Blood phosphorus levels of laying hens at various time intervals after dosing with phosphoric acid

Two experiments were conducted to study the pattern of change in serum inorganic phosphorus level in laying hens fed a diet containing 0.30% total phosphorus after dosing with a known amount of phosphorus. Serum phosphorus level of undosed hens was 2.5 mg/100 ml at oviposition in both experiments. After dosing with 100 mg of phosphorus in 10 ml of a phosphoric acid solution, serum phosphorus level increased sharply and reached a peak of about 7.0 mg/100 ml between 30 and 60 minutes in experiment 2. After the peak the elevated level of serum phosphorus decreased logarithmically until 5 to 6 hours after dosing and eventually decreased to 2.5 mg/100 ml which was the serum phosphorus level of undosed hens in experiment 1. The half-life of the elevated portion of serum phosphorus due to the dosing was about 100 minutes.