%0 Journal Article
%T Casein haplotypes and their association with milk production traits in Norwegian Red cattle
%A Heidi Nilsen
%A Hanne Olsen
%A Ben Hayes
%A Erling Sehested
%A Morten Svendsen
%A Torfinn Nome
%A Theo Meuwissen
%A Sigbj£¿rn Lien
%J Genetics Selection Evolution
%D 2009
%I BioMed Central
%R 10.1186/1297-9686-41-24
%X Several studies have reported the existence of QTL affecting milk production traits on bovine chromosome 6 (BTA6) [1,2] (summarized at http://genomes.sapac.edu.au/bovineqtl/ webcite and http://www.vetsci.usyd.edu.au/reprogen/QTL_Map/ webcite). Two distinct regions on this chromosome affect milk traits (including protein yield, protein percentage, fat yield, fat percentage and milk yield). One QTL affecting protein and fat percentage has been positioned in a narrow region of 420 kb [3] and a putative functional polymorphism in the ABCG2 gene underlying the QTL has been suggested [4,5]. The second region on BTA6 associated with milk traits maps to the casein cluster [e.g. [6-11]]. The casein cluster is composed of four genes; ¦Ás1-, ¦Â-, ¦Ás2- and ¦Ê-casein (CSN1S1, CSN2, CSN1S2 and CSN3, respectively) producing approximately 80 percent of the protein content of cow's milk [12]. The four casein genes have been mapped in the order CSN1S1-CSN2-CSN1S2-CSN3 to bovine chromosome 6 (BTA6) at q31-33 by in situ hybridisation [13,14].Several polymorphisms have been detected in the open reading frame (reviewed by [12]) and in noncoding regions such as the 5'-flanking region of the casein genes [15,16]. The most common genetic variants in western dairy breeds are ¦Ás1-casein B (here denoted CSN1S1_192*A) and C (CSN1S1_192*G), ¦Â-casein A1 (CSN2_67*A), A2 (CSN2_67*C) and B (CSN2_122*C), and ¦Ê-casein A (CSN3_136*C), B (CSN3_136*T) and E (CSN3_155*G).In the present study, we have constructed a dense SNP map in the casein region. The map facilitates accurate haplotype construction and was used for comprehensive association studies in Norwegian Red cattle.All animals in the study belonged to the Norwegian Red cattle breed. For the chromosome wide QTL scan, animals were organized in a granddaughter design consisting of 18 elite sire families with a total of 716 sons and 507,000 granddaughters. To fine-map QTL in the casein region, the animal data was expanded to 31 elite sire families with
%U http://www.gsejournal.org/content/41/1/24