Responses of growing poultry to phosphorus supply

Abstract

Excessive levels of Phosphorus (P) in poultry feeds is environmentally unfriendly and costly. A meta-analysis was performed to propose poultry responses to P supply. Sixty two publications with 1271 observations in broilers, turkeys and ducks were collected. Optimal values for Daily Body Weight Gain and Feed Conversion Ratio varied from 6 to 7 g of total P by kg of diet, with a Ca/P ratio ranging from 1.4 to 1.6. Higher values were obtained for turkeys. P apparent retention decreased with total P in the diet and increased with microbial phytase supply, thanks to phytic P improved availability. This increased P retention leads to lower P excretion in the environment. Furthermore, P and microbial phytase supplies increased bone mineralization with an optimal average P intake of 250 to 300 mg/d for 0-3 weeks-old broilers. The present study was performed on total P in the diet. However, feeds are usually formulated on available P basis. Therefore, the following step of this work will be to translate the obtained results and equations into available P by including additional effects of feedstuffs, phytases, Ca/P ratio, Vitamin D. Moreover, this work underlines that if numerous data are available for young broilers, few are for turkeys and ducks especially during the finishing periods, for which further research might bring foreseeable improvements.