Fulani Ecotype Chicken Genetic Resource under a Pastured Poultry Management System- 3-Survival Analysis and Risk Factors for Mortality

Résumé

The objective of this study was to characterize and quantify risk factors associated with mortality in Fulani ecotype chickens (FEC) during the laying period. Survival analysis and Cox Proportional Hazards regression were used to describe the probability of mortality in two batches of laying FEC hens with body weight at the point of lay (POL) and body weight at mortality evaluated as potential risk factors. Survival function distribution showed that proportional mortality was higher in batch 1 as compared to batch 2 layers (12% vs.6%). Body weight at the POL did not significantly influence mortality in the pooled as well as in the separate analysis for each population of layers. In contrast, body weight at mortality significantly affected probability of mortality in the pooled data and in both populations. The magnitude of influence was higher in batch 2 than 1, with 0.8% vs. 0.4% increase in risk of mortality respectively for batches 1 and 2 hens, with every unit decrease in body weight below the mean (1073.08 g). This may imply that hens in batch 1 were more sensitive to body weight reduction post-POL compared to batch 2 hens. This study has demonstrated that factors causing a reduction in body weight post[1]POL could be risk factors for mortality in laying FEC chickens.