Type of Document Dissertation Author Stamey, Jennifer Anne URN etd-06292012-144218 Title Systemic and Intracellular Trafficking of Long-chain Fatty Acids in Lactating Dairy Cattle Degree PhD Department Dairy Science Advisory Committee
Advisor Name Title Corl, Benjamin A. Committee Chair Akers, Robert Michael Committee Member Hanigan, Mark D. Committee Member Hulver, Matthew W. Committee Member Petersson-Wolfe, Christina S. Committee Member Keywords
- lipid metabolism
- transfer efficiency
- rumen protection
- n-3 fatty acid
Date of Defense 2012-06-25 Availability restricted AbstractMarine oils are used as ration additives to provide omega-3 fatty acids to dairy
cows. Supplementing dairy cows with omega-3 fatty acid-rich feeds does not easily
increase quantities in milk fat of dairy cows because polyunsaturated fatty acids are
biohydrogenated in the rumen. Lipid encapsulation of omega-3 fatty acids provides
protection from biohydrogenation in the rumen and allows them to be available for
absorption and utilization in the small intestine. Lactating cows were supplemented with
rumen protected algae biomass or algal oil in a 4 × 4 Latin Square. Feeding lipid
encapsulated algae supplements increased docosahexaenoic acid content in milk fat while
not adversely impacting milk fat yield; however, docosahexaenoic acid was preferentially
esterified into plasma phospholipid, limiting its incorporation into milk fat. In the second
study, triglyceride emulsions of oils enriched in either oleic, linoleic, linolenic, or
docosahexaenoic acids were intravenously infused to avoid confounding effects of
triglyceride esterification patterns in the small intestine and to compare mammary uptake.
Milk transfer of fatty acids delivered as intravenous triglyceride emulsions was reduced
with increased chain length and unsaturation. Increased target fatty acids were evident in
plasma phospholipid, suggesting re-esterification in the liver. Transfer efficiencies were 37.8, 27.6, and 10.9±5.4% for linoleic, linolenic, and docosahexaenoic acid. Both liver
and mammary mechanisms may regulate transfer of long-chain polyunsaturates.
Intracellular fatty acid binding proteins (FABP) are cytoplasmic proteins that are
hypothesized to be essential for fatty acid transport and metabolism by accelerating longchain
fatty acid uptake and targeting to intracellular organelles, such as the endoplasmic
reticulum for triglyceride esterification. FABP3 mRNA is highly expressed in bovine
mammary and heart tissue, but is not present in MAC-T cells, a bovine mammary
epithelial cell line. When overexpressed in MAC-T cells, FABP3 does not appear to be
rate-limiting for fatty acid uptake in vitro and did not alter lipid metabolism. The function
of FABP3 in the mammary gland remains unclear.
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