Bacteriophages to Control in Commercially Farmed Broiler Chickens, in Australia.

This study describes the development and use of bacteriophage cocktails to control in broiler chickens, in a commercial setting, in Queensland Australia, following the birds from farm to the processing plant. The components of the bacteriophage cocktails were selected to be effective against the maximum number of and isolates encountered on SE Queensland farms. Farms were identified that had suitable target populations and phage were undetectable 1 week prior to the intended treatment. Cocktails of phages were administered at 47 days of age. Groups of study birds were slaughtered the following day, on-farm, at the end of flock transport to the plant, and at processing (approximately 28 h post-treatment). On Farm A, the phage treatment significantly reduced levels in the ceca at the farm in the range of 1-3 log CFU/g ( = 0.007), compared to mock treated controls. However, individual birds sampled on farm (1/10) or following transport (2/10) exhibited high cecal counts with low phage titers, suggesting that treatment periods > 24 h may be required to ensure phage replication for effective biocontrol . At the time of the trial the control birds in Farm B were phage positive despite having been negative one week earlier. There was no significant difference in the cecal counts between the treatment and control groups following treatment but a fall of 1.7 log CFU/g was observed from that determined from birds collected the previous week ( = 0.0004). isolates from both farms retained sensitivity to the treatment phages. These trials demonstrated bacteriophages sourced from Queensland farms have the potential to reduce intestinal levels in market ready broiler chickens.