Integrated system decoding etiological structure of respiratory diseases cattle on dairy farms

Bovine respiratory diseases are a major cause of economic losses in the production of livestock products. The presented results of researches show that more often respiratory diseases proceed as mixed virus and bacterial infections. Laboratory diagnosis is of great importance for the success of preventive measures. The objective of the study was to investigate etiological structure of bovine respiratory disease in dairy farms and large dairy complexes in 11 regions of Siberia and Kazakhstan on the basis of an integrated approach to the use of serological and molecular genetics method. The studies were conducted in the laboratory of bio-technology, i.e. diagnostic center SFASC RAS in the period from 2006 to 2016 using a PCR-based test for the detection of bovine herpesvirus -1 (BHV-1), bovine viral diarrhea virus (BVDV), and bacteria Mannheimia haemolytica and Pasteurella multocida. Serological studies for detecting antibod-ies to viruses BHV-1 and BVDV were performed in cell culture. The detection rate of pathogens in bio-logical material samples in monovariante was: BHV-1 was 8.8 %, BVDV was 9.5 %, M. haemolyti-ca was 8.1 % and P. multocida was 10.9 %. BHV-1 was identified in 27.3 % of the samples, BVDV was in 28.6 %, P. multocida and M. haemolytica, re-spectively - in 27.3 and 28.1 % of the samples. The studies found out that respiratory disease may be caused by pathogens in monovariant and vari-ous associations, which were identified on average in 53.4 % of the animals. Antibodies to BHV-1 were detected in 62.9 % and to BVDV were in 70.2 % of the animals. Seroconversion to BHV-1 and BVDV was established in the study of paired serum sam-ples from calves in all categories of farms, and cows on farms with intensive livestock farming lev-el. PCR in conjunction with serological studies es-tablished the leading role of viruses BHV and BVDV in the occurrence of bovine respiratory dis-eases.