Results of an international phosphorus digestibility ring test with broiler chickens

Abstract

The objective of this ring test was to investigate the prececal phosphorus (P) digestibility of soybean meal (SBM) in broiler chickens using the trial protocol proposed by the World's Poultry Science Association. It was hypothesized that prececal P digestibility of SBM determined in the collaborating stations is similar. Three diets with different inclusion levels of SBM were mixed in a feed mill specialized in experimental diets and transported to 17 collaborating stations. Broiler chicks were raised on commercial starter diets according to station-specific management routine. Then they were fed the experimental diets for a minimum of 5 d before content of the posterior half of the ileum was collected. A minimum of 6 experimental replicates per diet was used in each station. All diets and digesta samples were analyzed in the same laboratory. Diet, station, and their interaction significantly affected (P < 0.05) the prececal digestibility values of P and calcium of the diets. The prececal P digestibility of SBM was determined by linear regression and varied among stations from 19 to 51%, with significant differences among stations. In a subset of 4 stations, the prececal disappearance of myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate)-P; InsP6-P) also was studied. The prececal InsP6-P disappearance correlated well with the prececal P digestibility. We hypothesized that factors influencing InsP6 hydrolysis were main contributors to the variation in prececal P digestibility among stations. These factors were probably related to the feeding and housing conditions (floor pens or cages) of the birds in the pre-experimental phase. Therefore, we suggest that the World's Poultry Science Association protocol for the determination of digestible P be should extended to the standardization of the pre-experimental period. We also suggest that comparisons of P digestibility measurements among studies are made only with great caution until the protocol is more refined.

Phytate degradation and phosphorus digestibility in broilers and turkeys fed different corn sources with or without added phytase

“…Phytate-degrading bacteria with high in vitro phytase activity have been isolated from the upper GIT of chickens (Palacios et al, 2008). Nevertheless, data suggest that the amount of InsP 6 that can be prececally hydrolyzed in broilers fed corn-SBM-based diets is limited, thus confirming the results reported by Rodehutscord et al (2017). The short retention time of digesta in the pc digestive tract may also limit the degradation of InsP 6 from high-phytate diets.…”

Effect of supplemental phytase and xylanase in wheat-based diets on prececal phosphorus digestibility and phytate degradation in young turkeys

“…The decreased pc InsP 6 disappearance in the non-supplemented GD with increased concentrations of InsP 6 underlines the limited capacity of animals to hydrolyze InsP 6 , as was previously shown in broilers fed corn-SBM-based diets (Rodehutscord et al, 2017 ) and as we also observed in turkeys (unpublished). Moreover, these differences between BD and GD confirm that intrinsic phytase activity in wheat has only a minor role with respect to the degradation of InsP 6 .…”

Phytase supplementation effects on amino acid digestibility depend on the protein source in the diet but are not related to InsP6 degradation in broiler chickens

“…One possible reason is an upper limit of InsP 6 degradation capacity. An upper level of pc InsP 6 degradation was indicated in the P digestibility ring test ( Rodehutscord et al, 2017b ). However, the ring test was conducted using diets without phytase supplementation.…”