Abstract

As part of the study of the biodiversity of animal genetic resources in sheep, our study is based on genetic studies of Algerian sheep breeds. The genotypic determinism of population presupposes the prior knowledge of its phenotypic characterization and its performances. For this purpose, the zootechnical approach addresses firstly the phenotype to better characterize these breeds by the use of body measurements and zootechnical indexes (for 430 animals of Ouled Djellal, Rembi, Hamra, Berbere and Barbarine breeds) and secondly the production performance by estimation of live weight in 81 animals (case of the Ouled Djellal breed) and the study of ADG (Average Daily Gain) in 105 lambs. The genetic study is based on the determination of the polymorphism at the gene PRNP (scrapie) from 213 samples of eight sheep breeds. The morphometric characterization revealed a clear superiority of the Ouled Djellal breed for all the traits studied. While the study of phenotypic characteristics shows low genetic diversity and the majority of the population is white except for Hamra. For the performances studied, the live weight can be estimated by a simple linear measurement, the chest girth is the best measure to estimate the weight, which was confirmed by the formula BW=57.9*HG3. In addition, the control of ADG indicates a low dairy productivity which is related to mortality rate and livestock management. The study of PRNP polymorphism in eight sheep breeds (Ouled Djellal, Hamra, Rembi, Berbere, Barbarine, Tazegzawt, Taadmit and Sidaou) using 213 samples showed the presence of high frequencies of the haplotypes associated with scrapie resistance such as ARQ, AR143RQ and ARQK176. The VRQ haplotype, associated with higher susceptibility to scrapie, was absent in all Algerian breeds studied. In addition, new PRNP polymorphisms N103K, M137I, I142M are described for the first time in sheep. These breeds have a considerable genetic variability in codons other than those linked to scrapie susceptibility. The phylogenetic tree and Cluster analysis defined a similarity genetic between Ouled Djellal and Taadmit, between Rembi and Berbere and finally between the Hamra and Sidaou breeds. These results were analyzed and discussed.
Keywords:
Characterization – Phenotype – Genotype – Pathology – Breed – Sheep – Algeria

Information

Item Type:	Thesis
Divisions:	» Production animales, biotechnologie et sante
ePrint ID:	1399
Date Deposited:	2018-10-08
Further Information:	Google Scholar
URI:	https://www.univ-soukahras.dz/en/publication/article/1399

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