Title page for ETD etd-111097-105853


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 used

to 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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