Conclusions
We found that diet macronutrient content can alter the abundance of some
bacterial taxa in the gut and potentially alter the relationships
between gut microbial communities and physiological responses important
for responding to infection. Additionally, we found that
immune-challenged birds alter feeding behavior by selectively reducing
protein but not fat intake, however this change in feeding behavior did
not correspond with detectable differences in gut microbiota
communities. Contrary to our predictions, heightened infection risk
(being housed near immune-challenged conspecifics) did not alter feeding
behavior, gut microbiota, or immune and endocrine physiology. However,
regardless of treatment, higher fat consumption in these individuals was
associated with lower gut microbial richness and diversity. Our findings
carry implications for host health and epidemiology, as diet-induced
shifts in the microbiome and physiology could shape disease transmission
dynamics through nutritionally driven shifts in host-pathogen
interactions. Future work should explore if reduced protein consumption
during infection is adaptive for hosts in terms of responding to and
overcoming infection, as this could have implications for disease
transmission.