Long-Term Effects of Early Low-Phosphorous Nutritional Conditioning on Broiler Chicken Performance, Bone Mineralization, and Gut Health Under Adequate or Phosphorous-Deficient Diets.

Simple Summary: Phosphorus is a very important nutrient in poultry feeding, and it is involved in many vital metabolic functions and is also a constituent of bones. Despite this, poultry diets have a very low phosphorous availability, which is commonly compensated with the dietary supplementation with inorganic sources of phosphorous and phytases. This study investigated nutritional conditioning with low-phosphorous diets during the first week of life as a strategy to improve the efficiency of phosphorous utilization in broiler chickens. No effect of conditioning on the overall performance was observed, despite evidence for reduced phosphorous excretion, increased duodenal gene expression for phosphorous transporter SLC34A2, and improved phosphorous digestibility and tibia mineralization. It is concluded that phosphorous nutritional conditioning in early life has the potential to increase the dietary phosphorous utilization in poultry, although additional research is required to optimize the duration and extent of the conditioning protocol, as well as to quantify to which extent the dietary supplementation with inorganic phosphorous could be reduced with this strategy. Phosphorous is essential for many metabolic functions and the constitution of bones. Poultry have limited ability to use phosphorous from diets, which is mainly excreted and causes environmental concern. For this reason, diets are commonly supplemented with inorganic phosphorus and phytases. It has been suggested that chickens can adapt to an early nutrient restriction by increasing its efficiency of utilization, an adaptation that has been defined as nutritional conditioning. The aim of this study was to investigate a strategy of phosphorous nutritional conditioning by feeding low phosphorous diets during the first week of life as a strategy to improve the efficiency of phosphorous utilization later in life. To test this, 600 male broiler chickens were fed either a standard (control group) or a phosphorous-deficient diet (conditioned group) during the first week of life. Later in life, the effect of conditioning was tested using standard or P-deficient diets during the finishing phase (21–43 d). Conditioning did not affect overall performance, despite finding evidence for reduced relative phosphorous excretion between days 19 to 21, increased duodenal gene expression for the phosphorous transporter SLC34A2 at day 30 (−6% and +17%, respectively), and tendencies for improved phosphorous digestibility (+7%) and tibia mineralization (+6%) at the end of the trial. It is concluded that phosphorous nutritional conditioning early in life can increase subsequent dietary phosphorous utilization and bone mineralization in poultry, although it may not be able to counteract severe phosphorous deficiencies. Further research is required to assess the extent to which phosphorous supplementation in post-conditioning diets may be reduced with this strategy without compromising performance. [ABSTRACT FROM AUTHOR]