Development of methods for prevention of cryptosporidiosis of calves

Cryptosporidiosis of calves, caused by the parasite Cryptosporidium parvum, is a dangerous disease for calves for up to one month. Sick animals suffer from debilitating diarrhea, intoxication, and dehydration, which can lead to death. Currently, effective preventive and curative measures have not been developed. Therefore, new strategies for preventing cryptosporidiosis in cattle are being sought. The study was conducted on the farm for raising young cattle in Holstein LTD agricultural firm “Lan” Sumy region in February 2021. The circulating microflora in the calf and the clinical condition of the animals were determined. The first experimental group of calves used the antimicrobial agent Trimeratinvet powder (water-soluble powder for oral administration). In the second experimental group, calves were fed the acidifier Kronocid L. As a control, healthy calves were used, which received a regular diet. Conducted a study of fecal masses of calves from birth to one month. The presence of Cryptosporidium spp. in fecal masses of calves was determined microscopically and by nested polymerase chain reaction. The count of microorganisms was performed after cultivation on elective media and determined the number of colony-forming units in CFU/cm3. The EXPERTISTM Rainbow diagnostic kit was used to diagnose Rotavirus and Coronavirus. Studies have shown that Cryptosporidium in calves under one month of age is the most common cause of diarrhea (42 %). Acidifier Kronocid L and Trimeratinvet inhibited the reproduction of cryptosporidia by stopping sporulation. Acidifier at a pH of 4.5 penetrated the oocyst's shell, causing cytoplasm compression. At 60 minutes of exposure, Kronocid L reduced the possibility of sporulation and destroyed 90 % of treated oocysts, which is 20 % more than the antimicrobial agent Trimeratinvet. In the experimental group using Trimeratinvet, the onset of chewing occurred later than eight days compared to the control group and with Kronocid L. Calves of the experimental groups had an average weight gain during the month with Trimeratinvet less by 20.8 % (P ≤ 0.05), with Kronocid L – by 14.3 % compared to healthy. Prospects for further research are to determine the effect of Cronocid L and other species of Cryptosporidium in adult cattle.