The objective of the study was to determine the effect of soybean-derived phytoestrogens and their metabolites on the activity of sex hormones during the oestrous cycle in multiparous lactating dairy cows. The experiment was carried out on 4 multiparous lactating Holstein cows in the form of replicated Latin square in double reversal design. The experiment in the total length of 168 days was divided into 4 periods of 42 days, each consisting of a 21-day preliminary period and a 21-day collecting period. Cows were divided into 2 groups of 2 cows. The control group (C) was fed a diet based on extruded rapeseed cake while the experimental group (S) was fed a diet containing extruded full-fat soya. The intake of total isoflavones was 3297 mg/d in S and 58.0 mg/d in C (P < 0.001). The concentrations of individual isoflavones, it is daidzein, genistein and equol in plasma were significantly higher in the experimental group S (49.3, 78.7 and 218.8 ng/ml, respectively) than in the control group C (13.5, 42.9 and 18.3 ng/ml, respectively, P < 0.001). Plasma concentration of progesterone throughout the oestrous cycle was not influenced by the diet used (P > 0.05). Plasma concentration of prostaglandine PGFM throughout the oestrous cycle in the experimental group (S) tended to be higher (P = 0.095) than in the control group (C). No differences in the length of the oestrous cycle between the cows fed different diets were observed.

In this study, laccase (from Trametes versicolor, 8.3 U mgenz−1) was used for the decolorisation of Saturn Blue L4G (10 mg L−1). The efficiency of the decolorisation (ratio between the amount of decolorised dye and initial amount of dye) by a free enzyme was 48 % and the decolorisation rate was determined at 2.11 × 10−3 mgdye mgenz−1 min−1. After immobilisation in lens-shaped poly(vinyl alcohol) hydrogel capsules LentiKats® Biocatalyst (LB) (concentration of immobilised enzyme: 4 mg per g of particles; volume-loading rate of LB: 10 g per 100 mL of medium), the enzyme retained 16.1 % of its original activity (1.34 U mgenz−1). Immobilised laccase was used for the dye decolorisation in 130 repeated batch tests with 71 % efficiency (LB activity: 7 × 10−3 mgdye min−1 gLB−1). In continuous mode (after 716.5 h), the efficiency of the dye decolorisation was 48 % (LB activity: 3.3 × 10−4 mgdye min/−1 gLB−1).

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