Variation in content and composition of phenolic compounds in permanent pastures according to botanical variation.

Phenolic compounds contribute to the micronutrient composition of pasture, which in turn may affect animal product composition. To assess the importance and variations in content of these compounds, the polyphenolic and botanical compositions of 24 permanent pastures located in one lowland and two upland regions were studied at equivalent stages of growth. Phenolic fractions were characterized and quantified using HPLC-PDA-ESI-QToF, and the total content was determined by colorimetry over each whole pasture. A rise in altitude was accompanied by a marked increase in total phenolic content, linked to changes in botanical composition, but did not have any influence on the distribution according to molecular class. For all of the pastures, significantly different patterns due to qualitative and quantitative differences among the 92 separate peaks were observed with 31 compounds identified. The involvement of certain plants in the variations of content and composition in phenolic compounds of pastures was statistically evaluated.

Phospholipid, sphingolipid, and fatty acid compositions of the milk fat globule membrane are modified by diet.

The phospholipid and sphingolipid composition of milk is of considerable interest regarding their nutritional and functional properties. The objective of this article was to determine the lipid composition of the milk fat globule membrane (MFGM) of milk from cows fed a diet rich in polyunsaturated fatty acids. The experiments were performed with 2 groups of 6 cows feeding on (i) maize silage ad libitum (+ grassland hay, mixture of cereals, soyabean meal) or (ii) the maize silage-based diet supplemented with extruded linseed (bringing a lipid proportion of 5% of dry matter). The phospholipid and sphingolipid composition of the MFGM was determined using HPLC/ELSD. The fatty acid (FA) composition of total lipids and phospholipids was determined using GC. As expected, the linseed-supplemented diet decreased the saturated FA and increased the unsaturated FA content in milk fat. MFGM in milk from cows fed the diet rich in polyunsaturated FA resulted in (i) a higher amount of phospholipids (+ 18%), which was related to a smaller size of milk fat globules (ii) an increase of 30% (w/w) of the concentration in sphingomyelin, (iii) a higher content in stearic acid (1.7-fold), unsaturated FA (1.36-fold), and C18:1 trans FA: 7.2 +/- 0.5% (3.7-fold). The MFGM contained a higher concentration of unsaturated FA (C18:1, C18:2, and C18:3) and very long-chain FA (C22:0, C23:0, C24:0, EPA, DHA) compared with total lipids extracted from milk. The technological, sensorial, and nutritional consequences of these changes in the lipid composition of the MFGM induced by dietary manipulation remain to be elucidated.

Tissue distribution of isoflavones in ewes after consumption of red clover silage.

When discovered in the 50's, isoflavones were suspected to provoke infertility syndrome in sheep grazing on clover. Many others effects of these phytoestrogens have been documented afterwards. To determine the distribution of isoflavone metabolites in ewe tissues and look for a link with their physiological impact, two ewes were fed a diet containing 50% red clover silage (variety Pawera) for one month with a daily intake of 157.6 mg/kg bw of total isoflavones. Only aglycones were fed due to the fermentation stage of the silage. At the sacrifice, isoflavone metabolites and aglycones were analyzed in blood, liver, kidney, lung, heart, muscle, ovaries, uterus, mammary glands, suprarenal glands, thymus, aorta, thyroid, pituitary gland, cerebellum, olfactory lobes, and brain hemispheres using HPLC-Coularray and LC-MS-MS. The major compounds recovered in tissues were equol and daidzein, present as glucuronides. Kidney concentrations were 10-fold higher than in other tissues. Penetration in brain was very limited. Reproductive organs contained higher concentrations of isoflavones than heart, muscle, or thymus. Distribution of isoflavones in ewe tissues is unequal and may reflect specific impact in some target tissues.

Selection for nutrients by red deer hinds feeding on a mixed forest edge.

We studied the nutritional behaviour of hinds foraging on a mixed-forest edge by direct observation of their choices at each season and by measuring nutrient concentration in the plants. We compared nutrient concentrations in the observed diets with those in the total available vegetation, and with those of 1,000 randomly simulated diets in which we included only those plants that were actually eaten by the animal. Whether the available or the consumed feeds were used as the basis for comparisons had important consequences due to the presence of conifers and ferns, which were high in soluble sugars but were never eaten by the animals (potentially due to their toxicity). The selected diets were lower in sugars than the total available vegetation in summer, but were actually higher in sugars than the random diets generated from consumed forage species only. Hind diets contained more soluble sugars but not more protein than simulated diets in all seasons. Contrary to our prediction, anti-nutritional compounds (ADL and tannins) were avoided only in winter. Compared to simulated diets, hinds consumed more tannins in spring and summer and more ADL in summer and autumn. We suggest that this was a consequence of selection for soluble sugars, because the preferred plant species, which had high soluble sugar concentrations, also contained a large proportion of the anti-nutritional compounds eaten. In winter, the grass-dominated diets contained more fibre (NDF) and less ADL than the simulated diets, indicating that hinds orient their feeding towards digestible fibres. The switch from a browser to a grazer diet was related to a change in the availability of the nutrients, mainly soluble sugars. In our study, grasses contained more soluble sugars and proteins than deciduous browse during winter. This calls into question the dichotomy usually assumed in the literature between grass and browse in terms of nutrient content.

Isoflavones in several clover species and in milk from goats fed clovers.

Isoflavones that exist in forages such as clover can move in milk, and may have beneficial effects on human health. We measured the isoflavones in subterranean (cv Yarloop, Geraldton, Dinninup and Dwalganup) and red (cv Merviot and Hamua) clovers, grown in a mountain environment, and in the milk of two goats fed a fresh mixture of the four subterranean clovers gathered at flowering stage. Isoflavone glycosides were hydrolysed with an improved beta glycosidase method. Free aglycones (FA) and the hydrolysed glycosides + free aglycones fraction (HF) were analysed by HPLC. In milk, the methanol extracted compounds were deconjugated and similarly analysed. Total HF was highest in Yarloop (19 g kg(-1) dry matter) and was three times lower in Merviot. Formononetin was the major compound (46-64% of total HF). FA varied from 30 to 73% of HF. Milk contained formononetin (50 microg L(-1)), similar amounts of equol and p ethylphenol (about 250 microg L(-1)), and equol like compounds (1120 microg L(-1)). Equol, which has estrogenic activity, and p ethylphenol were produced by biotransformation of formononetin, and biochanin A or genistein, respectively. The modulation of isoflavone amounts in milk and the estimation of their interests for human health warrant further investigation.