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Genotype by environment interaction for milk production traits in Tunisian Holstein dairy

Friday, August 22, 2014
Posters (The Westin Bayshore)
Abir Hamrouni , Institut National Agronomique de Tunise, Rude de kornich Chot El Salem Gabès, Tunisia
M'Naouer Djemali , 2Carthage University-INAT-TUNISIA, Laboratoire des Ressources Animales et Alimentaires, 1082 Cité Mahrajène,Tunisia, Tunis, Tunisia
Sonia Bendhiaf , Institut National de Recherche Agronomique de Tunis, Tunis, Tunisia
Abstract Text:

The data consisted of 37118 TD milk record of 5851 primiparous Holstein cows of Tunisia. Herd-years of calving means for milk production traits were clustered in three levels using the CLUSTER procedure in SAS software. Production levels included low, medium and high levels. Genotype by environment interaction were investigated by applying a sire model. Generally, the highest heritability estimates of 305-d milk production traits were found in high level rather than low level. Genetic correlation between expression in low and high level was 0,14 for milk yield, 0,22 for fat yield and 0,18 for protein yield. Low spearman correlations (ranged from 0,08 to 0,50) between estimated of the 74 common sires showed re-ranking of sires for these levels. Results from this research indicated that milk production of daughters of the same sires depends greatly on the production environment.  

Keywords:

dairy cattle

genotype by environment interaction

genetic correlations

Cluster analysis