ORBi: Hammami Hedi - Environmental sensitivity for milk yield in Luxembourg and Tunisian Holsteins by herd management level.

Reference : Environmental sensitivity for milk yield in Luxembourg and Tunisian Holsteins by herd ma...


	Document type :	Scientific journals : Article
	Discipline(s) :	Life sciences : Food science Life sciences : Genetics & genetic processes Life sciences : Animal production & animal husbandry
	To cite this reference:	http://hdl.handle.net/2268/25295

Title :	Environmental sensitivity for milk yield in Luxembourg and Tunisian Holsteins by herd management level.
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 (ESAM) > > >Productions animales > > > >]
	Bastin, Catherine [Université de Liège - ULg > Gembloux Agro-Bio Tech > Gembloux Agro-Bio Tech > > >]
	Soyeurt, Hélène [Université de Liège - ULg > Gembloux Agro-Bio Tech > Gembloux Agro-Bio Tech >]
	Bormann, Jeanne [Administration des Services Techniques de l'Agriculture, Luxembourg > > > >]
	Stoll, Jean [>Convis Herdbuch Service élevage et génétique > > >R&D > > >]
	Gengler, Nicolas [Université de Liège - ULg > Gembloux Agro-Bio Tech > Gembloux Agro-Bio Tech >]
Publication date :	2009
Journal title :	Journal of Dairy Science
Publisher :	American Dairy Science Association
Volume :	92
Issue/season :	9
Pages :	4604-12
Audience :	International
ISSN :	0022-0302
e-ISSN :	1525-3198
City :	Champaign
Country :	IL
Keywords :	[en] environmental sensitivity ; genotype by environment interaction ; genetic correlation ; herd management level
Abstract :	[en] Milk production data of Luxembourg and Tunisian Holstein cows were analyzed using herd management (HM) level. Herds in each country were clustered into high, medium, and low HM levels based on solutions of herd-test-date and herd-year of calving effects from national evaluations. Data from both populations included 730,810 test-day (TD) milk yield records from 87,734 first-lactation cows. A multi-trait, random regression TD model was used to estimate (co)variance components for milk yield within and across country HM levels. Additive genetic and permanent environmental variances of TD milk yields varied with management level in Tunisia and Luxembourg. Additive variances were smaller across HM levels in Tunisia than in Luxembourg, whereas permanent environmental variances were larger in Tunisian HM levels. Highest heritability estimates of 305-d milk yield (0.41 and 0.21) were found in high HM levels, whereas lowest estimates (0.31 and 0.12, respectively) were associated with low HM levels in both countries. Genetic correlations among Luxembourg HM levels were >0.96, whereas those among Tunisian HM levels were below 0.80. Respective rank orders of sires ranged from 0.73 to 0.83 across Luxembourg environments and from 0.33 to 0.42 across Tunisian HM levels indicating high re-ranking of sires in Tunisia and only a scaling effect in Luxembourg. Across-country environment analysis showed that estimates of genetic variance in the high, medium, and low classes of Tunisian environments were 45, 69, and 81% lower, respectively, than the estimate found in the high Luxembourg HM level. Genetic correlations among 305-d milk yields in Tunisian and Luxembourg HM environments ranged from 0.39 to 0.79. The largest estimated genetic correlation was found between the medium Luxembourg and high Tunisian HM levels. Rank correlations for common sires' estimated breeding values among HM environments were low and ranged from 0.19 to 0.39, implying the existence of genotype by environment interaction. These results indicate that daughters of superior sires in Luxembourg have their genetic expression for milk production limited under Tunisian environments. Milk production of cows in the medium and low Luxembourg environments were good predictors of that of their paternal half-sisters in the high Tunisian HM level. Breeding decisions in low-input Tunisian environment should utilize semen from sires with daughters in similar production environments rather than semen of bulls proven in higher management levels.
Funders :	FNR Luxembourg
Target :	Researchers
Permalink :	http://hdl.handle.net/2268/25295
DOI :	10.3168/jds.2008-1513
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