Thesis (M.Sc.) - Cairo University - Faculty of Veterinary medicine - Department of Biochemistry and Chemistry of Nutrition

Abstract: There are several immune genes which are responsible for susceptibility of cattle to mastitis. The objectives of the present study are to estimate the effect of the polymorphism of two of those genes, Forebrain embryonic zinc finger-like (FEZL) and Insulin-like growth factor 1 receptor (IGF1R), to determine their value in marker assisted selection (MAS) regarding mastitis resistance in Holstein-Friesian breed in Egypt. A total number of 112 whole blood and milk samples were collected from Holstein-Friesian lactating cattle. Genomic DNA was extracted from whole blood and used for detection of genetic polymorphism in FEZL and IGF1R genes by single strand conformational polymorphism (SSCP) technique. RNA was extracted from milk and used for determination of level of expression of FEZL and semaphorine5A (SEMA5A). The obtained results of the present study revealed the presence of single nucleotide polymorphism (SNP) in glycine stretch of FEZL and in cytosine stretch of IGF1R in correlation with somatic cell count (SCC). The resulted SNP was further confirmed by sequencing of the PCR product. Moreover, mastitis and high somatic cell count reveals an increase in level of expression of FEZL and SEMA5A. These results could be included into MAS programs to improve the breeding selection in lactating cattle.

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