الفهرس 
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Abstract
A total number of 110 samples were collected, each sample weighted 250 g from different cuts_ Fore quarter (Shoulder-Chuck) and Hind quarter (Silver Side- Knuckle) of ( frozen Brazilian beef meat) and ( frozen Indian beef meat). Samples were subjected to macroscopic examination searching for the macroscopic forms of cyst, Pepsin digestion to obtain digestion fluid contain free parasites, histopathology examination was performed on paraffin- embedded sections (5μm) stained with hematoxyline and eosin (H and E) stain, and molecular identification. Isolated macrocyst and tissue samples preserved in 70% ethanol, genomic DNA was extracted for each sample by the phenol/cholorform method following digestion by Proteinase K and Lysis buffer, PCR was done for amplification of partial sequence of small subunit ribosomal RNA (18S rRNA) gene. Those variable regions have shown to be suitable genetic markers for distinguishing Sarcocystis spp. PCR was done by using Primer (1) amplifying a fragment of approx. 900 bp., the used primer combination ( 18S9L & 18S1H) is Sarcocystis genus-specific and does not amplify host DNA, and (primer 2) which was specific for 18S rRNA sequence of S. fusiformis, to amplify the DNA extracted from tissue sample and macroscopic cyst . DNA Sequencing was performed for (8) Samples, represent samples of macroscopic cyst and tissue samples . The PCR products were sent to macroGene company (South Korea) to sequence in one direction (Forword) using ABI 3730XL DNA sequencer ( Genetic Analyser, Applied Biosystem, Hitachi, Japan). The parasitic infection rate of Indian buffalo meat was positive infection for both macroscopic and/or microscopic Sarcocystis spp., While negative infection for Toxoplasma gondii and Cysticercus bovis . In Brazilian beef meat, parasitic examination revealed that the infection rate was negative for Sarcocystis spp. , Toxoplasma gondii and Cysticercus bovis. The percentage of positive samples of Sarcocystis spp. in Frozen Indian buffalo meat by macroscopic examination was 23.6% and by histo-pathologically was 20% while by convential PCR was 70,9% infection with both macroscopic and/or microscopic Sarcocystis spp. The percentage variation of Sarcocystis spp. in Frozen Indian buffalo meat which infected by macroscopic cyst only or microscopic cyst only or both of them as mixed infection , where the higher rate of macrocyst infection was in Silver Side 18.8% ,then Shoulder and Chuck are the same 12.5% but Knuckle was 0% ,also the higher rate of microcyst infection was in Silver Side 18.8% , then Shoulder and Knuckle are the same 6.25% but Chuck was 0% ,while in mixed infection, Shoulder, Chuck and Knuckle are the same 12.5% but Silver Side was 0% . Macrocysts that isolated from Frozen Indian buffalo meat were typically fusiform in shape (Wide in middle and tapered ends), microcysts that stained by H and E were eosinophilic as the sarcocyst had blue color in muscle tissue , they have been detected from muscle tissue which stained red color. PCR was done by (primer 1) yielded an amplicon of approximate length of (900bp.) as positive results for Sarcocystis spp. macroscopic and/or microscopic. PCR was done by (primer 2) yielded an amplicon of approximate length of (270 bp.) as positive results for Sarcocystis spp. ( Macroscopic) only. The results of DNA sequencing of 18S rRNA gene and phylogenic tree analysis revealed that infection of frozen Indian buffalo meat with S. fusiformis strains accession no.(JQ713824.1 and KR186132.1), Moreover, the results of DNA sequencing of 18S rRNA gene revealed that infection of frozen Indian buffalo meat with S.cruzi strain accession No.(AF017120.1). Two of the most pathogenic species of Sarcocystis are S. cruzi and S. tenella. These species form microscopic cysts in their intermediate host, and both have canines as the definitive host.