Effects of Ozone (O3) on Survival and Development of Chick Embryos After Gas Exposure In Ovo

Abstract

We investigated the embryotoxicity of ozone (O3), after gas exposure in ovo, to chick embryos of the Lohmann‐Weiss strain. The main aim of the study is to reduce the microbiological content, particularly of Salmonella enteritides on the egg surface by the use of ozone in different concentrations and response times. The aim of our morphological study is to analyse the influence of gas exposure to the embryonal development of chick. Ozone has proved its worth as a disinfectant without the harmful adverse effects of formaldehyde. The chick embryo provides a useful and well‐defined model for analysis of toxicity of chemicals, particularly with regard to an alternative disinfectant: ozone. Embryotoxicity of ozone in developing chick embryos was studied by examining different parameters: deformities and pathohistology of heart, liver, kidney and spleen, weight, length and survival of embryo. After oviposition the eggs were transferred to a chamber filled with ozon‐oxygen‐mixture in a defined concentration (1% ‐ 5.22%). After achievement of the ozone concentration the eggs were incubated over various response times have 20, 30, 60 min or 17 h. After the incubator times of 18, 19 or 20 days we studied the development of the gas exposed embryos and unexposed controls. The organs were fixed in 4% formalin, embedded in paraffin, cut and stained with hematoxylin‐eosin. High ozone concentration over 5% and high response time of 1 hour provided low graded survival rates of 3.3–13.3%. There was significantly increase of the survival rate after decline of ozone concentration and response time of 90–100%. We found also a remarkable decrease of weight and length in fewer surviving gas exposed embryos with high ozone concentration and response time (Fig. 1.), compared with the normal development of gas‐exposed embryos with study of high survival rate (Fig. 2.). We calculated a 60% increase in the survival rate of embryos exposed to high ozone concentration without response time. In low ozone concentration (1.8%) with high response time of 17 hours the survival rate decreased to 10%. We found no signs of deformities and pathohistology of organs in our embryological examination. In conclusion, ozone has a dose‐dependent effect. The response time constitutes an important factor in the survival and growth of chick embryos after exposure to ozone in ovo. image [ High ozone concentration over 5% and high response time of 1 hour result in a low survival rate of 3,3% and the surviving embryo shows a decrease in body weight and length (right) in comparison to the biggest (left) and lowest (middle) unexposed embryo. ] image [ Height comparison between the unexposed controls (both embryos on the left side) with gas exposed embryos (both embryos on the right side) in a study with low ozone concentration of 1% and low response time of 20 minutes. There are no differences in body weight and length between the unexposed and exposed embryos. ]