University of Khartoum

Molecular Genetics and Phenotypic Characterization of Some Beef Quality Traits in Baggara Cattle

Molecular Genetics and Phenotypic Characterization of Some Beef Quality Traits in Baggara Cattle

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Title: Molecular Genetics and Phenotypic Characterization of Some Beef Quality Traits in Baggara Cattle
Author: Omer, Romaz Mohammed Ahmed
Abstract: The objectives of the present study were to estimate the allele and genotype frequencies of single nucleotide polymorphisms (SNP) of the growth hormone1 (GH) locus, the Insulin-Like Growth Factor Gene (IGF1) and the Leptin gene (Lep) and to test the association between genotypes and meat quality traits of two subtypes of Baggara cattle (Nialawy and Messeiri). Sequencing and sequence analysis of the target regions were carried out. The present investigation was carried out on 130 Baggara bulls of 4-5 years average age, divided into two groups according to sub-type; 65 Nyalawi and 65 Mesairi. They were finished in the traditional feedlot system and slaughtered in Ganawa abattoir in Omdurman locality, Khartoum state. Slaughter weight, carcass weight and dressing percentage were determined. One hundred and thirty meat samples were cut from the Longissmus dorsi thoracis muscles within 1hour post-slaughter for analysis of some meat quality traits using standard methods. One hundred and thirty blood samples from jugular vein (3-5 ml) from each bull were collected in EDTA tubes for DNA extraction using guanidine chloride protocol, analysis involved PCR-RFLP and sequencing. Statistical analysis was done using ANOVA, Chi-square, Bio-Eedit and MEGA programs for sequence analysis and estimating genetic distances. The results revealed a significant difference between the two subtypes in live weight, hot carcass weight, dressing percentage, myofibril fragmentation index(MFI),water holding capacity(WHC), cooking loss , fat percentage, moisture, and ash content. There was a high genetic similarity in SNP at position 2141C>G of growth hormone 1 gene (GH1) in exon 5.There were insignificant (P>0.05) differences between the two breed subtypes in SNP C>T at position -472 in the 5-noncoding region of the IGF-1 gene upstream from the ATG codon. However, the frequencies of mutant homozygotes (TT) were very low and existed only in the Mesairi subtype and the heterozygote (CT) genotype existed in the two subtypes. The associations between IGF1 genotypes and the meat quality traits were not significant(P>0.05). The analysis of variance showed that differences between IGF1 genotypes in all traits studied were not significant except in fat content (significant, P<0.05). Breed x IGF1 genotypes interactions were not significant (P>0.05) except in MFI which was close to significance (P=0.079). There was a significant (P>0.05) associations in SNP C>T of the leptin gene between breed subtypes, carcass weight, dressing and fat percentages. The association with MFI was close to significance (P=0.072) and the association with live weight, WHC, cooking loss and meat chemical composition were not significant (P>0.05). Leptin genotypes effects on WHC were significant (P<0.05) but were not significant on the remaining traits. Leptin genotypes interactions with breeds were not significant (P>0.05). The study recommended the use of molecular markers will offer a great potential to improve efficiency of animal breeding for meat quality traits. The effect of the mutations in exon five of GH1, 5- flanking region of IGF1 and exon 2 in the leptin gene should be investigated in all subtypes of Sudanese Baggara cattle while also evaluating their interactions with other functional SNPs. Further research in other regions of the sequence of these genes and other candidate genes affecting meat quality traits is also recommended.
URI: http://khartoumspace.uofk.edu/123456789/25553


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