Özet:

Bovine mastitis is an infectious disease of the mammary glands of dairy cows. It has a high incidence in cows worldwide. It is usually caused by bacteria entering the nipple tube and spreading to the breast tissue. In recent years, molecular diagnostic technology has become the gold standard for diagnosing mastitis. They provide qualitative, quantitative, and large-scale rapid diagnosis. Its diagnostic function can identify infections at the subspecies level, which is essential for epidemiological investigations. They are increasingly used in the management of mastitis to identify vaccine candidates and select dairy cow breeds that are resistant to mastitis.The present study revealed that Staphylococcus aureus had the most significant relative prevalence, followed by Escherichia (15 percent), Streptococci (12 percent), Pseudomonas (10 percent), Klebsiella (7 percent), and Bacillus (5 percent).Furthermore, results of this current research identified a total of 02 mutations in the gap gene of Staphylococcus aureus, 01 mutations in T13 samples of Tehri and 01 mutation in G13 samples of Gambat through the use of PCR gel electrophoresis and DNA sequencing techniques under three different environments of district Khairpur namely Tehri, Gambat and Khairpur. According to the genetic code, these mutations are classified as missense mutations because they alter the codons and their final amino acids. Furthermore, our results revealed the substitution of TTC codon at bp 79 that was changed into TTA codon, where the former one was coding for Phenylalanine amino acid, which is classified as neutral and nonpolar due to the inert and hydrophobic nature of the benzyl side chain, and the changed codon codes for Leucine amino acid, which is also an essential amino acid. Whereas the second nucleotide change was found at 35bp of the Gap gene, where the TGT codon was converted into TGG, the primary codon was coding for Cysteine amino acid, which is a semi-essential amino acid with a thiol side chain that frequently participates in enzymatic reactions as a nucleophile, which was changed into Glutamic acid, which is also a non-essential amino acid which is an excitatory neurotransmitter with one more methylene group in its side chain than aspartic acid. In contrast, no mutation was found in the other samples included in our investigation. Our findings show that Staphylococcus is highly adapted to the TEHRI environment, as indicated by identifying required amino acids in the acquired sequence but not the GAMBAT environment. Our findings can be used as a reference and guide for selecting extremely diversified and well-adapted bacteria environments that cause mastitis in cattle.

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