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Thirty-two cows (Black-and-White x HF) in the first 100 days of lactation were divided into 4 groups and fed rations composed of equal proportions of roughages and concentrates in amount of 1 kg per 2 kg of milk at yield exceeding 12 kg/day. The concentrates were supplemented with vitamin E (group I, 336 mg; groups II, III, and IV, 672 mg/cow/day) and selenium: group I, no supplementation; group II, 4 mg/cow/day as sodium selenite; group III, 4 mg/cow/day as selenium yeast; group IV, 2 mg/cow/day as selenium yeast.Cows fed selenium-supplemented rations had significantly elevated serum selenium concentrations (group 1,0.0214 mcg/ml; II-0.0453 mcg/ml; III, 0.0654 mcg/ml; IV, 0.0573 mcg/ml). Selenium from yeast was utilized better than sodium selenite. Regardless of the source of selenium, Se lowered serum a-tocopherol (0.245 vs 0.229; 0.187; 0,232 mg/dl) and retinol (35.57 vs 31.46; 32.25; 29.29 mcg/dl) levels. The addition of selenium when the vitamin E content of the ration was increased modified the lipid metabolism of cows (elevated HDL and triglycerides).

The effects of different feed additives (flavomycin, oregano, MOS and Lactobacillus plantarum) added to diets for growing pigs (20 kg BW) on nutrient digestibility and the microbial status of faeces were investigated in the study.Diet supplementation with different feed additives had no effect on the digestibility of most nutrients. Faecal bacterial populations (E. coli, Lactobacilli spp.) were not affected by diet composition. Diets supplemented with oregano, MOS and L. plantarum did not increase the activity of microbial enzymes or the concentration of short-chain fatty acids in the faeces of pigs.

Amino acid composition, in situ ruminal degradation and intestinal digestion of dry matter (DM), crude protein (CP) and individual amino acids (AA) of fresh and ensiled galega (Galega orientalis Lam.) were determined and their nutritional value calculated according to INRA (1988). Total AA (Trp excluded) in forage (1 st cut, budding) was 81.3 g/16 g N, decreasing to 71.3 g/16 g N in wilted silage + Kemisile 2000 (4 l/ton). The in situ degradation coefficients (k=0.06) for CP and DM in galega forage were higher than in silage (69.5 and 64.4 vs 56.4 and 45.1%); similar relationships were found for total AA degradation after 16 h incubation in the rumen (87.4 vs 66.9%). The mobile nylon bag intestinal digestibility of CP, total AA and DM in wilted silage vs forage was 61.5 and 68.2; 71.6 and 74.2; 21.1 and 23.5%, respectively. The content of PDIA, PDIN and PDIE in galega fodder was slightly higher than in lucerne forage and silage; the energy values were close.

Four high-yielding lactating Holstein cows fitted with duodenal cannulas were used in the experiment. Cows were divided into 2 groups -control (Control) with leucine deficiency and experimental (Leucine) with a leucine supplement. The experiment was divided into 4 periods of 7 days, each consisting of a 3-day preliminary period followed by a 4-day experimental period. In the first period, 2 cows were assigned to Control and the remaining 2 to Leucine. In the subsequent period the cows were switched to the other treatment. Cows were fed individually twice daily the basal diet based on maize silage, lucerne hay and supplemental mixture. Infusions of amino acids in Leucine consisted of methionine (12.6 g/day), lysine (20.7 g/day), histidine (10.7 g/day) and leucine (19.3 g/day). The composition of amino acid infusate in Control was the same except for leucine that was replaced with monosodium L-glutamate. The intake of dry matter was not affected by the treatment (P > 0.05). No effect of leucine infusion on milk yield and composition was observed (P > 0.05), nevertheless the concentration of protein and casein in milk tended to be higher in Leucine (38.3 and 31.3 g/kg) than in Control (37.4 and 30.4 g/kg, respectively, P < 0.1). The yield of milk components was not affected by the treatment (P > 0.05). Duodenal infusion of leucine resulted in a decreased plasma level of isoleucine in Leucine compared to Control (P < 0.01). Concentrations of leucine, cysteine and citrulline tended to be higher and the concentration of tyrosine tended to be lower in Leucine in comparison with Control (P < 0.10).