Which two diseases are turkeys vulnerable to when raised on previous chicken grounds?

Turkeys are particularly susceptible to sinusitis and blackhead when raised on grounds previously occupied by chickens. This vulnerability is due to the different pathogens that can persist in the environment where chickens have been, which may not affect chickens but can be harmful to turkeys.

Sinusitis, commonly seen in turkeys, can be exacerbated by exposure to various bacteria that may linger in areas where chickens have been raised. Blackhead, caused by the protozoan Histomonas meleagridis, is another disease that thrives in the same environments used by chickens. This disease is particularly concerning because it can impact liver function and overall health in turkeys.

The other options focus on diseases that may not have the same direct correlation with previously occupied chicken grounds, such as avian influenza and salmonella, which can be pathogens of concern broadly but are not specifically linked to the crossover between chickens and turkeys in that context. Similarly, diseases like Newcastle and Marek's, while impactful, are not specifically tied to previous chicken grounds in the same manner. Fowl pox and coccidiosis also do not exhibit the specific environmental persistence that can lead to issues when turkeys are placed in environments where chickens have been housed.