The influence of essential oils (EOs) from medicinal and aromatic plants from sage (SA), cinnamon (CN), thyme (TH) and oregano (OR) on the amylolytic, proteolytic and cellulolytic activities in chyme of the duodenum (DU), the small (SI) and large intestine (LI), the caecum (CE) and the rectum (RE) as well as on the growth ability of laboratory ICR outbred mice were compared in four feeding trials. The negative control was present in the each trial. EOs were mixed into a feed mixture (crude protein (CP) 170.0, fibre 115.0, fat 27.0, lysine 7.0, methionine and cystine 6.7, Ca 9.0, P 6.0 g.kg-1 dry matter (DM), metabolic energy (ME) 10 MJ.kg-1 DM) of experimental group as follows: 1) 6 groups (n=36, age 63 days, period 14 days) SA, CN, TH, OR, the blend of SA with OR, the dosages of EOs 0.42 except OR 0.21 ml.100 g-1 feed, 2) 2 groups (n=12, age 28 days, period 30 days) blend of SA 0.42 with OR 0.21 ml.100 g-1 feed, 3)
3 groups (n=18, age 28 days, period 58 days) CN and TH, both 0.5 ml.100 g-1 feed, 4) 2 groups (n=12, age 28 days, period 8 days) the blend of CN with TH 0.42 ml.100 g-1 feed. The peroral intake of blend of EOs from OR with SA increased the weight gains by 25 %. Additionally, it stimulated the activities of digestive enzymes in the chyme of intestinal apparatus of laboratory mice in the experimental group compared to control as follows: amylolytic by 4,138 μmol.s-1.g-1 and proteolytic by 282.2 mg azoalbumin.min-1.g-1 in SI (p<0.01), cellulolytic by 23.58 in LI and by 34.87 mmol glucose.min-1.g-1 in CE (p<0.01).