Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Zoology

Ruminant milk production and composition are influenced by genetic and non genetic factors. Caseins show high quantitative and qualitative variability in goat milk due to structural polymorphisms. Also, diacylglecerol acyltransferase (DGAT) genes have essential role in biosynthesis of triglyceride in goat milk. This study aimed to investigate the effect of time of lactation, parity number and does live weight, as well as, Üs1-casein gene (CSN1S1), Üs2-casein gene CSN1S2 and Diacylglecerol acyltransferase1 gene (DGAT1) polymorphism on milk quantity and quality of Zaraibi goat. Milk components were estimated by infra-red spectroscopy. Moreover, restriction fragment length Polymorphism (RFLP) method was used to detect genetic polymorphism in CSN1S1, CSN1S2 and DGAT1 genes, while allele specific polymerase chain reaction (AS-PCR) was used to distinguish between alleles A and 0, as well as, identifying both B and E alleles in CSN1S1 locus. To determine the mutations in nucleotide sequences of the amplified fragments of CSN1S1 and DGAT1 genes sequencing technique was used. Daily milk yield were significantly affected by lactation time, parity numbers and does live weight. Milk yield peaked at the 2nd week from kidding and tended to decrease until the end of lactation. Moreover, milk yield increased with the increase of the parity number and does live weight. Levels of milk fat, protein, lactose and total solid were significantly affected by lactation time

Issued also as CD