Evaluation of the efficacy of Broilact® in preventing infection of broiler chicks with Salmonella enteritidis PT4

Abstract A study was conducted to evaluate treatment of day-old broiler chicks with Broilact ® , a live-culture preparation, for preventing intestinal colonization by a non-host-specific Salmonella ( S. enteriditis PT4, with high resistance to nalidixic acid). Newly hatched broiler chicks were sprayed with Broilact ® at a commercial hatchery and delivered on the same day to Huntingdon Research Centre. Control chicks from the same source (i.e. chicks not treated with Broilact ® ) were sent separately. Chicks were maintained in floor pens in groups of 40. The challenge was introduced by means of seeder birds infected with S. enteritidis PT4 (nal ® ) at a nominal dose level of 10 4 CFU per bird (3 seeder birds per pen of 40 contact birds). Groups of birds were killed 7, 28 and 40 days after challenge, and in each case caecal contents were examined culturally for the test organism. A total of 18 deaths occured including 13 untreated contact birds, 3 Broilect ® -treated contact birds and 2 seeder birds. These were attributed to the experimental infection. Results of the examination of caecal contents from untreated control birds indicated that the challenge organism was successfully established in contact chicks via the seeder birds. The overall results for birds treated with Broiler ® showed a clear protective effect, with little indication of any significant infection by the challenge organism. It was concluded therefore that under the conditions of this study, Broiler ® was largely effective in preventing intestinal colonization by the non-host-specific S. enteritidis PT4.