FATTY-ACID PROFILE AND PHYSICAL-PROPERTIES OF MILK-FAT FROM COWS FED CALCIUM SALTS OF FATTY-ACIDS WITH VARYING UNSATURATION

Holstein cows (n = 24) averaging 42 d in milk were used in a randomize d complete block design during a 4-wk trial. A control total mixed rat ion (TMR) was compared with TMR supplemented with Ca salts of fatty ac ids from canola oil, soybean oil, or linseed oil. The three vegetable oils were progressively more unsaturated; the dominant fatty acids wer e, respectively, cis-Delta-9-C-18:1,C- C-18:2,C- and C-18:3. Apparent total tract digestibility of dry matter, crude protein, ether extract, and neutral detergent fiber was higher for rations containing Ca salt s than for the control ration. Milk yield increased linearly as the un saturation of the dominant fatty acid in the Ca salts increased. Milk fat percentage was reduced when Ca salts were added to the rations. Th e addition of Ca salts to the ration decreased the proportions of satu rated fatty acids that contained C-6 to C-16 and increased the proport ions of C-18:0, cis-Delta-9-C-18:1, and trans-Delta-11-C-18:1 1 in mil k fat. Proportions of C-18:2 and C-18:3 increased linearly, and cis-De lta-9-C-18:1 decreased linearly, as the unsaturation of the dominant f atty acid in the Ca salts increased. The proportion of fat that was li quid at 5 degrees C was higher for butter from cows fed diets containi ng Ca salts, but the proportion of liquid fat at 20 degrees C was not affected. Calcium salts of unsaturated fatty acids added to the diets of dairy cows improved the thermal properties of milk fat.