Poultry veterinarians managing commercial flocks are epidemiologists of sorts. We have to come up with a population diagnosis based on sampling of subsets.
In poultry production, the most common sampling would include routine necropsy sessions conducted for mid-flock analysis. Typically five to six broilers are gathered from various farms at strategic ages ranging from young to market age. For a processor marketing 1 million birds per week, each five- to six-bird sample can represent 2 to 3 harvest days, or from 400,000 to 600,000 individuals! You don’t need to be a statistician to see there is no way that routine necropsy sessions can adequately reflect the health status of so many other birds. I became painfully aware of this shortcoming recently while assessing flock health during a period of worse-than-expected broiler performance. “Normal” birds brought to necropsy sessions all had coccidial lesions but at a level that was seasonally acceptable. None had excessive amounts of parasitism.Read more