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Gastrointestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition

Njåstad, Kari Marie; Adler, Steffen A.; Hansen-Møller, Jens; Thuen, Erling; Gustavsson, Anne-Maj and Steinshamn, Håvard (2014) Gastrointestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition. Journal of Dairy Science, 97 (12), pp. 7735-7750.

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Document available online at: http://www.journalofdairyscience.org/article/S0022-0302(14)00690-0/abstract


Dietary phytoestrogens are metabolized or converted in the gastrointestinal tract of ruminants, only limited knowledge exists on the extent and location of this conversion in vivo. The objective of this study was to quantify the gastro-intestinal metabolism of phytoestrogens in lactating dairy cows fed silages with different botanical composition. Four lactating rumen cannulated Norwegian Red cattle were assigned to a 4?4 Latin square with 1 cow per treatment period of 3 wk. The 4 treatment silages were prepared from grasslands with different botanical compositions: organically managed short-term timothy (Phleum pratense L.) and red clover (Trifolium pratense L.) ley (2 yr old: ORG-SG); organically managed long-term grassland with a high proportion of unsown species (6 yr old; ORG-LG); conventionally managed perennial ryegrass (Lolium perenne L.) ley (CON-PR); and conventionally managed timothy ley (CON-TI). The herbages were cut, wilted, and preserved with additive in round bales, fed as a mix of the first and third cut at 90% of ad libitum intake, and contributed to 70% of the total dry matter intake. Milk, feed, omasal digesta, urine, and feces were collected at the end of each period and analyzed for the concentrations of phytoestrogens by using a liquid chromatography?tandem mass spectrometry technique. Concentration of total isoflavones was highest in ORG-SG and lowest in CON-TI silage, whereas the content of total lignans was highest in the grass silages. The isoflavones were extensively metabolized in the rumen on all diets, and the recovery of formononetin and daidzein in omasum, mainly as equol, averaged 0.11mg/mg. The apparent intestinal metabolism was less severe as, on average, 0.29mg/mg of the omasal flow was recovered in feces. The plant lignans were also strongly degraded in the rumen. However, the flow of lignans to omasum and excretion in feces were, on average, 7.2- and 5.2-fold higher, respectively, than the intake of the plant lignans matairesinol and secoisolariciresinol, known as precursors of mammalian lignans. Thus, excretion to milk could not be directly related to intake, implying that plant lignans other than matairesinol and secoisolariciresinol in forage are precursors for enterolactone production in the rumen and for its content in milk. Equol followed mainly the flow of large particles out of the rumen, whereas the mammalian lignans were distributed between phases proportional to dry matter flow. The main metabolism of phytoestrogens occurred in the rumen and the main route of excretion was through feces and urine, with only a small part being excreted in milk. The concentration of phytoestrogens in milk can be manipulated through intake but the intermediate transfer capacity to milk appears to be limited by saturation.

EPrint Type:Journal paper
Keywords:isoflavone lignan silage recovery
Subjects: Animal husbandry > Production systems > Dairy cattle
Food systems > Food security, food quality and human health
Animal husbandry > Feeding and growth
Research affiliation: European Union > CORE Organic > PHYTOMILK
Denmark > AU - Aarhus University > AU, DJF - Faculty of Agricultural Sciences
Norway > NMBU - Norwegian University of Life Sciences
Norway > Bioforsk - Norwegian Institute for Agriculture and Environmental Research > Bioforsk Organic Food and Farming Division
Sweden > Swedish University of Agricultural Sciences (SLU) > Department of Agricultural Research for Northern Sweden
DOI:http://dx.doi.org/ 10.3168/jds.2014-8208
Deposited By: Steinshamn, Dr Håvard
ID Code:27827
Deposited On:11 Dec 2014 09:36
Last Modified:11 Dec 2014 09:36
Document Language:English
Refereed:Peer-reviewed and accepted

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