Effects of Abomasal Infusions of Safflower Oil or Elaidic Acid on Blood Lipids and Milk Fat in Dairy Cows

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Abstract
In each of three trials with abomasally- fistulated lactating Holstein cows, we compared control rations to the same ra- tion plus abomasal infusion of safflower oil or elaidie acid. In Trial 1, 250 m) safflower oil were infused over 4 h daily for 3 wk. Trial 2 involved infusing 560 ml safflower oil over 4 h daily for 1 wk. In Trial 3 elaidic acid was infused daily for 1 wk. Infusion of safflower oil in Trial 1 in- creased milk fat percentage and propor- tion of 18-carbon polyunsaturated fatty acids in the milk fat. Proportions of my- ristic, pahnitic, stearic, and o!eic fatty acids of milk fat decreased. Blood ke- tones and free: fatty acids and cholesterol of plasma were increased by the oil in- fusion. In Trial 2 the 1-wk infusion of saf- flower oil did not affect milk fat yield or percentage. The infusion increased the proportion of polyunsaturated 18-carbon fatty acids in the, milk fat and decreased myristate, palmitate, and stearate. An in- crease in plasma free, fatty acid was small but significant. Triglycerides, cholesterol, glucose, ketones, and acetate were not affected by the infusion. Intake of hay was depressed by this infusion rate. In Trial 3, infusion of elaidie acid had no effect on milk fat yield or percentage. Blood or plasma lipids did not change.