Project: A cdna microarray to quantify nutritional effects on gene expression in peripartal dairy cows

Agency: USDA NRI

PI: Drackley, J.

Co-PI: Rodriguez-Zas, Sandra.

Grant Number: 2001-03324

Link: http://cris.csrees.usda.gov/

Abstract:

OBJECTIVES: 1) To determine how capacities of key pathways of fatty acid, glucose, and protein metabolism in liver and muscle are affected by different prepartum nutritional strategies. 2) To determine expression patterns for over 3,800 genes simultaneously in leukocytes, liver, and muscle as affected by different prepartum nutritional strategies. a) To provide a preliminary assessment of the degree of individual variability in expression patterns compared with expression patterns identified in pooled RNA from groups. b) To determine baseline changes in expression patterns from the end of lactation through parturition and into the subsequent lactation for healthy dairy cows fed according to current National Research Council standards. c) To identify genes and corresponding metabolic pathways that are differentially regulated by under or overnutrition during the prepartum period. APPROACH: Holstein dairy cows will be fed one of five diets during the far-off and close-up dry period, representing various combinations of under- or over-feeding and feeding to meet current National Research Council guidelines. Repeated samples of blood, liver, and muscle will be obtained during late gestation and early lactation. In vitro metabolism of fatty acids will be measured in liver slices. Portions of leukocytes, liver and muscle will be prepared and frozen for isolation of total RNA. A cDNA microarray representing over 3,800 bovine genes will be used to determine changes in gene expression patterns as physiological state changes from late gestation through early lactation, and to determine if dry period nutrition differentially affects gene expression patterns in these tissues. Differential expression of genes or groups of genes will be used to target processes that might be manipulated by management, nutritional, or pharmacological methods to improve transition success in dairy cows. NON-TECHNICAL SUMMARY: The transition period from 3 weeks before to 3 weeks after calving (the peripartal period) is the most critical phase of the lactation cycle for dairy cows. Suboptimal nutrition, management, or environment during this time may limit peak milk production, and the occurrence of health problems is centered disproportionately on this short period. Regulation of metabolism, health, and productivity in response to nutrition during late gestation is poorly understood. We will measure in vitro metabolic activities and use state-of-the-art cDNA microarray technology to determine expression patterns for over 3,800 genes simultaneously in peripartal dairy cows subjected to a control diet or various combinations of under- and over-feeding during late gestation. Normal patterns of gene expression will be quantified in liver, muscle, and leukocytes during late gestation and early lactation. Observed responses of metabolism, health, feed intake, and milk production will be related to gene expression patterns. Identification of differentially regulated genes, or groups of genes, and unique gene expression patterns associated with both optimal and turbulent transitions will provide a mechanistic basis for nutrition and management recommendations, as well as providing invaluable tools for further research. These experiments will provide the foundation for the field of nutritional genomics in cattle.

Publications:

Loor, J. J., J. K. Drackley, H. M. Dann, R. E. Everts, S. L. Rodriguez-Zas, and H. A. Lewin. 2003. Mammary gene expression analysis in peripartal dairy cows using a bovine cDNA microarray. Journal Animal Science, 81(Suppl. 1): W8.

Loor, J. J., J. K. Drackley, H. M. Dann, R. E. Everts, S. L. Rodriguez-Zas, and H. A. Lewin. 2003. Hepatic gene expression analysis in peripartal dairy cows using a bovine cDNA microarray. Journal Animal Science, 81(Suppl. 1): W9.