Authors : L. Garcia Compean, M. Itza Ortiz, J.P. Ramon Ugalde, J.R. Sangines Garcia, B. Ortiz de la Rosa, R. Zamora-Bustillos, A. Reyes Ramirez and H. Magana-Sevilla
Abstract: The objective of the present research was to evaluate a vaccine against E. coli in laying hens in tropical climates and its response to heat stress challenge. About 47880 Bovans White laying hens were assigned at two treatments: 24.806 were vaccinated (sprayed) against Escherichia coli and 23 074, the control treatment were not vaccinated. Two applications were made during breeding, the day 1 and week 12. At 16 weeks were transferred form the breeding farm to the layer farm and were distributed at random in a layer house and identified. The daily mortality in both treatments was recorded. A t-test is performed to determine differences between daily mortality rates, differences were found for the three stages: 16-23 weeks (p<0.05) (0.05+0.04 vs 0.08+0.12) from 23-1 to 34 (p<0.0001) (0.04+0.02 vs 0.07+0.03) and 34-1 to 46-2 (p<0.0001) (0.04+0.01 vs. 0.08+0.04). Mortalities in this flock were 14.384% for unvaccinated and 8.224% in vaccinated. Regression analysis were performed for cumulative mortalities before and after a heat stress event, finding that the trend lines have different slopes for birds vaccinated and unvaccinated before and after the event. Vaccination against E. coli showed a lower mortality in the study conditions and a relation whit heat stress event.
L. Garcia Compean, M. Itza Ortiz, J.P. Ramon Ugalde, J.R. Sangines Garcia, B. Ortiz de la Rosa, R. Zamora-Bustillos, A. Reyes Ramirez and H. Magana-Sevilla, 2011. Escherichia coli Vaccine and Laying Hens Mortality After A Heat Stress Challenge in Tropical Climate. Journal of Animal and Veterinary Advances, 10: 96-99.