Whole flaxseed and Ca-salts of flaxseed oil supplying
0.7 to 1.4% of fat (4.2% of whole flaxseed, 1.9% of Casalts of flax oil, or 2.3% of flaxseed whole + 0.8% calcium salts of flaxseed oil) in the diets of dairy cows had
no effect on feed intake, apparent digestibility of DM,
or milk production. Calcium salts of flaxseed oil fed at 1.9% of DM decreased milk fat concentration compared
with a control diet, whereas concentrations of protein,
lactose, urea N, and total solids in milk were not affected. Calcium salts of flaxseed oil fed at 0.8 and 1.9%
of the dietary DM increased concentrations of rumenic
acid and intermediates of biohydrogenation (trans-9
18:1) in milk fat compared with whole flaxseed and
increased α-linolenic acid concentration compared with
a control diet. Milk fat concentration of α-linolenic acid
was increased by feeding 1.9% Ca-salts of flaxseed oil
and a mixture of 0.8% Ca-salts of flaxseed oil and 2.3%
whole flaxseed compared with feeding a control diet.
However, all diets supplemented with flaxseed products
had similar concentrations of α-linolenic acid in milk
fat. All flaxseed products (whole flaxseed and Ca-salts)
decreased the n-6 to n-3 fatty acid ratio in milk fat. Results confirm that flax products supplemented at 1.5%
of fat in the diet could slightly improve the nutritive
value of milk fat.