[Chronic 90-day toxicity of apramycin in chickens]

Investigations were carried out on 72 2-day-old broilers, divided into four groups (one control group--27 broilers and 3 experimental groups--15 broilers in each), treated with apramycin sulphate (AS), which was added to the food in concentration 0, 330, 1000 and 1600 mg/kg (corresponding to 0, 50, 150 and 250 mg/kg m.), in the course of 90 days. It was established that dose of 50 mg/kg m. AS does not causes toxic activities. With doses of 50, 150 and 250 mg/kg m. AS causes reduction of the degree of the pseudo-eosinophilic cells and increase of the percentage of leucocytes--in range similar to the physiological variations, contributes to stimulate the growth and the feed conversion. With doses of 150 and 250 mg/kg m. AS causes reduction of the content of haemoglobin and reduction of the number of erythrocytes; causes dystrophic changes in the internal organs.