Applied research note: exploring the relationship between first-week mortality and performance after the first week in broiler chickens

Abstract

First-week mortality (FWM) is considered an important indicator of chick quality in broiler production, but its association with later performance is understudied. Data from 1,142 production cycles across 175 farms belonging to an Italian integrator were analyzed to identify links between management factors at the broiler farm and FWM, and explore the association between FWM and mortality after week 1, daily gain, and FCR. Median FWM was 0.95 % and median total mortality was 3.42 %. Factors associated with FWM were year and sex. For each 1 % increase in FWM, mortality after the first week increased by a factor 1.08 (95 % CI: 1.03 – 1.13, p = 0.002), adjusted for year and sex. However, FWM was not associated with daily gain or FCR. These results suggest that early mortality reflects vulnerabilities that persist throughout the production cycle, increasing later mortality without compromising growth performance. Variance in FWM was largely attributable to within-farm variance. Future research could explore how day-old chick quality contributes to both early and late mortality in broilers.