Determination of the level of safety of Humilid during biotesting at ciliates

. The «Humilide» – Biologically Active Feed Supplement is a 10 % solution of humic acids that, by its antioxidant, immunostimulatory and antimicrobial properties, affects feed conversion, productivity and meat quality of farm animals. It is made according to TU In 15.7-00493675 004: 2009 in the conditions of the Research Laboratory of Humic Substances named of prof. L. A. Khristeva. Most of the work on the effects of the supplement has been done on poultry of different species and pigs. The available data on the safety of the feed additive «Humilide» were analyzed and biotested on Paramecium caudatum in accordance with the requirements of the current legislation in the field of control of veterinary preparations and feed additives. A series of Humilide dilutions of 0.1–100 g/l on the culture medium at ciliates were prepared for toxicological studies. Acute toxicity data of the tested concentrations were obtained according to the recommended methods of rapid bioassay. LC 50 values were determined by probit analysis of lethality curves. In solutions of «Humilide» 1.0 and 10 g/l within 1 hour of observation, the death of the protozoa was less than 10 % of the total number. A concentration of 100 g/l causes a decrease their quantity. According to the calculation of the toxicity of «Humilide» by the method of Bliss & Prozorovsky LC 50 for Paramecium caudatum is 104 g / l. Using the graphical method for calculating LC 50 from the obtained regression line, the result was 124 g/l. Thus, «Humilide» at a concentration of less than 1 % is non-toxic to protozoa, NOEC (No Observed Effect Concentration) is 2 g/l and EC 50 (Half maximal effective concentration) is 104–124 g/l. Therefore, the results on the activity of «Humilide» in relation to the Paramecium caudatum allow to classify it as a non-toxic substance, LC 50 – over 5 000 mg/kg. It is IV class acute toxicity according to SP 8.8.1.2.002-98 (Ukraine) and international criteria – 5 toxicity category. When converted to the content of humic acids in the composition of the sample, this corresponds to 10.4–12.4 g/l.