Ammonotely in a passerine nectarivore: the influence of renal and post-renal modification on nitrogenous waste product excretion.
Level 5 - mechanism / opinion, no new human data
Animal physiological experiment (non-human comparative biology).
PubMed 12042332 · doi:10.1242/jeb.205.12.1735
What was done
Researchers tested the effects of water, electrolyte (salt), and protein intake, as well as ambient temperature, on the composition of nitrogenous waste products (ammonia, urea, and urate) in both ureteral urine and final excreted fluid of Palestine sunbirds (Nectarinia osea).
What was found
The proportion of ammonia in ureteral urine and excreted fluid was unaffected by total water intake, salt intake, or ambient temperature. Protein intake had no effect on nitrogenous waste concentrations in ureteral urine. However, reducing dietary protein intake increased the relative proportion of ammonia in final excreted fluid by lowering urate concentration, producing apparent ammonotely. The abstract reports no numerical values.
Why it matters
This study demonstrates that apparent ammonotely in nectar-feeding birds can occur through post-renal hindgut modification under low protein intake rather than renal shifts triggered by temperature or high water flux.
Limits
The abstract omits the number of birds tested, specific dietary concentrations, and quantitative measurements or error bounds. Findings are derived from a single avian species in a non-human model.
Cited by
- supports Different animal classes excrete excess nitrogenous waste from protein metabolism in distinct forms: fish excrete ammonia, birds excrete uric acid, and mammals excrete urea.