EFFECT OF DIFFERENT LIPIDS IN RATION OF LACTATING DAIRY COWS ON COMPOSITION OF MILK

Twelve Holstein cows were assigned to three blocks of a 4 × 4 Latin-square experimental design. The within-block treatments were: control, 1% Degras wool fat (48.3% cholesterol), 1% mixed soy sterols and a mixture of 0.5% Degras fat, and 0.5% of soy sterols of the concentrate mixture. The concentrates between blocks contained no added fat, 10% animal tallow, or 10% vegetable oil. Milk fat production, fat test, and fat-corrected milk production were highest when no sterol was added to the ration. Percentages solids-not-fat, milk cholesterol, and blood fat were apparently not affected by the different sterols. However, cows had lower blood cholesterol when a mixture of animal and plant sterols was fed compared to other groups. Milk production, milk fat production, fat-corrected milk, blood fat, and blood cholesterol were significantly higher when either tallow or vegetable oil was fed. However, milk fat test was significantly lower. Milk fat production, solids-not-fat, and milk cholesterol were not significantly affected by fat source. © 1969, American Dairy Science Association. All rights reserved.