Introduction: The present study aimed to investigate the effect of Enterococcus faecium EF55 on chickens, as well as its influence on proliferative activity of epithelial intestinal cells after infection with Salmonella enterica serovar Enteritidis phage type 4 (SE PT4). Moreover, the length and area of duodenal and jejunal villi of the birds were examined. Material and Methods: A pool of 80 birds was divided randomly into four groups. Probiotic group (EF) and Salmonella + probiotic group (EFSE) received E. faecium EF55 (10 9 CFU -3 g per group/day) during 22 d. Salmonella group (SE) and EFSE group were infected with Salmonella Enteritidis PT4 (10 8 CFU in 0.2 mL PBS) in a single dose per os on day four of the experiment, whereas control birds (C group) received only 0.2 mL of PBS on that day. Samples were taken on the 4 th and 18 th day post infection. Results: Supplementation of feed with E. faecium EF 55 confirmed its selective antibacterial activity against SE PT4. The chickens infected with SE PT4 and fed E. faecium EF55 supplemented diet showed increased proliferative activity of enterocytes in the jejunum in both samplings. Applied probiotic strain demonstrated positive impact on intestinal morphometry in the jejunum of both non-infected groups and in Salmonella-infected chickens. In the latter group, the beneficial effect of E. faecium EF 55 was manifested by more efficient tissue turnover in the jejunum.

The effect of oregano essential oil on growth performance, intestinal alkaline phosphatase (IAP) level, enterocyte proliferative ability, plasma proteins, and plasma minerals (calcium and magnesium) were studied in 1 day-old Ross 308 hybrid broiler chickens under commercial conditions during 42 experiment. Chickens fed oregano oil supplemented diet (0.707 g.kg-1) had significantly higher body weight gain (BWG) in the grower (19-29 d) and finisher (30-42 d) periods. Total plasma immunoglobulin levels were lower while mineral levels were higher during the finisher period. Significant decrease of IAP activity was demonstrated in animals fed oregano oil supplemented diet on 29, and 42 days of the experiment. Proliferative activity of enterocytes significantly increased in the finisher period along duodenal villi in animals treated with essential oil extracted from oregano. We suppose that higher body performance was probably the result of higher digestibility in the digestive tract. It is suggested that the antibacterial effect of carvacrol caused a lower number of intestinal bacteria, decrease of immunoglobulins and increase of investigated plasma proteins

The effects of sage extract on the activity of intestinal alkaline phosphatase (AP), proliferative ability of enterocytes, and growth performance in chickens were studied during 42 days of the experiment under commercial conditions. A significant increase of body weight gain was found in chickens fed with sage extract in the grower period (17-29 days of age) and in the finisher period (30-42 day of age). Total serum proteins were significantly (p < 0.05) increased at 29 days of age in animals treated with sage extract. A significant (p < 0.001) decrease in activity of intestinal AP was demonstrated on 29 and 42 days in animals fed with sage extract complemented diet. Proliferative activity of enterocytes was increased (p < 0.01) in the finisher period along the duodenal villi in animals treated with sage extract. We conclude that the higher growth performance was probably due to improved endogenous secretion of the liver as a consequence of increased total proteins mainly in the grower period. Decreased activity of intestinal alkaline phosphatase was not in correlation with proliferative ability of enterocytes and the lower activity of AP could be influenced by improved digestion of lipids.