Minimum phosphorus requirement for Santa Inês lambs reared under tropical conditions

The aim of this study was to determine endogenous fecal loss and phosphorus absorption, as well as to estimate minimum phosphorus requirement for Santa Inês lambs supplemented with different levels of dicalcium phosphate. Twelve male non-castrated Santa Inês sheep, weighing 22.6 ± 2.21 kg, received a basal diet containing Coast cross hay offered ad libitum, 200 g/day cassava meal, 15 g/day urea and 10 g/day mineral mixture to meet their maintenance requirements. The treatments consisted of adding dicalcium phosphate to the basal diet to give 1.5, 3.0 and 4.5 g of phosphorus/animal/day. On the 22nd day of the experiment, 7.4 MBq of 32P was injected through the jugular vein of each animal. Samples of blood, faeces and urine were collected for a 7-days period and specific activities were determined. There was a significant regression between phosphorus absorption, total phosphorus excreted in faeces, endogenous faecal loss and retention with phosphorus intake. For zero retention, the phosphorus intake was 140.86 mg/kg live weight, resulting a minimum requirement of 3.18 g/day/animal of phosphorus and close to that recommended for wool lambs.