Regulation and Integration of Hepatic Function With Mammary and Adipose Metabolism in Holstein Cows
Selection practices have truly transformed the phenotypic and genotypic character of the Holstein cow and tremendously increased milk and component yields per U.S. Holstein since the 1960s. These increases have dramatically altered metabolic fluxes in the cow to support the increased demand for nutrients to synthesize milk and have been associated with reduced reproductive performance and with increased susceptibility to metabolic disorders, especially during the periparturient period. Failure to successfully transition from pregnancy to lactation decreases cow well-being and is detrimental to the economic viability of dairy enterprises. Considerable effort has been expended to understand factors that regulate metabolism during the transition period and progress has been achieved but specific mechanisms that regulate how cows partition nutrients among body functions have not been identified. These researchers use transcriptome analysis (RNA-Seq) to identify potential mechanisms responsible for this coordinated regulation of tissue metabolism. Hepatic, adipose, and mammary tissue biopsies from 10 low-merit and 10 high-merit cows will be collected at 4 timepoints (8 x 2 x 3 x 4 = 240 samples) and sequenced to obtain 20 million paired-end reads (50 bp) per sample. Sequences will be aligned to the UMD3.0 assembly using Bowtie, splice junctions will be identified using TopHat, and de novo transcript assembly and exon abundance analysis will be performed using Cufflinks. Results will be normalized and effects on abundance differences assessed using JMP Genomics.
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