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Jordan University of Science and Technology (JUST) 2013

The Relationship Between Some Ovine Genes and some Economical Traits in Awassi sheep

ALA’A ADNAN ALI ALQAISI

Titre : The Relationship Between Some Ovine Genes and some Economical Traits in Awassi sheep

Auteur : ALA’A ADNAN ALI ALQAISI

Université de soutenance : Jordan University of Science and Technology (JUST)

Grade : Master of Science (MS) 2013

Présentation
Recently, gene markers have been widely used in animal breeding programs. In sheep, the generation interval is considered to be long ; genetic markers can help in reducing the interval in term of genetic selection, so instead of waiting for 3-4 years for making the selection decision, it’s possible to select the animals early depending on gene marker results (genotyping) at one day old lambs. Therefore, two trials were conducted at Al-Khanasry Research Station (National Center for Agriculture Research and Extension (NCARE)), in order to investigate the relationship between some genes variants and some economical traits in Awassi sheep.
The first trial, at the beginning of lambing season of 2011/2012 ; the available rams lambs were genotyped using RFLP technique at age of two weeks for the ovine calpastatin gene (CAST), then fattening period was conducted using 10 ram lamb/ MspI - of CAST genotypes (MM (homozygous) and MN (heterozygous) (5 lambs from each genotype). Individual pens were used for growth monitoring and a standard ration was used for the two group genotypes. All lambs weighed at biweekly intervals, feed intake measured in daily bases, and all animals from each genotype slaughtered at the end of fattening period for the purpose of carcass and meat quality evaluation. The statistical results showed a significant differences between CAST genotypes in growth performance (growth rate and final body weight).Animals with MN genotype showed higher average daily gain and final body weight than animals of MM genotype. CAST gene genotypes observed to have a significant effect on some carcass component and meat quality. MN genotype showed lower total bone and higher meat to bone ratio than MM genotype in dissected leg cut, and MN genotype had higher Longissimus muscle weight than MM animals.Meat quality analysis showed that animals of MN genotype had higher shear force and lower cocking loss and lightness therefore CAST gene can be considered as one of the major genes that controlled some meat quality traits.
The second trial ; all lambing information’s were retrieved from the available recodes for the available animals (208 ewes and 27 rams). Information’s included ; lambing season, parity, type of birth, dam weight at lambing and sex of lambs and prolificacy. Blood samples were collected, then Restricted Fragment Length Polymorphism (RFLP) technique was used for genotyping process for the following genes ; Growth Differentiation Factor 9 (GDF9) (exon 1), fecundity gene (FecB), Prolactin (PRL), and insulin like growth factor binding protein (IGFBP). Allelic and genotypic frequencies of GDF9 were 0.951 for M allele (mutant allele) and 0.049 for N allele. Genotypic frequencies were : 0.889 for MM genotype, 0.12 for MN genotype and 0.00 for NN genotype in GDF9 gene ; the allelic frequencies of PRL gene were 0.757 for A allele, 0.243 for B allele, while the genotypic frequencies were 0.646 for AA genotype, 0.221 for AB genotype and 0.131 for BB genotype. FecB gene found to be monomorphic in our population. Prolificacy was investigated in the studied genes genotypes (GDF9, FecB and PRL), in the statistical Model we include included Lambing season, Parity Dam weight at Lambing in addition to the studied genes genotypes, and the analysis was performed using SAS (2004).The total number of records that used in the analysis was 355 records. The wild type genotype of FecB gene was only detected (all individuals were homogeneous for this gene) while non-significant differences was observed between GDF9 gene genotypes was detected in prolificacy. Prolactin gene genotypes observed to have a significant effect on prolificacy, BB genotype had 0.16 and 0.11 higher prolificacy than AA and AB genotypes, respectively. It could be concluded that PRL gene has a strong relationship with prolificacy and could be used as Marker gene that can be used for improving prolificacy rate in Awassi sheep, while FecB and GDF9 are not responsible for the higher prolificacy that could be observed in Awassi sheep

Mots clés : Gene markers, calpastatin gene, Growth Differentiation Factor 9 gene, fecundity gene, Prolactin gene, insulin like growth factor binding protein gene, Awassi sheep polymorphism.

Présentation

Page publiée le 18 octobre 2016, mise à jour le 14 juin 2018