Milk concentrations of the mammalian lignans enterolactone and enterodiol, milk production, and whole tract digestibility of dairy cows fed diets containing different concentrations of flaxseed meal

A total of 32 lactating Holstein cows averaging 634 +/- 27 kg of body weight were allotted at week 33 of lactation to eight groups of four cows blocked for similar days in milk. The objective of the experiment was to determine the effect of feeding four dietary concentrations (0, 50, 100 or 150 g/kg of the dry matter (DM)) of flaxseed meal (FM), which contains the plant lignan precursor secoisolariciresinol diglucoside, on concentrations of two mammalian lignans enterodiol (ED) and enterolactone (EL) in milk. The effects of the four diets on feed intake, milk production, milk composition, and digestion were also studied. Cows within each block were assigned to one of the four isonitrogenous and isoenergetic total mixed diets and the experiment was carried out from week 33 to 37 of lactation. Diets were fed for ad libitum intake. The mammalian lignan ED was not detected in the milk of cows. Concentration of EL in milk increased linearly with the level of incorporation of FMI in the diet. Feed intake, milk yield, and milk composition were similar among diets, thus suggesting that FM is a good protein source for diets of mid-lactating dairy cows up to 150 g/kg of the DM and that FM is a feed ingredient enhancing concentration of the mammalian lignan EL in milk. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.