The study with sage (Salvia officinalis L.) cv. ‘Bona’ was conducted in the years 1997–1999. The effect of time of harvest on yield of fresh herb sage and yield of air dry herb, yield of air dry leaves sage. The experiment was conducted with sage two-year old. Sage transplants were planted in distance 30×40 cm. The plant material was harvested twice – in May and in September. Harvest date hat significant influence on the weight of fresh sage herb. Yield of fresh sage herb in September was bigger (190.2 dt ha⁻¹) than yield of fresh sage herb in May (104.7 dt ha⁻¹). The percentage quantity of the essential oil in the herb and leaves of sage was depended on the harvest date. The herb and leaves of sage in September had bigger the percentage quantity of the essential oil than in May. The percentage quantity of the essential oil in the leaves of sage, witch was collected in September amounted above 1.5%.
Plant essential oils and their active components have shown a large scale of activities: as antimicrobials, anti-oxidants, digestive stimulators, anti-inflammators, appetisers and performance enhancers. The antimicrobial properties of the essential oil from sage (Salvia officinalis L., family Lamiaceae) were evaluated against selected bacteria in a model experiment in crossbred piglets (Slovak White x Pietrain) weaned at 10 days of age. The essential oil was applied daily in a dose of 0.05% into the commercial feed mixture ČOS 1 and ČOS 2 for a period of three weeks, starting at the age of 21 days to 7 piglets in an experimental group and pathogen concentrations were compared with a control group of 3 piglets. Faecal samples of piglets were analyzed on the 21st, 35th and 42nd days of age and counts of anaerobes, Escherichia coli, enterobacteria and enterococci were performed. The differences in counts of selected bacteria within the control group during the experiment were not statistically significant. The counts within the experimental group showed statistically significant differences (p<0.05) in number of all selected bacteria between 1st and 2nd samplings. The anaerobic bacteria count was also significantly different on 21st and 42nd day of age. Comparing the control and the experimental group counts of Escherichia coli at the age of 35 days were significantly lower in the experimental group. All statistically significant differences observed showed decrease in selected bacteria counts. No adverse effects on animal health were noticed when using sage essential oil. Therefore, sage oil may be recommended to be an alternative fytoaditive antimicrobial supplement to conventional additives used in animal feed. (Because of the essential oil is inhibitory to selected pathogenic microorganisms it may provide alternative and supplement to conventional antimicrobial additives in foods.)