A 2 × 2 factorial continuous experiment was conducted
with 28 Norwegian Red dairy cows in early lactation
to compare milk content of phytoestrogens when
feeding ad libitum white clover (WCS) or red clover
(RCS) grass silages prepared from the second and third
cut without and with 10 kg/d supplementation of a standard
concentrate. The cows were offered either RCS or
WCS for 88 d (period 1) and thereafter a mixed red
clover-white clover-grass silage for 48 d (period 2). Total
dry matter intake and milk yield were not affected by
forage type but increased with concentrate supplementation.
Intake of isoflavones was several times greater
in RCS than in WCS, whereas intake of lignans was
greater in WCS. Concentrate supplementation reduced
the intake of most phytoestrogens. Compared with
WCS, RCS diets yielded milk with a greater content of
flavonoids, whereas milk from WCS diets had greater
contents of the mammalian lignans enterodiol and enterolactone.
The content of the isoflavan equol was particularly
high in RCS diets. There was no apparent
carryover effect of clover type on milk phytoestrogen
content because there was no difference in content between
the silage treatments 3 wk after the cows were
transferred to the same silage diet (period 2). Concentrate
supplementation reduced the milk contents of the
flavonoids equol, biochanin A, and daidzein and increased
the content of mammalian lignans. The effects
of silage type and concentrate supplementation on milk
contents of the individual phytoestrogens were related
to the intake of the compound or its precursor, except
for the effect of concentrate on mammalian lignans,
for which the intake of the known precursors was also
reduced. Overall, this study shows that feeding cows
with silage containing red clover increases the milk
content of flavonoids at both low and high concentrate
Received November 13, 2007.
Accepted March 3, 2008.
1Corresponding author: havard.steinshamn@bioforsk.no
2715
supplementation levels, and decreases the content of
nonflavonoids such as mammalian lignans, when compared
with silage containing white clover. The increased
content of phytoestrogens in milk may be important
when the health benefits of milk are studied.
Key words: clover species, concentrate level, milk phytoestrogen
content, equol
A 2 × 2 factorial continuous experiment was conductedwith 28 Norwegian Red dairy cows in early lactationto compare milk content of phytoestrogens whenfeeding ad libitum white clover (WCS) or red clover(RCS) grass silages prepared from the second and thirdcut without and with 10 kg/d supplementation of a standardconcentrate. The cows were offered either RCS orWCS for 88 d (period 1) and thereafter a mixed redclover-white clover-grass silage for 48 d (period 2). Totaldry matter intake and milk yield were not affected byforage type but increased with concentrate supplementation.Intake of isoflavones was several times greaterin RCS than in WCS, whereas intake of lignans wasgreater in WCS. Concentrate supplementation reducedthe intake of most phytoestrogens. Compared withWCS, RCS diets yielded milk with a greater content offlavonoids, whereas milk from WCS diets had greatercontents of the mammalian lignans enterodiol and enterolactone.The content of the isoflavan equol was particularlyhigh in RCS diets. There was no apparentcarryover effect of clover type on milk phytoestrogencontent because there was no difference in content betweenthe silage treatments 3 wk after the cows weretransferred to the same silage diet (period 2). Concentratesupplementation reduced the milk contents of theflavonoids equol, biochanin A, and daidzein and increasedthe content of mammalian lignans. The effectsof silage type and concentrate supplementation on milkcontents of the individual phytoestrogens were relatedto the intake of the compound or its precursor, exceptfor the effect of concentrate on mammalian lignans,for which the intake of the known precursors was alsoreduced. Overall, this study shows that feeding cowswith silage containing red clover increases the milkcontent of flavonoids at both low and high concentrateReceived November 13, 2007.Accepted March 3, 2008.1Corresponding author: havard.steinshamn@bioforsk.no2715supplementation levels, and decreases the content ofnonflavonoids such as mammalian lignans, when comparedwith silage containing white clover. The increasedcontent of phytoestrogens in milk may be importantwhen the health benefits of milk are studied.Key words: clover species, concentrate level, milk phytoestrogencontent, equol
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