Ractopamine at One Year of Commercial Application 986

Bacteriophage are viruses that can infect and kill bacteria. A study was conducted to determine if bacteriophage added to drinking water for 1 wk prior to respiratory challenge of broiler chickens with E. coli would provide protection. There were 12 treatments with 2 replicate pens of 10 chicks. The treatments consisted of birds on normal water challenged at 1 wk with either 103 or 104 cfu E. coli injected into the thoracic airsac, or with either 103, 106, or 104, 106 phage/ml in their water, respectively. Unchallenged birds were given either 103, 104, or 106 phage/ml in their water, and birds on normal water were unchallenged, challenged with the culture broth, or with phosphate buffered saline. The birds were necropsied at 3 wks of age. At 2 wks, birds challenged with 104 E. coli regardless of water treatment, and birds challenged with 103 E. coli on normal water had decreased BW, however, birds challenged with 103 E. coli and given water treated with either 103 or 106 phage/ml had higher BW than birds challenged with 103 E. coli on normal water. At 3 wks, unchallenged birds that received 103 phage, and birds that received 104 phage and challenged with 104 E. coli had decreased BW. At 1 wk, treatment of water with 106 phage/ml decreased mortality by 50% in birds challenged with 103 E. coli. Total mortality was 55% in the birds that received 104 E. coli alone, 35% when treated with 104 phage, and 40% when treated with 106 phage. These data indicate that treating the water of broiler chickens prior to a respiratory challenge with E. coli may have provided some protection immediately after challenge.