Biotechnological aspects of transformation of heavy metal salts and their detoxication in milk of milk cows

Abstract

Based on the results of previous studies on pigs and poultry, in which encouraging results of a significant decrease in the concentration of heavy metals in the body were obtained, respectively, in pork, poultry and eggs, the study provided for the use of the bentonite clay of the Zamankul deposit (RNO-Alania) as an enterosorbent in relation to heavy metals and detoxification of the organism of dairy cows. In order to study the feasibility of using bentonite as an enterosorbent, studies were performed on dairy cows of the Simmental breed in the Kaloyev farm located in st. Zmeyskaya, Kirovsky district of North Ossetia-Alania. To conduct research on the principle of analog pairs, two experimental groups of cows (control and experimental, five cows in each group) of the 3rd and 4th lactation were formed. The experiment lasted for 305 days of lactation from March 2018 to January 2019. Herewith, the control group of cows was fed with a basic diet balanced in all nutritional elements, the experimental livestock, together with the main diet, daily in the composition of the concentrates was injected with crushed bentonite with a particle diameter of 4-6 mm based on the dry matter of the feed (137 g/animal). The study of the concentration of heavy metals (cadmium, lead and zinc) in soil, feed, blood and milk was performed in two periods of lactation (on the 250th and 300th days of lactation). Herewith, an increased content of heavy metals in the soil was established, relative to the MPL: cadmium - 10.1; lead - 7.4; zinc - 9.7 times more, in drinking water: cadmium - 2.5 times; lead - 9.0 times and zinc - 9.7 times more, in feed: cadmium - from 1.7 to 5.3 times; lead - from 1.1 to 1.7; zinc - from 1.0 to 2.5 times the MPL. The inclusion of bentonite to the ration of the animals of the experimental group, in comparison with the control group, in both study periods (250 and 300 days of lactation) contributed to a significant decrease in the concentration of the studied heavy metals in the blood from 17 to 20%, in milk - from 16 to 18 %. The transformation ration values of heavy metals from feed into the body, respectively, into milk, were also lower in the animals of the experimental group, relative to the control.