DNA isolation and PCR amplification
The precision and concentration of the DNA used as a template in the PCR procedure affected its success. The purity and concentration of the DNA ranged from 372.6 to 764.6 with the degree of purity reached from 1.8 to 1.96 μg/mL. The result of electrophoresis on a 1.5% agarose gel showed succesfully DNA amplification (Fig 2 and 3), generating a COI gene composing of 700 bp.
mtDNA sequence variation and genetic diversity
Considering result of alignment 770 nt COI gene, the base content of thymine (T) were 28.86%, cytocine (C) 26.78%, adenine (A) 27.38% and guanine (G) 16.99%. Total nucleotide A+T were 56.24% and G+C were 43.77%, therefore GC<AT. Multiple alignments obtained SNP (single nucleotide polymorphism) were 962 sites consist of 618 transition, 179 transvertion, 158 insertion and 7 deletion. Based on the polymorphic sites Bali cattle dominated among the purebred were found 56 situs, PO 33 and Madura cattle 8 sites. Among the crossbred (CB) cattle, the highest number of SNP found in (Angus×PO) were 139 sites, (Bali- Limousine-Brahman) 81 sites and (PO´Brahman) 72 sites (Fig 4). In addition, data obtained that specific nucleotide COI gene was 53.89% (415/770) conserved nucleotide and 42.2% (325/770) variable nucleotide. Variable nucleotide consist of 15.97% (123/770) parsimony informative and 22.7% (176/770) singlet on nucleotide.
The observed polymorphism number of SNP transition C>T in purebreed cattle (Bali, PO) and CB (Simmental-Bali), (Angus-PO), (Limousine-PO) were higher than T>C, A>G and G>A. Transvertion SNP A>T in (Angus-PO) cattle higher than another breed. Number of insertion detected in CB (Angus-PO), (Bali-Limousine-Brahman) and (Bali-Limousine-Limousine) more than another breed. The heterozygosity of Bali cattle, (Angus-PO), (Simmental-Bali), (Bali-Limousine-Brahman) and (Bali-Limousine-Limousine) were high, which means that cattle above have plenty of diversity of genetic
(Kumar et al., 2017a; Pundir et al., 2019).
The COI sequence analysis identified in Bali cattle dominant number a non-synonymous mutation among purebred cattle. Transition (C>T) at position 485, 500 and 631 of the translated sequence, resulting in an amino acid change serin to leusin. SNP C>T at 503, 533 resulting threonine change to isoleusin, at position 516, 539, 622 resulting prolin change to leusin. In addition, non-synonymous mutations in CB cattle are most commonly found in (Simmental-Bali), (Bali-Limousine-Limousine) and (Bali-Limousine-Brahman). Transition (C>T) at position 485, 500 and 631 of the translated sequence, resulting in an amino acid change serin to leusin found in CB (Simmental-Bali), (Bali-Limousine-Brahman), while in (Bali-Limousine-Limousine) found at 596. Transition (C>T) at base position 476 and 516 resulting amino acid prolin change to leusin in CB (Simmental-Bali) and (Bali-Limousine-Limousine) while at position 622 that
missense mutation found in (Simmental-Bali) and (Bali-Limousine-Brahman). Some sites of the position of the asinonymal mutation in CB are the same as those found in Balinese cattle, so that base positions of CB above have the potential to be used as markers.
Genetic distance and phylogenetic tree based on the COI gene
Results of the analysis of genetic distance between purebreed, CB cattle and
B. taurus was in the range of 0.000 to 0.297. The result was in accordance with
Kumar et al., (2017b) who stated that the genetic diversity of COI gene in the Bovidae was between 0.0 and 1.92%. In this study showed that seven purebreed cattle might be grouped into
B.taurus because it had a genetic distance of 0.000 (Angus, Brahman and Simmental), while Limousine has a genetic distance of 0.002 and Madura with a value of 0.013. Bali and PO cattle have a longer genetic distance were 0.055 and 0.095. Among the CB (Angus-PO) is very far to the GenBank reference (0.248) and other CB and purebred. The closest genetic distance of CB (Bali-Brahman) and (Bali-Madura) is 0.077 each. We revealed that most of CB cattle should be grouped into
B. indicus (Bali and PO) because it had a genetic distance closer than to
B. taurus.
A Neighbor-joining (NJ) tree was generated in order to verify the phylogenetic relationship of 20 of the COI gene using MEGA 11 based on nucleotide diversity (Fig 5). The result showed that all these samples were grouped into three main clades (A, B and C) and outgroup (D). Clade A is consist of CB cattle (Angus-PO) with boostrap 94%. CB cattle (Angus-PO) which separated from other groups of CB cattle.
B clade was supported by 100% bootstrap value and consist purebreed cattle Angus, Brahman and Simmental with the closest genetic distance was 0.00 and 100% homolog to
B. taurus, while Limousine has a genetic distance of 0.002 and Madura with a value of 0.013. Cluster C has a boostrap value of 48%, the members of this cluster are mostly CB cattle except PO and Bali. The genetic distance of PO and Balinese cows is 0.055 and 0.095, respectively. Considering the result, based on the DNA barcode, most of CB cattle were in the same cluster with
B. indicus as well as Bali and PO cattle.
Statistical analysis
The result of Pearson’s corrrelation analylsis could be shown on Table 2 and Table 3.
Results of Pearson’s correlation analysis that was illustrated in Table 2 showed that there was a very significant (p-value <0.01) and significant (p-value <0.05) correlation between SNP (nucleotide) and several hematological parameters. These hematological parameters were WBC, RBC, HCT, MCH and MCHC. Three parameters had a very significant correlation to SNP, namely RBC (0.003), HCT (0.005) and MCHC (0.005). Other parameters had a significant correlation to SNP were WBC (0.017) and MCH (0.017). Whereas Pearson’s correlation analysis results in the following Table 3 described that several hematological parameters had a very significant correlation to SNP (amino acid). These parameters were RBC (0.001), HGB (0.006) and HCT (0.001).
Other parameters had a significant correlation to SNP were WBC (0.033) and MCHC (0.032). Only albumin (0.013) as a blood chemistry parameter had a significant correlation to SNP (amino acid). These hematological and blood chemistry parameters that had a very significant and significant correlation to SNP (nucleotide and amino acid) would be used as a dependent variable to construct multidimensional scaling (MDS) map. The results of multidimensional scaling map would be illustrated in the following figures.
Fig 6 above shows that all samples were divided into three groups. Angus-PO CB (SpB) was localized separately (A). The second group members were purebred (B). The last group members were crossbred (C), except S1 (Ongole) was purebred. Results of the MDS map (Fig 6) shows that each group has mostly the same members configuration as the phylogenetic tree groups.
Fig 7 above described that the MDS map configuration based on the Amino Acid correlation to hematological and blood chemistry parameters was mostly the same as the MDS map based on the Nucleotide correlation to both variables (Fig 7), so both MDS maps had similar configuration members as the phylogenetic tree for describing the relationship among samples.
MDS map method could be an appropriate technique to support and complete Neighbor-joining for constructing the phylogenetic tree.