RESUMO
A total of 24 lactating Holstein cows averaging 620 (SE=29) kg of body weight were allotted at week 17 of lactation to eight groups of three cows blocked for similar days in milk to determine the effects of feeding two sources of the plant lignan precursor secoisolariciresinol diglucoside, whole flaxseed and flaxseed meal, on concentrations of the mammalian lignans (enterodiol and enterolactone) in milk. Feed intake, digestion, milk production and milk composition were also determined to compare the use of whole flaxseed and flaxseed meal for milk production. Cows within each block were assigned to one of the three isonitrogenous and isoenergetic total mixed diets: no flaxseed product; 10% flaxseed meal; or 10% whole flaxseed in the dry matter. The experiment was carried out from week 17 to week 21 of lactation and diets were fed at ad-libitum intake. The mammalian lignan, enterodiol, was not detected in the milk of cows. Cows fed whole flaxseed and flaxseed meal had greater concentrations of enterolactone in milk than those fed the control diet. Feed intake, milk production and milk composition were also similar for all diets, indicating that both flaxseed meal and whole flaxseed are suitable feed ingredients for milk production of cows in mid lactation. The results provide new information on the conversion of plant secoisolariciresinol diglucoside from two flaxseed products into mammalian lignans in dairy cows.
