INVESTIGATIONS ON THE ANTIBACTERIAL EFFECT OF CONIFER NEEDLE OILS ON BACTERIA ISOLATED FROM THE FECES OF CAPTIVE CAPERCAILLIES (TETRAO-UROGALLUS L, 1758)

In winter, free-living Capercaillies feed almost exclusively upon need les of various conifer species. An important part of the energy and pr otein requirements of captive Capercaillies, however, is supplied by f ood rich in starch and proteins. The fecal flora of captive Capercaill ies is considerably different from the flora of free-living Capercaill ies. Bacterial diseases are frequent in captivity. The aim of the pres ent study is to determine whether the essential oils from conifer need les possess antibacterial properties against several bacteria, some of which are facultatively pathogenic for Capercaillies. Needles of Pinu s sylvestris contain few tannins, which could be a reason for the Cape rcaillies' preference for these needles. The needles of Abies alba con tain high amounts of tannins and essential oils, which could explain t he refusal of Capercaillies to eat these needles. The antibacterial ef fect of commercially available essential oils on the bacteria is inves tigated with a filter paper disc method and in a liquid medium. The es sential oils possess a bacteriostatic or a bactericidal effect against some of the tested bacteria. Feeding on natural forage plants may hel p prevent the colonization of the intestines by facultatively pathogen ic bacteria. The authors discuss why Capercaillies, especially young b irds that are to be released, should be fed with natural forage plants .