Objective evaluation of the immunogenic effectiveness of polyvalent vaccines against enteral infections of newborn calves under enzootic conditions

: For evaluating the protective effect of polyvalent vaccine against diarrhoea in new born calves caused by rotaviruses, coronaviruses and enterotoxigenic E. coli the method was selected of mathematical and statistical analysis of the set of data characterizing the most important clinical symptoms of the disease during the first three weeks after birth. In two large-scale breeds with a mass occurrence of diarrhoea of the known etiology the state of health of calves before the vaccine application was compared with the state of health of calves born in the period after the vaccination. The following traits were selected for evaluating the severity of the disease: the age of calf at the beginning of the disease, character and intensity of diarrhoea, length of disease and results of treatment. In all the selected indicators, statistically significant differences were determined pointing to the fact that the vaccine used for increasing the immunity against enteropathogenic viruses and bacteria, applied in high pregnant cows and heifers before parturition, protected the sucking calves and calves fed the milk of their mothers against the disease in the first week after birth. The diarrhoea, occurring in the calves of the vaccinated cows and heifers mostly during the second week of age was easy to treat therapeutically and ended in most cases after a short period of a tea diet. After the vaccination, the death loss in both localities decreased more than eight times.