Identification of genes associated with economic traits in livestock

Two Egyptian goat breeds, Zaraibi (n=2l) and Barki (n=24) and two Italian breeds, Nicastrese (n=24) and Aspromonte (n=8) were used to investigate the genetic structure of the casein genes in some Egyptian and Italian breeds, evaluate the genetic variability at the alpha S 1Æ( casein (CSN1Sl) in these breeds and study the relationships among and within the Egyptian and Italian goat breeds. PCR (polymerase Chain Reaction and RFLP (Restriction Fragments Length Polymorphisms) methods were used to identify CSNIS1 alleles A, B, E, F, N and 01. The genotypes AB and BB were the most frequent (0.163) in the Egyptian breeds. CSN1Sl showed high frequency of strong alleles, A and B, in the Egyptian breeds CSNISI strong alleles were represented by about 61% of total number of alleles in Barki and about 69% in Zaraibi. CSNIS1-Ol allele has been detected only in Barki with low frequency (0.045). Genetic differentiation(Fst)showed similarity between Egyptian breeds. Low genetic distance was observed between the Egyptian breeds and between the Italian breeds. For identifying different alleles in the CSNI S2 locus, PCR and NcoI endonuclease RFLP was used to analyze Egyptian and Italian breeds. Barki, Zaraibi and Aspromonte breeds carry one of the alleles CSNI S2-A, B, C, F or E which associated with normal casein S2 protein in milk. The null allele CSN1S2-0 was not observed in Egyptian breeds CSNI S2-0 allele was observed with low frequency in Nicastrese. In beta casein, PCR was held to identify CSN2-A allele and CSN2-0. There was no polymorphism found at CSN2 locus in Barki and Zaraibi. The Egyptian breeds carried only the CSN2-A allele. Allele CSN2-01 was in low frequency in Nicastrese (0.04) and in a frequency of 0.19 in Aspromonte. In kappa casein, genotype CSN3B/B appeared in all the tested animals. No new polymorphism was found in CSN3 in the Egyptian breeds. Results indicate that Egyptian breeds have a considerable genetic profile with high variability carrying the favorable casein alleles in high frequency. That makes Egyptian goats potential animals for milk and subsequently for cheese production. Genotyping of the casein genes will help in selecting females and males in early stages for milk production . Genotyping of the casein genes will help in selecting animals from both sexes in early stages for milk production, Using this strategy will reduce time and efforts in establishing breeding program for Egyptian breeds. Selection for strong alleles CSNlSl-A and CSNISl-B and alleles associated with normal alpha S2, beta and kappa caseins and against low and null alleles is recommended when developing breeding programs for Egyptian goats.