Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/14/2009
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: The mRNA transcript abundance in a cell or tissue is a heritable and quantitative trait that corresponds to the status of gene expression. This principle has been widely applied, using microarrays to identify core regulatory genes for physiological and pathological traits in plants and animals. Gene expression patterns in tissue may serve as a biomarker for genetic stature or physiological condition. Our laboratory conducted a six-year study with the objective of generating a “gene expression index” that will predict genetic merit for milk yield (MY) in dairy cattle. The underlying hypothesis is that heritable expression patterns associated with MY are reflected in the peripheral leukocyte transcriptome. An oligonucleotide microarray of more than 13,000 genes was used to identify associations between leukocyte transcript levels and predicted transmitted ability (PTA) for MY. Experimental animals consisted of two groups of age-matched Holstein-Friesian heifers from one herd: a pilot study (N=19) sampled in 2002, and a confirmatory study (N=58) sampled in 2005 and 2006. Microarray data were subjected to stringent quality controls and analyzed using multivariate ANOVA. We identified 69 differentially expressed genes in the pilot study group and one in the confirmatory study group. Quantitative real time PCR (qRT-PCR) was used to confirm microarray results for 15 selected candidate genes. Expression levels of five genes were confirmed predictive of PTA for MY by qRT-PCR. Our results suggest that it is possible to use mRNA abundant levels and expression patterns in peripheral blood to predict genetic merit for MY prior to a cow’s first lactation.