive. The animals are kept based on the traditional methods, principally through the exploitation of the natural pastures and the spontaneous flora resources. The cultivated pastures and concentrated feed provide a small percentage of the feed requirements. The goat genetic fund is composed of the local indigenous populations and different ecotypes are distinguished. Because of the systems of production, the level of the production is relatively low, about 80-90 kg milk/goat/year (Petushi et al 2008). 

The characterization of Albanian local goat’s populations is of great interests for genetic improvement and conservation of animal genetic resources. The aim of this study was to characterize some important local goat populations in Albania based on their visible traits. Similar studies have been carried out  for French goat population cit_bf( Lauvergne et al 1987), goats of Ceará State (Brazil) and goats of the Mediterranean region (Machado et al 2000), local Criollo goat population in Patagonia Argentina (Lanari et al 2003), goat of Pernambuco (Oliveira et al 2006), goats of Tunisian oasis (Nafti et al 2009), Nigerian goat populations (Yakubu et al 2010) cit_af ref_bf(Lauvergne, 1986 ref_num281 / Lauvergne, 1987 #278 / Machado, 2000 #279 / Lanari, 2003 #282 / Oliveira, 2006 #277 / Nafti, 2009 #283 / Yakubu, 2010 #289)ref_af. The aim of this study is to provide information on visible genetic profile in some important traditional goat populations. 

Material and methods

A total of 328 randomly sampled animals of both sexes, from five local goat populations were analyzed. The individuals were selected from different random farms from the location of the origin of the breed. A sample of 10-15 randomly selected flocks per each breed was examined. The records were taken from 5-10 randomly chosen individuals per flock. All the individuals were unrelated and older than 2 years. The breeds were marginally farmed and autochthones. The populations were from Hasi (83) Bulçar (75), çekin (48), Peza (62) and Velipoja (60). The Hasi goat is the larger mountain version of the Albanian breed. Found in northeastern Albanian in the region surrounding Kukesi. The breed is kept for both milk and meat production, reddish in coloration with lop ears cit_bf(Mason 1996)cit_af ref_bf(Mason, 1996 ref_num285)ref_af. Velipoja goat is medium size, very developed and harmonic skeleton, long shaped head, red and black colored mantel cit_bf(Petushi et al 2008)cit_af ref_bf(Petushi, 2008 ref_num286)ref_af.Peza goat is a medium size animal, developed harmonic skeleton, brown colored mantel, the presence of horns in 50% of animals, short horns, thin ears cit_bcit_af ref_bf(Hajno, 2007 ref_num288)ref_af. Çekini goat is a small size animal, brown colored mantel sometimes with white hair presence, developed skeleton, short neck cit_bf and Bulcar goat is a medium size animal, developed skeleton, short neck, red to black colored mantelcit_bfcit_af ref_bf(Hajno, 2008 ref_num287)ref_af. Peza, Cekini and Bulcar goat are located in central Albania (near Tirana and Gramsh). 

Traits and alleles

Seven different visible traits were considered. Presence or absence of reduced ears (EL). This trait is controlled by an autosomal locus with incomplete dominance.  The locus has two alleles El⁺ (wild) and El^R (reduced), (Lauvergne et al 1987).

Presence or absence of horn (Ho). The absence of horns is caused by the expression of a dominant allele (Ho^P), which is called polled allele, while the horns presence is caused by wild allele (Ho⁺), (Lauvergne et al 1987).

Presence or absence of wattles: Wattles are due to a dominant autosomal locus with variable expression (Machado et al 2000). The locus was named wattles (Wa) and has two alleles wattled (Wa^W) and wild Wa⁺), (Lauvergne et al 1987).

Presence or absence of beard (Br). Asdell and Smith (1928) have shown that this trait is controlled by an autosomal gene and depended on sex. The trait is dominant in males and recessive in females. The locus is named Br and has two allels: bearded (Br^b) and wild (Br⁺), (Lauvergne et al 1987).

 Presence or absence of long hair (Hl). This trait is due to the presence of an autosomal locus with incomplete penetrance (Rodero et al 1996). It is determined by hair length locus (Hl) wih two alleles long (Hl^L) and wild (Hl⁺), (Lauvergne et al 1987).

Presence or absence of roan color (Rn). the locus has two alleles Rn^R, roan which is dominant the wild allele (Rn⁺), (Lauvergne et al 1987).

Presence or absence of brown eumelanin (B). Brown eumelanin is a modification of black eumelanin due to an autosomal locus, which is probably recessive (Machado et al 2000, Oliveira et al 2006). The brown (B) locus has the alleles wild (B⁺) and brown (B^b).

Gene frequencies were calculated based on genotype frequencies, assuming that populations were on Hardy Weinberg equilibrium..  Nei genetic distance cit_bf(Nei 1972) cit_af ref_bf(Nei, 1972 ref_num290)ref_afwas calculated and used for the construction of NJ consensus tree cit_bf(Saitou and Nei 1987)cit_af ref_bf(Saitou, 1987 ref_num274)ref_af with Phylip package cit_bf(Felsenstein 1993)cit_af ref_bf(Felsenstein, 1993 ref_num284)ref_af. Bootstrap (1000 replicates) resampling was performed to test the robustness of the dendrogram topology. Nei genetic distance calculated from the allele data was plotted as principal component analysis (PCA)using GenAlEx program cit_bf(Peakall and Smouse 2006)cit_af ref_bf(Peakall, 2006 ref_num275)ref_af.  

Results and discussion

The allelic frequencies are estimated with the simple theory of panmixy cit_bf(Lauvergne et al 1987)cit_af ref_bf(Lauvergne, 1987 ref_num278)ref_af. In Table 1 are presented the allelic frequencies for each locus and each population separately and totally.

For the system El, allele E1⁺ had a high frequency. This allele is fixed in Bulçar, Çekin and Peza. It has a frequency of 0.759 and 0.992 in Hasi and Velipoja breed, respectively, displaying variability in Hasi goat. As a total population, the frequency of El+ is 0.95. Rodero et al 1992 found a frequency of 0.98 for this allele in populations of Blanca Serana breed. While, Oliveira et al 2006 found the frequencies of EL⁺ of  0,76 and 0,93 for  Ibimirim and Serra-Talhada rrespectively. Very high frequency of this allele is found in  goats of Ceará State (Brazil) and goats of the Mediterranean region Machado et al (2000) and goats of Tunisian oasis (Nafti et al 2009).  

The frequency of allele Ho⁺, for horn presence is very high in all breeds, higher than 0.9, showing that Albanian goat breeds have lost genetic variability regarding this allele. Rodero et al 1992 found also a very high frequency for both populations and in total for Blanca Serrana breed.  Similar results have obtained Oliveira et al 2006 for Ibimirim goats and. Nafti et al 2009 found lower frequency values for this allele. 

The most frequent allele for the presence/absence of wattles in Albanian goat populations is Wa⁺. In Çekin both alleles have equal frequency. The frequency of this allele in Albanian goat populations, is much lower than those observed in two goat populations of Pernambuco state (Oliveira et al 2006), in two Nigerian goat breeds (Yakubu et al 2010. Similiar allele frequencies are found in Blanca Serrana breed (Rodero et al 1992) and in goat of Tunisian oasis (Nafti et al 2009). The breeds display genetic variability regarding this locus.  

A high frequency of allele Br^b is observed in all breeds. This allele is fixed in Bulçar, Velipoja and Peza breeds. Rodero et al 1992, Macchado et al 2000, Oliveira et al 2006 and Nafti el 2009 observed variability in this locus.  

For the system HL, the most frequent allele is Hl⁺, which is fixed in Peza breed. High frequency of this allele is observed by Rodero et al 1992. But Oliveira et al 2006 found variability at this locus. 

The data provided here, display a variability in locus Rn, for all breeds, except of Velipoja, where allele Rn⁺ is fixed. 

For the system B, the frequency of allele B⁺ range from 0.031 to 0.340. Similar results have found Oliveira et al 2006. 

All populations were in HWE. Table 2 shows the expected heterozygosity values per each locus in each goat population. Heterozygosity values at population level ranged from 0.15 (Velipoja) to 0.26 (Çekin). Hasi is the population where polymorphism is found in all loci. Çekin is monomorphic only for locus El. Bulçar and Velipoja are monomorphic for two loci, and Peza is the population with the highest number of monomorphic loci. Hasi was the population with the highes level of polymorphism, but Peza displayed the lowest level of polymorphism.  

Genetic distances make it possible to evaluate the degree of genetic similarity between two populations. The shortest distance was between Velipoja and Peza (0.005). The highest distance is observed between Bulçar and çekin (0.054).The NJ tree revealed a cluster of Velipoja and Peza. The bootstrap values are higher than 50%, displaying a robustness of the NJ tree.

The principal component analysis (PCA) based on allele frequencies is presented in Figure 2. It is clear that Velipoja, Peza and çekin form one group. The first component clearly discriminate Hasi and Bulçar from the other breeds.

Goat farming is an important activity for the farmers in mountainous areas of Albania. In the present study are sampled more females. This is reflection of the structure of goat populations, since the farmers keep only one breeding male in their flock. The farmers are not keeping more breeding male because the consumers does not like their meat when they are slaughtered after finishing their role for breeding. In addition, the farmers every second year exchange the male with their neighbors to avoid inbreeding Management system is extensive or semi-extensive. The breeding program are absent for goat breeds. The mating is natural. In most of the cases there is only one male per flock that breed all the females in the flock. The lack of herd book, until nowadays, probably has facilitated the gene flow and the admixture of the breeds. This was an effort to characterize some important local goat breeds. In the future would be important to increase the number of traits examined and including also molecular markers.  

Conclusions

• Visible genetic profile of five local goat populations from Albania was defined based on Lauvergne criteria (1987). For some loci, El, Ho, Br, HL, all populations show low genetic variabilityThese loci are almost fixed in each population. Low value of expected heterozygosity are found.  Lack of herd book and of breeding programmes for a long time, till nowadays may have led to the homogeneity of these local breeds. Therefore it is extremely necessary to take appropriate measures to conserve gene pool and to start future livestock development programmes.

References

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Received 11 September 2011; Accepted 12 February 2012; Published 4 March 2012

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