Comparative studies with three-week-old chickens, turkeys, ducks, and quails on the response in phosphorus...

We studied whether the availability of P is different among poultry species. A basal diet was mixed mainly based on corn, potato protein, and dried egg white. It was calculated according to the recommendations for young turkeys with the exception of P and Ca concentrations, which were deficient. Monobasic calcium phosphate (MCP) was added in graded levels, and analyzed P concentrations in the 7 diets were (in g/kg of dry matter) 2.9, 3.7, 4.5, 5.3, 6.2, 7.2, and 7.7. Four experiments were conducted with 3-wk-old broiler chickens, turkeys, ducks, and quails. Birds were kept in balance crates, and 8 individuals were allocated to each treatment diet. Birds were fed the treatment diets for 10 d, and excreta were quantitatively collected during the last 5 d. P utilization was calculated as the proportion of P intake that was accreted by the birds. The P accretion response of birds to incremental MCP intake was described with sigmoidal functions, and the marginal efficiency of P utilization ((delta)y/(delta)x) was calculated. Utilization of P from the unsupplemented basal diet was 58% in broilers, 55% in quails, 46% in ducks, and 39% in turkeys. Supplementation of MCP significantly increased P accretion in all species. Ninety-five percent of the estimated ymax in P accretion was achieved with 8.4, 7.3, and 4.8 g P/kg of dietary DM in broilers, ducks, and quails. No plateau in P accretion was achieved in turkeys. These differences correlate well with the differences in the feed/gain ratio, which was 1.3 in turkeys, 1.7 in broilers, 1.9 in ducks, and 3.5 in quails. The maximum in marginal efficiency of supplemented P was 96% in ducks, 81% in turkeys, 74% in broilers, and 77% in quails. These maxima were achieved at different levels of MCP supplementation. We concluded that differences in P availability exist between poultry species for plant and mineral P sources. Quails can be used as model species for broilers in P availability studies, but dietary P levels need special adjustment.