A retrospective analysis to identify the contribution of the breeder on health and performance of broiler chickens

Data on performance and health are routinely collected in the various stages of the broiler production chain. In The Netherlands, routinely collected data are usually stored and solely used by the owner(s), and the various databases are not connected. Connecting databases may however provide insight to improve the quality of the chain. We were interested in the contribution of the parent stock to the performance of the broiler flock, as transgenerational effects have been reported and variation in performance and health between breeder farms and flocks exist. Broiler flock data at depopulation, collected by the slaughter plant (growth, uniformity, rejections, first week and total mortality) and from a national database (antibiotic treatments) were linked to breeder flocks and farms by unique identifiers for the period between 2011-2016.
This resulted in 2174 broiler flock records (at house level). Within these records, 74 broiler farms, 88 breeder farms, and 209 breeder flocks were identified. A mixed model analysis was used to simultaneously estimate effects of season, parent flock age, time, and the variance components that determine the contribution of the chain phase to the broiler performance parameters. Results showed no systematic effects of the breeder farm on the various parameters at broiler level. Systematic effects of breeder flock were relatively small; the largest effect was found on rejections in the broiler flock (estimated contribution to the variance component: 7%). The largest contributions to the variance
component were found for broiler farm: 14% (antibiotic treatment) to 59% (growth index). Also the phase between egg laying at the breeder farm and chick placement at the broiler farm (here called: chick delivery) had a large contribution to the variance component: rejections: 27%, first week mortality: 52%). Negligible effects were found for house at broiler farm and specific breeder-broiler farm combinations. A moderate effect of broiler house within a chick delivery was found. It can be concluded that systematic effects of breeder flock and farm on broiler performance and health could not be found, and that broiler farm and chick delivery had a large contribution on the variation in broiler performance and health. This does not exclude that transgenerational
effects exist, but these may be relatively short lasting, and thus could not be found in the present analysis, or might be overruled by more influential factors after egg laying at the breeder farm.