ORBi: Hammami Hedi - Sustainable dairy farming - A case study of Holsteins in a developed and an emerging country

Reference : Sustainable dairy farming - A case study of Holsteins in a developed and an emerging cou...


	Document type :	Scientific congresses and symposiums : Unpublished conference
	Discipline(s) :	Life sciences : Genetics & genetic processes Life sciences : Animal production & animal husbandry
	To cite this reference:	http://hdl.handle.net/2268/25845

Title :	Sustainable dairy farming - A case study of Holsteins in a developed and an emerging country
Language :	English
Author, co-author :	Hammami, Hedi [Université de Liège - ULg > Gembloux Agro-Bio Tech > Gembloux Agro-Bio Tech >]
	Rekik, Boulbaba [Ecole Supérieure d'Agriculture de Mateur > Productions animales > > >]
	Bormann, Jeanne [Administration des Services Techniques de l'Agriculture, Luxembourg > > > >]
	Stoll, Jean [Convis Herbuch Service Elevage et Génétique > R&D > > >]
	Gengler, Nicolas [Université de Liège - ULg > Gembloux Agro-Bio Tech > Gembloux Agro-Bio Tech >]
Publication date :	23-Sep-2009
On invitation :	No
Audience :	International
Event name :	IDF World Dairy Summit 2009
Event date :	20-24 septembre 2009
Event organizer :	GERMAN NATIONAL COMMITTEE
Event place (city) :	Berlin
Event country :	Allemagne
Abstract :	[en] Sustainability of breeding programs under the flow of exchange among various environments are conditioned by the ability of genotypes to adjust sufficiently their phenotypes in response to changes in their new bio-physical conditions, and also by the capabilities of farmers to balance between environmental, ethical, social. and economic aspects. The objective of this paper was to quantify the effectiveness of genetic responses from indirect selection in high- and low- to medium- input systems using Luxembourg and Tunisian Hoisteins. The magnitude of genotype-by-environment interaction (GxE) for production traits was firstly investigated based on the country border delimitation as environmental character state. Secondly, three herd management levels reflecting feeding and management intensity were identified in each country and GxE was investigated within and across country environments. Significant GxE was detected for milk yield and persistency with large differences in genetic and permanent environmental variances between the 2 countries. Genetic correlations for 305-d milk yield and persistency between Luxembourg and Tunisia were 0.60 and 0.36. Low rank correlations obtained between estimated breeding values of common sires translated a significant re-ranking between the 2 countries. Within-country environments analysis show that the magnitude of GxE varied from only scaling effects resulting from heterogeneous variances in high-input systems to considerable re-ranking of common sires under limited feeding resources, low management care, and stressful conditions in low-input systems. Overall, this study shows that substantial differences exist between Hoisteins in terms of their sensitivity to production environ ment suspecting the sustainability of the dairying system. In high-input systems, GxE effects are expected to be easily managed but harmful effects of intensive dairy systems should be considered. Selection of breeds under less intensive production systems respecting the ruminant's specificities should be encouraged. In law-input systems, selection for adaptive traits under their specifie conditions and improvement of management conditions and husbandry practices are needed.
Target :	Researchers ; Professionals
Permalink :	http://hdl.handle.net/2268/25845

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