Nitrate balance and biosynthesis in the ferret

Abstract

The net biosynthesis of nitrate in the ferret was demonstrated to be 8.89 to 10.3 μmol/kg bw/day. Nitrate balance studies indicated that, because of metabolism, excretion of nitrate was lower than ingestion when oral doses were higher than 6.3 μmol/day. At nitrate ingestion levels of less than 6.3 mot/day, excretion exceeded intake. Studies with 15N-labeled nitrate indicated that only 36% of the oral dose was recoverable as [ 15N]nitrate from urine. Oral doses of 15N-labeled ammonia resulted in the incorporation of the 15N label into nitrate in urine and feces. This demonstrates that ammonia can serve as a precursor to biosynthesized nitrate. An increase in nitrate excretion was seen when animals were treated with neomycin sulfate and mycostatin to reduce gut microflora populations. This increase was as large as 200%. Short-term studies indicated that dietary protein quality had little effect on nitrate excretion.