Title page for ETD etd-06292012-144218


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
  • FABP
  • lipid metabolism
  • transfer efficiency
  • rumen protection
  • n-3 fatty acid
Date of Defense 2012-06-25
Availability restricted
Abstract
Marine 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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