Evaluation of the broiler's ability to adapt to an early moderate deficiency of phosphorus and calcium.

We studied the ability of broiler chickens to adapt to early moderate P and Ca deficiencies by evaluating the impact of feeding different concentrations of P and Ca, from 1 to 18 d, on performance, bone characteristics, and nutrient absorption in the grower (Gr) period (18 to 32 d). Two starter (St) diets were fed from 1 to 18 d: a control (C) diet [0.45% nonphytate P (nPP) and 0.9% Ca] and a low (L) diet (0.30% nPP and 0.6% Ca). On d 19, half of the birds fed the St C diet were switched to a Gr C diet (0.40% nPP and 0.8% Ca), and the other half were switched to a Gr L diet (0.30% nPP and 0.6% Ca), whereas those fed the L diet in the St phase were fed the L diet in the Gr phase, resulting in a total of 3 treatments. Broiler chickens fed the St L diet weighed less (P < 0.05) than those fed the St C diet at 18 d; however, by 23 d they had they caught up to the C-C birds, and no BW differences (P > 0.05) were observed at 28 and 32 d. Feeding the St L diet resulted in decreased (P < 0.05) tibia ash at 18 d, but by 32 d their tibia ash was not different from that of birds fed the St C and Gr L diets. Broilers subjected to P and Ca restriction from hatch to 18 d absorbed more P and Ca during all times sampled than birds fed the St C and Gr C diets or those fed the St C and the Gr L diet. These results demonstrated that modern broilers exhibited a high adaptive capacity when they were exposed to early dietary P or Ca restrictions.