[Blood bactericidal activity in calves under various lighting regimes]

Reported in this paper are the effects of varying lighting regimes on serum-bactericide capacity of calves, aged between 3 and 15 weeks. The results, first of all, have shown that the serum-bactericide system is affected by visible light. The reactivity of the complex defence system is reduced by extremely short days, as compared to extremely long days, with the animals being exposed to something between 80 and 100 lx, round the clock. Extremely long days were found to have positive effects on adaptation to changing environmental conditions, but negative effects of other abiotic factors of the environment could not be offset by visible light. Substitution of artificial light for natural light did not bring about any disadvantageous effects upon immunological reactivity of calves, aged between 3 and 15 weeks, under the authors' experimental conditions. Therefore, production in windowless structures is possible without any risk, provided that the fattening animals are kept in a properly controlled artificial light regime.