A search for quantitative trait loci for milk production traits on chromosome 6 in Finnish Ayrshire cattle.
Cattle chromosome 6 was scanned with 11 markers, ten microsatellites and the casein haplotype, to identify quantitative trait loci (QTLs) affecting the following milk production traits: milk yield, fat percentage, fat yield, protein percentage and protein yield. Twelve Finnish Ayrshire half-sib families with a total of 480 sons were genotyped and used in a grand-daughter design. Interval mapping was performed with a multiple-marker regression approach with a one-QTL and a two-QTL model, and the significance threshold values were determined empirically using a permutation test. Across-family analysis with the one-QTL model revealed an effect on protein percentage (P < 0.05) and on milk yield (P < 0.05). The analysis with the two-QTL model identified significant effects (P < 0.05) on protein percentage, milk yield, and fat yield. Comparing these two cases, the results suggest the existence of two QTLs on chromosome 6 with an effect on milk production traits. One of the QTLs was located around the casein genes. As the other QTL was similar in location and effect to a QTL found previously in Holstein-Friesians, an identity-by-descent approach could be applied to fine map this region.
Velmala
R J
RJ
Animal Breeding, Institute of Animal Production, Agricultural Research Centre, Jokioinen, Finland.
Vilkki
H J
HJ
Elo
K T
KT
de Koning
D J
DJ
Mäki-Tanila
A V
AV
D000818:Animals; D002364:Caseins / Q000235:genetics; D002417:Cattle / Q000235:genetics* / Q000502:physiology; D002874:Chromosome Mapping / Q000662:veterinary; D003198:Computer Simulation; D017931:DNA Primers / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D005260:Female; D005387:Finland; D007178:Inbreeding; D007774:Lactation / Q000235:genetics*; D008055:Lipids / Q000096:biosynthesis / Q000235:genetics; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D008892:Milk / Q000378:metabolism*; D008894:Milk Proteins / Q000096:biosynthesis / Q000235:genetics; D008957:Models, Genetic; D016133:Polymerase Chain Reaction / Q000662:veterinary; D019655:Quantitative Trait, Heritable; D012044:Regression Analysis; D012661:Semen / Q000737:chemistry
D002364:Caseins; D017931:DNA Primers; D008055:Lipids; D008894:Milk Proteins