MODERN APPROACHES TO THE PREVENTION OF REO-VIRUS BIRD INFECTION
Currently, reo-virus infection causes significant economic damage to industrial poultry worldwide. Losses as a result of the disease consist of: 1) direct losses - death of chickens (5-30 %), increased culling due to lameness, low weight gain (up to 40 %), reduction of carcass categories, reduction of laying by 6-20 %; in breeding farms, a decrease in the sexual activity of poultry is observed, which is the reason for the decrease in fertilization - derivability; 2) indirect losses associated with the cost of eliminating the effects of primary losses, as well as the immune-suppressive effect of reo-viruses, which increase the risk of other infections and inhibit the formation of post-vaccine immunity. Reo-virus has an immune-suppressive effect on the sick bird, which may be the cause of such diseases as small absorption syndrome and syndrome of increased bird death. Small absorption syndrome, which can be caused by reo-virus, is characterized by slowing growth, low feed conversion index and damage to the bones of the bird, which becomes apparent until 2 weeks of age and later. The syndrome of absorption is characterized by an increase in glandular stomach, sometimes with necrosis and signs of catarrhal hemorrhagic enteritis. The incidence is on average 5 to 15 %, but can reach up to 40 %.
In studying the pathogenesis of reo-virus infection, it was found that the intestine is the main target of the virus, regardless of the method of its introduction. After oral or aerogenic infection, the pathogen enters the bloodstream and, as a result of viremia, is rapidly spread to various organs and tissues. In particular, the virus can be isolated from the intestines, bursa of Fabricius, liver, pancreas, heart, kidneys, joints and tendons. When conducting serological studies in ELISA (test system company IDvet, France), the presence of antibodies in the blood of broilers to reo-virus level ranged from 40-52 days in the range from 1125 to 5138 indicates the circulation of the field virus of reo-virus infection. In the study of broiler sera for 2, 3, 7 days, the cultivation of specific antibodies to reo-virus was not detected. Starting from the 14th day, the mean titer of AO to reo-virus was 1989 and their levels ranged from 3478 to 4825 at 21, 28, 35 and 45 days. 2.3 times (35 days) and 45 days 2.4 times.
These data indicate the circulation of a field strain of reo-virus infection. It was inserted that at completion of broiler fattening with reo-virus lesion, body weight was lower than the technological norm by 9.8%. When determining specific BP for reo-virus in sera from different age groups of broilers of 11 batches, including from poultry: 9 batches of non-vaccinated against reo-virus infection and 2 batches of vaccinated poultry have determined the number of BPs in serum among the 9 batches received from the unvaccinated parent stock, there is evidence of field strain circulation. The percentage of specific AOs in 2 batches received from parental herds vaccinated against reo-virus infection ranged from 87.5-100, indicating the effectiveness of the vaccination. To control reo-virus infection, serological monitoring in poultry farms should be carried out.
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