Reference : Sustainable dairy farming - A case study of Holsteins in a developed and an emerging ...
Scientific congresses and symposiums : Unpublished conference/Abstract
Life sciences : Genetics & genetic processes
Life sciences : Animal production & animal husbandry
Sustainable dairy farming - A case study of Holsteins in a developed and an emerging country
Hammami, Hedi mailto [Université de Liège - ULiège > 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 - ULiège > Gembloux Agro-Bio Tech > Gembloux Agro-Bio Tech >]
IDF World Dairy Summit 2009
20-24 septembre 2009
[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.
Researchers ; Professionals

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