Phenotypic characterization and growth performance of sheep populations in Northeastern Algeria

LAIDI, Ziane and DEGHNOUCHE, Kahramane and TITAOUINE, Mohamed and MEZIANE, Toufik and MAMMERI, Adel and GHRISSI, Djellal (2023) Phenotypic characterization and growth performance of sheep populations in Northeastern Algeria. Doctoral thesis, Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie.

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Abstract

The presente study aims to characterize the sheep population phenotypically in Northeastern Algeria, to determine the growth dynamic and performance of pre-weaned lambs of this area and to assess the altitude effect on the growth performance. For this purpose, three experiments were performed. The first experiment was carried out in eight farms, in which a total of 160 ewes were subject to 4 quantitative body measurements (body length, withers height, tail length and wool weight) and 9 qualitative traits (head length, ear orientation, horn presence, neck length, wool extent, tail texture, eyes shape, head color and wool color). The results indicate that the sheep population in these areas belonged to the Ouled Djellal sheep breed with some atypic phenotypes, which refers to uncontrolled crossbreeding. Body measurements show moderate variation coefficient values. Clear correlations were revealed between withers height and tail length (0.30) and body length and wool weight (0.26). The Hierarchical Agglomerative Clustering analysis sub-divided the sheep population into three classes. The second experiment was conducted on two institutional farms, ITDAS and ITELV, in which 50 adult animals were the subject of 15 body measurements: withers height, back high, rump high, chest depth, head length, head width, ear length, ear width, chest width, rump width, body length, heart girth, cannon circumference, tail length and tail circumference. The results reveal that the studied sheep of the Ouled Djellal breed is a morphologically homogeneous population with superiority, in almost body measurements, for males. The correlation coefficients show that body weight can be estimated by heart girth alone or combined with other body measurements such as tail circumference, withers height, head length and cannon circumference. The third experiment evaluated the growth dynamics and the effect of altitude on different growth phases of pre-weaned Ouled Djellal lambs. Seven sites were chosen for this study. A total of 49 lambs were weighed. Their average daily gain was calculated at different ages (birth, D 30, 60, 90 and 120). The results show that maximum growth occurs during the lamb’s first month of life at 200 g/day. Highly positive and significant correlations were recorded between D 90 and D 120 (0.94), D 60 and D 120 (0.88), D 60 and D 90 (0.87) and D 30 and D 90 (0.77). Concerning the altitude effect, lambs born in low altitude regions show a better growth performance than lambs born in high altitude regions which confirms that the Ouled Djellal breed is a typical breed of the steppe and the high plains

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