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Genetic Diversity and Joint-Pedigree Analysis of Two Importing Holstein Populations

H. Hammami^*,, C. Croquet^*,, J. Stoll, B. Rekik^|| and N. Gengler^*,,1

^* Animal Science Unit, Gembloux Agricultural University, B-5030 Gembloux, Belgium
Livestock and Pasture Office, 1002 Tunis Belvedere, Tunisia
National Fund for Scientific Research, B-1000 Brussels, Belgium
CONVIS Herdbuch, Service Elevage et Génétique, L-9004 Ettelbruck, Luxembourg
^|| Ecole Supérieure d’Agriculture de Mateur, 7030 Mateur, Tunisia

¹ Corresponding author: gengler.n{at}fsagx.ac.be

Genetic diversity and relatedness between 2 geographically distant Holstein populations (in Luxembourg and Tunisia) were studied by pedigree analysis. These 2 populations have similar sizes and structures and are essentially importing populations. Edited pedigrees included 140,392 and 151,381 animals for Tunisia and Luxembourg, respectively. To partially account for pedigree completeness levels, a modified algorithm was used to compute inbreeding. The effective numbers of ancestors were derived from probabilities of gene origin for the 2 populations of cows born between 1990 and 2000. The 10 ancestors with the highest contributions to genetic diversity in the cow populations accounted for more than 32% of the genes. Eight of these 10 ancestors were the same in both populations. The rates of inbreeding were different in the 2 populations but were generally comparable to those found in the literature for the Holstein breed. Average inbreeding coefficients per year, estimated from the data, ranged from 0.91 and 0.50 in 1990 to 3.10 and 2.12 in 2000 for the Tunisian and Luxembourg populations, respectively. Genetic links have also strengthened with time. Average additive relationships between the 2 populations were as high as 2.2% in 2000. Results suggest that it would be possible to investigate genotype by environment interactions for milk traits using the Tunisian and Luxembourg dairy populations.

Key Words: pedigree • probability of gene origin • inbreeding • genetic diversity

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				H. Hammami, B. Rekik, H. Soyeurt, C. Bastin, J. Stoll, and N. Gengler Genotype x Environment Interaction for Milk Yield in Holsteins Using Luxembourg and Tunisian Populations J Dairy Sci, September 1, 2008; 91(9): 3661 - 3671. [Abstract] [Full Text] [PDF]

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