Abstract
Summary Growing wether sheep in metabolism cages were fed a low phosphorus diet (0–7 g P/day) and providing 16 g N/day supplemented with either urea phosphate, monoammonium phosphate or dicalcium phosphate and with appropriate additions of urea to give equivalent additional intakes of phosphorus (1–75 g P/day) and nitrogen (4–6 g N/day). All three sources of phosphorus and nitrogen resulted in similar and significantly improved phosphorus and nitrogen retentions. There were also very similar effects on urine outputs of phosphorus and nitrogen and on the concentrations of phosphorus and urea in the blood of the sheep.