The potential of vegetative buffers to reduce dust and respiratory virus transmission from commercial poultry farms

The potential of vegetative barriers to reduce dust and avian respiratory virus transmission from a 6-house commercial laying hen facility was evaluated in 3 trials using a combination spray vaccine for Newcastle disease virus (La Sota strain) and infectious bronchitis virus (Mass-Conn strains) as a model. Before each trial, 7-wk-old specific-pathogen-free chickens were placed in coops downwind of the exhaust fans of each house. Vegetative buffers (VEB) were planted between houses 2, 4, and 6 and their coops. Coops downwind of houses 1, 3, and 5 acted as non-VEB controls (CON). Dust accumulation was measured at all coops during each trial. Tracheal and cloacal swabs and blood samples from specific-pathogen-free birds and vegetation clippings or swabs and dust collection filters were collected to monitor virus transmission from the hen houses to the coops. Dust measures did not differ between VEB and CON coops in any trial. In addition, neither Newcastle disease virus nor infectious bronchitis virus could be detected from the vegetation or filters. Predominantly, no differences in virus spread could be detected between birds in the VEB and CON groups; however, the proportion of infectious bronchitis virus-positive serum samples was significantly greater from birds in the CON than in the VEB group (P = 0.003) at 21 d postvaccination in trial 3. Therefore, birds in the CON group were more accessible than those in the VEB group during virus transmission, and VEB of a significant size and density may have the potential to slow or reduce virus spread, or both, from commercial poultry farms.