Immunomodulatory and antimicrobial effects of selected herbs on laying hens

The aim of the study was to investigate the efficiency of feed supplementation with dried calendula (C. officinalis), dandelion (T. officinale) and marigold (T. erecta) flowers, as well as dried basil (O. basilicum 'Genovese') leaves on the kinetics of the total leukocytes, helper and cytotoxic T lymphocytes, and B lymphocytes in peripheral blood, as well as on intestinal excretion of Escherichia coli in laying hens. Laying hens of Tetra SL line, aged 25 weeks, were used in the study. The animals were divided into nine groups of 15 birds. The laying hens were fed common feed with the addition of 1% (10 g/kg) and 3% (30 g/kg) chopped flowers or leaves of the above mentioned herbs. The immunomodulatory and antimicrobial effects of medicinal herbs in laying hens were estimated by the above mentioned parameters determined at the beginning of the experiment and on day 14 and day 28 of the study, i.e. at the birds' ages of 25, 27 and 29 weeks. The study results showed that the addition of chopped calendula and dandelion flowers to laying hen feed stimulated proliferation of total leukocytes as well as T and B lymphocytes, particularly in the groups receiving 3% chopped herbs (P<0.01). All study herbs were found to have antimicrobial activity. The results obtained definitely confirm the favorable impact of adding herbs to hen feed because of their antimicrobial and immunostimulatory effects. Phytogenic feed additives exert favourable effects, however, knowledge of their use in poultry feed is still inadequate, thus requiring additional research. It was concluded that phytobiotics might be combined with other feed additives such as probiotics or prebiotics, in order to attain better results in poultry production.