الفهرس 
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Abstract
The improvement of reproductive traits in livestock has become of increasing interest. Sheep is the perfect modal for studying the variation in quantitative traits as (ovulation rate and litter size) among different breeds. Because of low heritability of these traits so traditional methods of selection for improving of these traits are not effective and had been limited. Recently, improvement in molecular genetics provided the major genes associated with reproduction that can be introduced in breeding through marker assisted selection (MAS).
Due to the importance of genotyping of economic genes in the Egyptian local sheep breeds, the present study aimed to find out polymorphism patterns of the Egyptian sheep fecundity genes ( BMP1B receptor, BMP15, GDF9) as a tool for genetic improvement of ovulation rate and twinning traits in Egyptian sheep.
Blood samples were collected from 115 animals from two different regions, these animals have reproductive records and belonging to three breeds of Egyptian sheep; Barki, Rahmani and Ossimi. According to the records animals were classified into two groups (high prolific, in which mothers gave more twin births than single one) and (low prolific, where more single births than twins). Also all of these animals were categorized into three groups (carrying single, twine fetuses or non-pregnant) prior to blood sampling through a trans-abdominal ultra sonography. Genomic DNA was extracted from the whole blood and prepared for PCR application. The specific primers were designed for three genes related to ovulation; Bone morphogenetic protein type 1B receptor (Booroola gene), Bone morphogenetic protein 15 and Growth differentiation factor 9 gene. PCR products were visualized on agarose gel. For genotyping two techniques
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Summary and Conclusion
were used in this study; PCR-RFLP and ARMS (amplification refractory mutation system) then sequence analysis.
The PCR products of the two genes (BMP1B and BMP15) were digested with Avaǀ ǀ and Hinfǀ endonucleases respectively. While the GDF9 gene is amplified using ARMS-PCR technique which detect the wild and mutant types in the same reaction. After that the products of the BMP15 and GDF9 gene were undergone to DNA sequencing for determination of the single nucleotide polymorphism. The results showed that:-
BMP1B gene
The PCR-RFLP technique was used to study the polymorphism of BMP1B gene. The PCR amplified a fragment with 190-bp and 140-bp in size and the RFLP digestion with Ava11 endonuclease, showed that all tested sheep possess homozygous genotypes, named AA and BB.
BMP15 gene
A 356-bp product of BMP15 gene was amplified by PCR. Then it was digested with Hinf1 restriction enzyme. Results showed that all studied sheep possess homozygous genotype as CC. The sequence analysis showed there is no any polymorphism in studied sheep breeds
GDF9 gene
The ARMS-PCR technique was used to study the polymorphism of FecG gene. The PCR amplified a fragment with 187 and 343-bp in size and the results showed that there are no genetic polymorphism in the Egyptian sheep. The sequence analysis showed there is no SNPs on the level of 343 and 187 bp band of Fec G gene in Egyptian sheep.
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Summary and Conclusion
In conclusion
BMP1B, BMP15 and GDF9 genes are monomorphic which means that there is genetic conservation of those genes in Egyptian sheep breeds. Further researches should be done using large number of samples from sheep breeds using different genetic techniques. So the genetic factors
affecting fecundity should be investigated further by other
candidate loci in Egyptian sheep.
Recomendations
Absence of mutation in Egyptian sheep breeds could be explained the low litter size for these breeds.
More screening is required for discovered new mutations with increasing animal numbers.
The absence of prolificacy genotypes in our sheep breeds implies that these mutations affecting prolificacy may be added to our breeds by genetic introgression which allows the introduction of a desirable genotype in Egyptian breed.