Genome-wide associations for investigating time-dependent genetic effects for milk production traits in dairy cattle |
| |
Authors: | Strucken E M Bortfeldt R H de Koning D J Brockmann G A |
| |
Affiliation: | 1. Breeding Biology and Molecular Genetics, Department for Crop and Animal Sciences, Faculty of Agriculture and Horticulture, Humboldt‐Universit?t zu Berlin, Invalidenstrasse 42, D‐10115 Berlin, Germany.;2. Roslin Institute and R(D)SVS, University of Edinburgh, EH25 9RG Roslin, UK.;3. Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 7023, 750 07 Uppsala, Sweden |
| |
Abstract: | Phenotypic variation in milk production traits has been described over the course of a lactation as well as between different parities. The objective of this study was to investigate whether variation in production is affected by different loci across lactations. A genome-wide association study (GWAS) using a 50-k SNP chip was conducted in 152 divergent German Holstein Friesian cows to test for association with milk production traits over different lactations. The first four lactations were analysed regarding milk yield, fat, protein, lactose, milk urea nitrogen yield and content as well as somatic cell score. Two approaches were used: (i) Wilmink curve parameters were used to assess the genetic effects over the course of a lactation and (ii) test-day yield deviations (YD) were used as a normative approach for a GWAS. The significant effects were largest for markers affecting curve parameters for which there was a statistical power <0.8 of detection even in this small design. While significant markers for YDs were detected in this study, the power to detect effects of a similar magnitude was only 0.11, suggesting that many loci may have been missed with this approach in the present design. Furthermore, all significant effects were specific for a single lactation, leading to the conclusion that the variance explained by a certain locus changes from lactation to lactation. We confirm the common evidence that most production traits vary in the degree of persistency after the peak as a result of genetic influence. |
| |
Keywords: | genome‐wide association study Holstein Friesian dairy cattle lactation curve Wilmink curve |
本文献已被 PubMed 等数据库收录! |
|