Whole‐genome association study for energy balance and fat/protein ratio in German Holstein bull dams

Abstract

The metabolic status of cows is important to health and fertility, especially in early lactation, and energy balance (EB) and fat/protein ratio (FPR) are considered as appropriate indicators for metabolic disorders. The aim of this study was to detect SNPs (single nucleotide polymorphisms) associated with EB and FPR in German Holstein bull dams belonging to the research herd Karkendamm. Bull dams were genotyped using the Illumina Bovine SNP 50K Bead chip(®) comprising 54 001 SNPs. A total of 43 593 SNPs and 586 (EB) and 668 (FPR) bull dams passed the quality control criteria. Phenotypes were deregressed breeding values estimated via random regression animal models for lactation days 11, 20, 30, and 42 for EB and FPR. Whole-genome association analyses were carried out fitting principal components as covariates to adjust for genetic substructure. Permutation tests were applied to estimate genome-wise significance. Across all observed lactation days, 19 SNPs located in four different intervals on chromosomes 1, 14, 16, and 27 were detected. For EB, seven markers across four chromosomes were identified. There was no overlap between markers associated with FPR and EB. SNPs associated with FPR were mostly located in QTL regions for milk production traits, especially in the region of DGAT1, whereas SNPs associated with EB mainly showed positional relationships to previously described QTL regions affecting functional traits, especially fertility.

Genetic effects and correlations between production and fertility traits and their dependency on the lactation-stage in Holstein Friesians

“…In those first weeks, the cow needs to draw energy from its adipose stores and in some cases even from its muscles, leading to a loss in body weight. The nutritional status of a cow after calving affects disease resistance and reproductive performance and regions affecting energy status were reported to overlap with regions significant for fertility traits [14]. On one hand, for many populations, an unfavorable correlation between fertility traits and milk production has been reported due to the competition between these traits for the same body resources [15-19].…”

GWAS and Fine-Mapping of Livability and Six Disease Traits in Holstein Cattle

“…A previous candidate gene association study by Tetens et al (2013) proposed DGAT1 to be an indicator of ketosis [30]. In that study, the DGAT1 gene was determined to be involved in cholesterol metabolism, which is known to be an indicator of a ketogenic diet in humans [30]. This result highlights a potential pathway in the pathogenesis of ketosis that may be an area for future research.…”

“…This gene is located close to the DGAT1 gene that affects milk fat composition. A previous candidate gene association study by Tetens et al (2013) proposed DGAT1 to be an indicator of ketosis [30]. In that study, the DGAT1 gene was determined to be involved in cholesterol metabolism, which is known to be an indicator of a ketogenic diet in humans [30].…”

Genome‐wide association study identifies energy metabolism genes for resistance to ketosis in Chinese Holstein cattle

“…) and associated with the fat:protein ratio in primiparous German Holsteins (Tetens et al . ). A high fat:protein ratio has been shown to be associated with a higher risk for KET incidence (Jenkins et al .…”