Type of Document Master's Thesis Author Loor, Juan Jose Author's Email Address jloor@vt.edu URN etd-111097-105853 Title Postruminal flow, digestibility, and utilization of fatty acylamides or conjugated linoleic acid for milk fat synthesis by lactating Holstein cows Degree Master of Science Department Dairy Science Advisory Committee
Advisor Name Title Herbein, Joseph H. Jr. Committee Chair Keenan, Thomas W. Committee Member Pearson, Ronald E. Committee Member Vinson, William E. Committee Member Keywords
- CLA
- bovinic acid
- oleic acid
- dairy cow
Date of Defense 1997-11-25 Availability restricted Abstract Four Holstein cows with ruminal and duodenal cannulas were usedto evaluate the effects of dietary fatty acylamides (canolamide)
or abomasally infused conjugated linoleic acid on milk production
and composition. In the first experiment, cows were fed diets
with no supplemental fat(control), or the control diet supplemented
at 3.3% of DM with canola oil, canolamide, or a mixture of equal
amounts of canola oil and canolamide in a 4 x 4 Latin square.
DMI and milk yield were decreased when cows were fed canolamide.
Intake and duodenal flow of diet components and fatty acids
were decreased by canolamide, but their apparent digestibilities
were not affected by treatment. Fat supplementation decreased
concentrations of fatty acids with 8 to 16 carbons and increased
oleic acid in milk. In the second experiment, cows were infused
abomasally with 100 g Linoleic acid (LA) or a mixture of 100 g
LA plus 100 g conjugated linoleic acid (LA-CLA) for 24 h in a
single crossover design. Infused CLA was a mixture of 70%
cis-9, trans-11-18:2 and 30% trans-10, cis-12-18:2. Milk yield
and DMI were not affected by treatment. Milk fat percentage
and yield were decreased by LA-CLA. Concentration and yield of
oleic and arachidonic acid and fatty acids with 6 to 16 carbons
in milk were reduced by LA-CLA. Stearic acid and CLA concentrations
in milk, however, were higher in response to LA-CLA. Infusion
of LA-CLA led to increased (from 23 to 45%) concentration of
unsaturated fatty acids with a concomitant decrease (from 70 to 42%)
in saturated fatty acid concentration in milk fat. Feeding
canolamide at 3.3% significantly decreased DMI and milk yield
compared with canola oil or the mixture of canola oil and
canolamide. However, results indicated that oleic acid and CLA
concetration in milk fat can be increased proportionally to
their flow into the small intestine. Utilization of these fatty
acids for milk fat synthesis may cause a reduction in the amount
of medium and short chain fatty acids synthesized de novo within
the mammary gland. Furthermore, CLA appears to be a potent
inhibitor of milk fat synthesis and desaturation of stearic and
linoleic acid.
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