الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Growth factors families include several genes such as myostatin and IGF-II that have the potential to influence economically important traits in beef cattle and so could be used as genetic markers for marker assisted selection (MAS). The objectives of the present study were to estimate the allele and genotype frequencies of the myostatin and IGF-II genes in the local breeds of cattle and buffalo in Egypt and to determine the effects of these polymorphisms on some growth traits in the studied breeds. Genomic DNA was extracted from whole blood of 180 animals including Baladi, Holstein cattle and Egyptian buffalo. The PCR products of investigated genes were subjected to genotyping. PCR-SSCP technique was used to genotype myostatin gene at the three coding exons. While the second exon was monomorphic, five genotypes were determined for the first exon (AA, AB, AC, BC and AD) and three genotypes for the third exon (AA, AB and BB). Significant positive associations were found between exon 1 genotype AD in Holstein and AB in Baladi cattle with the average daily gain. For exon 3, the AB genotype showed positive effect on the average daily gain in both Holstein and Egyptian buffalo. RFLP-BsrI analysis was applied to genotype animals at the 292C>T SNP in IGF-II exon 2. Three genotypes, CC, CT and TT, were detected with a significant association between the CT genotype and weaning weight in Holstein cattle. These results could be included into marker assisted selection programs to improve the productivity in these local breeds.