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.

The aim of this study was to determine the degradation of dietary isoflavones in rumen fluid under 2 feeding regimens. The experiments were performed in vitro using a rumen fluid buffer system. The rumen fluid was taken from cows fed either a hay diet or a concentrate-rich diet (the diet consisted of 34.6% maize silage, 17.6% haylage, 12.8% alfalfa hay, and 35.0% supplemental mixture on a dry matter basis). As a source of isoflavones, 40% soybean extract (Biomedica, Prague, Czech Republic) at levels of 5, 25, 50, and 75 mg per 40 mL of rumen fluid was used. Samples of soybean extract were incubated in triplicate at 39°C for 0, 3.0, 6.0, 12.0, and 24.0 h in incubation solution. The metabolism of daidzein and genistein was faster under concentrate-rich diet conditions. In general, production of equol started after 3 to 6 h of incubation and reached the highest rate after approximately 12 h of incubation regardless of the type of diet or concentration of extract. In most of the experiments, production of equol continued after 24 h of incubation. Generally, equol production was greater under the hay diet conditions. Furthermore, experiments with higher amounts of added soybean extract revealed possible inhibitory effects of high levels of isoflavones on the rumen microflora.

The aim of the study was to evaluate the effect of extruded rapeseed cake in diets of dairy cows on changes in milk fatty acid profile and iodine content in milk and on the thyroid gland status. An experiment was carried out on four lactating Holstein cows divided into 2 groups – experimental (R) fed a diet based on extruded rapeseed cake and control (S) fed a diet based on extruded full-fat soya. The experiment was divided into 4 periods of 42 days (21 days of preliminary period and 21 days of experimental period). Samples of milk and blood were taken three times a week during the experimental period. DMI was not affected by the treatment (<i>P</i> > 0.05). Milk yield and 4% FCM were lower in R compared to S (<i>P</i> < 0.05). Percentages of milk fat and protein were higher in R than in S (<i>P</i> < 0.05). The total content of SFA and UFA was not affected by the treatment (<i>P</i> > 0.05). However, the content of MUFA in R was higher (34.71 g/100 g) and the content of PUFA was lower (4.00 g/100 g) than in S (32.14 and 5.54 g/100 g, respectively (<i>P</i> < 0.05). The contents of C18:2 and C18:3 isomers and metabolites in R were lower than in S (<i>P</i> < 0.05). The content of <I>cis</I>-9, <I>trans</I>-11 CLA and <I>trans</I>-10, <I>cis</I>-12 CLA was lower in R (0.71 and 0.016 g/100 g) compared to S (0.97 and 0.022 g/100 g, respectively, <i>P</i> < 0.05). The index of atherogenicity and peroxidisability in R was lower than in S (<i>P</i> < 0.05). The index of desaturation was not affected by the treatment (<i>P</i> > 0.05). The mean daily intake of glucosinolates (Gls) in R was 50.14 mmol and resulted in a significant decrease in iodine concentration in milk in R (196.7 &mu;g/l) in comparison with S (367.0 &mu;g/l, <i>P</i> < 0.05) resulting in the lower daily iodine output in milk in R compared to S (4.4 and 9.2 mg/day, respectively, <i>P</i> < 0.05). Concentrations of T₃ and T₄ in blood plasma were not affected by the treatment (<i>P</i> > 0.05).

The objective of this study was to determine the influence of rumen-protected protein supplemented with the amino acids lysine (Lys), methionine (Met) and histidine (His) added either as a powder or in the form of rumen-protected tablets to the rumen of dairy cows on the yield, composition and technological suitability of milk. The experiment was carried out on three lactating Holstein cows with an average weight of 523 kg fitted with ruminal and duodenal cannulas. The experiment was divided into 4 periods of 14 d (10 d preliminary period and 4 d experimental period). In the first period one cow received the tablets (T) and the other two received the non-tableted mixture (C) with the same composition. In the subsequent period the design was opposite. Cows were fed a diet based on maize silage, lucerne hay and a supplemental mixture. Powder or tablets consisted of purified soya-protein HP 300, Lys, Met and His. Average milk yield in C cows was 16.73 kg and was significantly lower than in T cows (17.8 kg; P<0.05). Protein, fat and lactose contents were unaffected by the treatment. Protein yield was lower (529.5 g/d) in the C than in the T (569.3 g/d; P<0.05) cows. The increase in milk protein yield in T cows was followed closely by progressive increases in casein content (2.46 vs 2.68%). The content of short-and medium-chain fatty acids was higher and the proportion of C18:1, C18:2, C18:3n3 and C20:1 was lower in the C than in the T (P<0.05) animals. The proportion of UFA (both MUFA and PUFA) was increased and that of SFA in milk (P<0.05) was decreased in the T animals. The total SFA:UFA ratio was higher in C compared with T cows (1.89 vs 1.52; P<0.05).

The aim of this study was to determine the effect of soya-protein enriched with amino acids: lysine (Lys), methionine (Met) and histidine (His) added either as a powder or in a form of rumenprotected tablets into rumen of dairy cows on the percentage and yield of casein, changes in the proportion of casein fractions resulting in variations in amino acid profile of milk, casein and noncasein protein. The experiment was carried out on three lactating Holstein cows of average weight of 523 kg fitted with ruminal and duodenal cannulas. The experiment was divided into 4 periods of 14 d (10 d preliminary period and a 4 d experimental period). In the first period one cow received the tablets (T group) and the other two received the non-tableted mixture (C group, control) of the same composition. In the subsequent period the rate of animals was antipodal. Cows were fed on diet based on a maize silage, lucerne hay and a supplemental mixture. Tablets or mixture consisted of purified soya-protein HP 300, Lys, Met and His. The casein content and yield was higher in the group T in comparison to the group C (2.68% and 476.55 g vs 2.46% and 408.43 g; P<0.05). Content of β-and κ-casein was unaffected by the treatment while content of α-casein was lower in the T group (54.10 vs 55.98%; P<0.05). Yield of every casein fraction was significantly higher (P<0.05) in the T group than in the C. The increases in the casein yield resulted in significantly higher (P<0.05) yields of individual amino acids in milk and casein in the T group compared to the control. In the experiment we found out that the concentration of Thr in milk and Thr, Pro and Met in casein was 4 SOYA-PROTEIN WITH LYS, MET, AND HIS -MILK COMPOSITION significantly different (P<0.05) in the T group compared to the C. Duodenal flows of individual amino acids through the duodenum were determined.