Ludmila Křížová

The effect of feeding soybean-derived phytoestogens on their concentration in plasma and milk of lactating dairy cows

The objective of this study was to determine the effect of dietary soybean phytoestrogens, daidzein and genistein, on yield and composition of milk and excretion of phytoestrogens and their metabolites into milk. The experiment was carried out on four lactating Holstein cows as replicated Latin square in a double reversal design. The experiment was divided into four periods of 42 days consisting of a 21-day preliminary period and a 21-day experimental period. Cows were divided into two groups. The control group (Group R) was fed a diet based on extruded rapeseed cake while the experimental group (Group S) received a diet containing extruded full-fat soybeans. Compared to Group R, in Group S the daily intake of daidzein and genistein was about 40 and 75 times higher, respectively. In the milk of Group S the concentration of daidzein and its metabolite equol was significantly higher (p < 0.001) and the concentration of genistein tended to be higher than in Group R. Total excretion of daidzein, genistein and equol in milk of Group S, being 384, 958 and 1300 μg/d, respectively, was higher than in Group R (285, 794 and 80 μg/d, respectively, p < 0.001). In Group S the concentration of daidzein, genistein and equol in plasma was also increased (p < 0.001).

The Effect of Technological Processing on the Content of Isoflavones in Bovine Milk and Dairy Products

Isoflavones that belong to a class of phytoestrogens have a relatively limited distribution in nature and from the aspects of human nutrition they are found in physiologically relevant amounts only in soybeans and soybean-derived foods (Franke et al., 1998). Isoflavones are phytoalexins that are formed by the host plant in response to physiological or biological stimuli and possess properties (i.e. antifungal, antimicrobial, and antioxidant) that enhance the survival of the soybean (Dakora & Phillips, 1996). For this reason, soybean isoflavone concentrations increase greatly in times of stress (e.g. limited moisture) and are influenced by the environmental conditions under which the soybean is grown (Eldridge & Kwolek, 1983, Wang & Murphy, 1994). The major dietary phytoestrogens present in soya (Glycine max (L.) Merr.) are daidzein, genistein and glycitein. After ingestion these substances are subjected to biotransformation by gut microbiota to diverse metabolites that can be detected in human urine (Joannou et al., 1995, Lampe et al., 1998, Coldham et al., 1999, Rowland et al., 1999, Hur et al., 2000, Heinonen et al., 2003, Zheng et al., 2003, Simons et al., 2005). While glycitein has been found to be metabolically stable (Setchell et al., 2002), genistein is converted to 6’-hydroxy-Odesmethylangolensin, 2,4,6-trihydroxybenzoic acid and p-ethyl phenol (Heinonen et al., 1999, Steer et al., 2003, Wahala et al., 1998), daidzein is metabolised by intestinal microflora to equol and O-desmethylangolensin (Heinonen et al., 1999, Adlercreutz et al., 1986). Especially equol has gained a lot of attention since Setchell et al. (2002) proposed a hypothesis that the ability to biotransform daidzein to equol may be the key factor to clinical effectiveness of soy protein in cardiovascular, bone, and menopausal health in so-called equol producers. Indeed, recent studies found that equol is in vitro more bio-active than its precursor daidzein: it has a higher oestrogenicity (Kostelac et al., 2003, Setchell et al., 2002, Morito et al., 2001, Muthyala et al., 2004, Sathyamoorthy & Wang, 1997, Schmitt et al., 2001), is a more potent anti-oxidant (Arora et al., 1998, Mitchell et al., 1998, Rimbach et al., 2003, Turner et al., 2004) and possesses anti-androgenic properties (Lund et al., 2004). Furthermore, equol has a higher effective free fraction circulating in human serum (Nagel et al., 1999) and a slower plasma clearance (Setchell et al., 2002) compared to daidzein.

Bacterial community dynamics in a rumen fluid bioreactor during in-vitro cultivation.

To study the various processes in the rumen the in vitro techniques are widely used to realize more controlled and reproducible conditions compared to in vivo experiments. Mostly, only the parameters like pH changes, volatile fatty acids content or metabolite production are monitored. In this study we examine the bacterial community dynamics of rumen fluid in course of ten day cultivation realize under standard conditions described in the literature. Whereas the pH values, total VFA content and A/P ratio in bioreactor were consistent with natural conditions in the rumen, the mean redox-potential values of -251 and -243mV were much more negative. For culture-independent assessment of bacterial community composition, the Illumina MiSeq results indicated that the community contained 292 bacterial genera. In course of ten days cultivation a significant changes in the microbial community were measured when Bacteroidetes to Firmicutes ratio changed from 3.2 to 1.2 and phyla Proteobacteria and Actinobacteria represented by genus Bifidobacterium and Olsenella significantly increased. The main responsible factor of these changes seems to be very low redox potential in bioreactor together with accumulation of simple carbohydrates in milieu as a result of limited excretion of fermented feed and absence of nutrient absorbing mechanisms.

The effect of cattle breed, season and type of diet on nitrogen fractions and amino acid profile of raw milk

Abstract. The aim of the study was to describe the differences in nitrogen fractions and deepen the knowledge in the amino acid profile of raw milk affected by the breed of cattle, season and type of feeding. The study was conducted from June 2005 to February 2007 on 64 bulk milk samples collected from eight herds consisting of Czech Fleckvieh (four herds) and Holstein (four herds) breed. One half of the herds of each breed was grazed while the other half was not. Samples were collected twice in winter and twice in summer. The effect of the breed resulted in differences in milk yield that was lower in Czech Fleckvieh (5 385.50 kg) than in Holstein (7 015.15 kg, P P P P P P

Role of Fatty Acids in Milk Fat and the Influence of Selected Factors on Their Variability—A Review

Fatty acids (FAs) of milk fat are considered to be important nutritional components of the diets of a significant portion of the human population and substantially affect human health. With regard to dairy farming, the FA profile is also seen as an important factor in the technological quality of raw milk. In this sense, making targeted modifications to the FA profile has the potential to significantly contribute to the production of dairy products with higher added value. Thus, FAs also have economic importance. Current developments in analytical methods and their increasing efficiency enable the study of FA profiles not only for scientific purposes but also in terms of practical technological applications. It is important to study the sources of variability of FAs in milk, which include population genetics, type of farming, and targeted animal nutrition. It is equally important to study the health and technological impacts of FAs. This review summarizes current knowledge in the field regarding sources of FA variability, including the impact of factors such as: animal nutrition, seasonal feed changes, type of animal farming (conventional and organic), genetic parameters (influence of breed), animal individuality, lactation, and milk yield. Potential practical applications (to improve food technology and consumer health) of FA profile information are also reviewed.

Determination of in vitro isoflavone degradation in rumen fluid

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.

Composition, physiCal and teChnologiCal properties of raw milk as affeCted by Cattle breed, season and type of diet* *

Abstract The aim of the study was to describe the differences in composition, physical and technological properties of raw milk as affected by breed of cattle, season and type of feeding. The study was conducted from June 2005 to February 2007 on bulk milk samples (BMS) collected from 8 commercial dairy herds consisting of Czech Fleckvieh (CF, 4 herds) and Holstein (H, 4 herds) dairy cows. Half of herds in each breed was grazing (G) during summer season while the other half was not (N). Samples were collected regularly two times in winter (W) and two times in summer (S) period resulting in a total of 64 bulk milk samples (BMS) examined. Milk yield in CF (5385.50 kg) was lower (P<0.05) than in H (7015.15 kg). Milk fat in CF was higher (P<0.05) than in H breed being 3.9 and 3.72 g/100 g, respectively. CF cows had higher (P<0.05) content of crude protein, casein, true protein and non-protein nitrogen (NPN) than H. Content of fat, crude protein, casein, true protein and whey protein was lower (P<0.05) in summer (S) than in winter (W). Milk yield in grazing herds (G, 5197.50 kg) was lower (P<0.05) than in non-grazing herds (N, 7203.75 kg). Content of fat was higher (P<0.05) in G (3.89 g/100 g) than in N (3.73 g/100 g). Concentration of lactose, urea, crude protein, casein, true protein, whey protein was lower (P<0.05) in G than in N. In conclusion, the Czech Fleckvieh breed had a lower milk yield but produced milk with higher concentration of the main milk components than the Czech population of the Holstein breed. Large seasonal variations were determined in concentrations of the main milk components. The most pronounced changes in milk composition were caused by the type of feeding with a clear decrease in milk yield and content of lactose and all studied protein fractions and higher content of fat in grazing herds compared to non-grazing herds.