|Van Tassell, Curtis|
Submitted to: BARC Poster Day
Publication Type: Proceedings
Publication Acceptance Date: April 8, 1999
Publication Date: N/A
Technical Abstract: Quantitative trait loci (QTL) affecting milk yield, health, and type traits were studied for seven large US Holstein grandsire families using the granddaughter design. Families were genotyped for 20 microsatellite markers, and marker effects were analyzed for 28 traits (21 type traits, 5 milk traits, somatic cell score (SCS), and productive life) and 16 canonical traits derived from type and production traits. Permutation tests were used to calculate experiment-wise error rates. A critical value of P = 0.1 was used to determine significance. Associations were identified for protein yield and teat length with markers from chromosomes 6 and 29 with estimated allelic differences of 2.6 kg protein and 0.87 genetic standard deviations, respectively. One marker on chromosome 7 was associated with SCS and protein percentage in different families. Estimated allelic differences were 0.051 % protein and 0.135 units of SCS. Markers located on chromosomes 14 and 29 were individually associated with fore udder attachment in one family and were subsequently analyzed jointly with estimated allele differences of 1.06 and 0.73 genetic standard deviations. Across family analyses identified a marker associated with a DNA region affecting both fat and protein percentages on chromosome 3 and markers affecting stature and udder composite on chromosomes 29 and 14. Finally, markers on chromosomes 4 and 9 provided evidence for differences in families for canonical type trait 1 and canonical production trait 2, respectively. These 20 microsatellite markers supplement the original 70 markers, which have been completed in these 7 Holstein families. Additional markers are being added to allow interval analysis where putative QTL have been identified and to increase marker density.