Effects of different forms of canola oil fatty acids plus canola meal on milk composition and physical properties of butter

Twenty multiparous Holstein cows were used in a 16-wk trial. A block of 10 cows received a control diet, based on corn silage, and the other block of 10 cows successively received four diets with 1) an extruded blend of canol a meal and canola seeds, 2) canola meal and whole canola seeds, 3) canola m eal and ground canola seeds, or 4) canola meal and calcium salts of canola oil fatty acids. Canola fat represented about 2% of dietary dry matter. Com pared to control cows, treated cows had similar dry matter intake, milk pro duction, and daily milk output of true protein or fat. Protein contents of milk was decreased by all treatments, with a lower effect of extruded or wh ole canola seeds. Milk fat contents was lowered by all treatments, extruded seeds and calcium salts resulting in most important effects. All treatment s lowered the percentage of fatty acids with 12 to 16 carbons in milk fat, increased C-18:0 and cis-C-18:1 percentages, and the proportion of liquid f at in butter between 0 and 12 degrees C. Calcium salts and, to a lesser ext ent extruded seeds, resulted in most important improvements of milk fatty a cid profile and butter softness, whereas whole seeds had low effects.