Alternative and Unconventional Feeds in Dairy Diets and Their Effect on Fatty Acid Profile and Health Properties of Milk Fat.

Milk fat is an important nutritional compound in the human diet. From the health point of view, some fatty acids (FAs), particularly long-chain PUFAs such as EPA and DHA, have been at the forefront of interest due to their antibacterial, antiviral, anti-inflammatory, and anti-tumor properties, which play a positive role in the prevention of cardiovascular diseases (CVD), as well as linoleic and γ-linolenic acids, which play an important role in CVD treatment as essential components of phospholipids in the mitochondria of cell membranes. Thus, the modification of the FA profile-especially an increase in the concentration of polyunsaturated FAs and n-3 FAs in bovine milk fat-is desirable. The most effective way to achieve this goal is via dietary manipulations. The effects of various strategies in dairy nutrition have been thoroughly investigated; however, there are some alternative or unconventional feedstuffs that are often used for purposes other than basic feeding or modifying the fatty acid profiles of milk, such as tanniferous plants, herbs and spices, and algae. The use of these foods in dairy diets and their effects on milk fatty acid profile are reviewed in this article. The contents of selected individual FAs (atherogenic, rumenic, linoleic, α-linolenic, eicosapentaenoic, and docosahexaenoic acids) and their combinations; the contents of n3 and n6 FAs; n6/n3 ratios; and atherogenic, health-promoting and S/P indices were used as criteria for assessing the effect of these feeds on the health properties of milk fat.

Isoflavones.

Phytoestrogens are naturally occurring nonsteroidal phenolic plant compounds that, due to their molecular structure and size, resemble vertebrate steroids estrogens. This review is focused on plant flavonoids isoflavones, which are ranked among the most estrogenic compounds. The main dietary sources of isoflavones for humans are soybean and soybean products, which contain mainly daidzein and genistein. When they are consumed, they exert estrogenic and/or antiestrogenic effects. Isoflavones are considered chemoprotective and can be used as an alternative therapy for a wide range of hormonal disorders, including several cancer types, namely breast cancer and prostate cancer, cardiovascular diseases, osteoporosis, or menopausal symptoms. On the other hand, isoflavones may also be considered endocrine disruptors with possible negative influences on the state of health in a certain part of the population or on the environment. This review deals with isoflavone classification, structure, and occurrence, with their metabolism, biological, and health effects in humans and animals, and with their utilization and potential risks.

Effects of Isoflavone-Enriched Feed on the Rumen Microbiota in Dairy Cows.

In this study, we compared the effects of two diets containing different isoflavone concentrations on the isoflavone transfer from feed into milk and on the rumen microbiota in lactating dairy cows. The on-farm experiment was conducted on twelve lactating Czech Fleckvieh x Holstein cows divided into two groups, each with similar mean milk yield. Twice daily, cows were individually fed a diet based on maize silage, meadow hay and supplemental mixture. Control group (CTRL) received the basal diet while the experimental group (EXP) received the basal diet supplemented with 40% soybean isoflavone extract. The average daily isoflavone intake in the EXP group (16 g/day) was twice as high as that in the CTRL group (8.4 g/day, P<0.001). Total isoflavone concentrations in milk from the CTRL and EXP groups were 96.89 and 276.07 µg/L, respectively (P<0.001). Equol concentrations in milk increased from 77.78 µg/L in the CTRL group to 186.30 µg/L in the EXP group (P<0.001). The V3-4 region of bacterial 16S rRNA genes was used for metagenomic analysis of the rumen microbiome. The experimental cows exhibited fewer OTUs at a distance level of 0.03 compared to control cows (P<0.05) and reduced microbial richness compared to control cows based on the calculated Inverse Simpson and Shannon indices. Non-metric multidimensional scaling analysis showed that the major contributor to separation between the experimental and control groups were changes in the representation of bacteria belonging to the phyla Bacteroidetes, Proteobacteria, Firmicutes, and Planctomycetes. Surprisingly, a statistically significant positive correlation was found only between isoflavones and the phyla Burkholderiales (r = 0.65, P<0.05) and unclassified Betaproteobacteria (r = 0.58, P<0.05). Previous mouse and human studies of isoflavone effects on the composition of gastrointestinal microbial populations generally report similar findings.