Project Number: 8042-31310-078-002-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 28, 2018
End Date: Sep 27, 2023
The objective of the collaborative project is to determine whether specific plasma indicators including blood metabolites and markers of inflammation are associated with measures of feed efficiency in growing dairy heifers evaluated between 10 and 14 months of age.
Blood samples will be collected from growing dairy heifers (10 -14 months of age) that are being evaluated for feed efficiency (measured as residual feed intake) from the USDA-ARS Beltsville Holstein herd. Blood will be collected monthly during a controlled growth trial (4 samples per heifer) for separation of plasma. Approximately 60 heifers will be evaluated per year for a period of 4 years. Samples will be analyzed for metabolites beta hydroxybutyrate, non-esterified fatty acids, albumin, and aspartate amino transferase. The association between plasma indicators and residual feed intake will be analyzed by regression analysis. Concentrations of each plasma indicator will also be compared between heifers with high and low residual feed intake using means comparison tests.