Meta-analysis of phosphorus balance data from growing pigs

M. Schulin-Zeuthen, E. Kebreab, W.J.J. Gerrits, S. Lopez, M.Z. Fan, R.S. Dias, J. France

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21 Citations (Scopus)


Many studies have highlighted concerns over current methods of determining endogenous P losses and P requirements in growing pigs. Therefore, a database containing observations on 350 pigs was assembled from various studies. Four functions for analyzing P balance data were considered: 1) a straight line, 2) a diminishing returns function (monomolecular), 3) a sigmoidal function with a fixed point of inflection (Gompertz), and 4) a sigmoidal function with a flexible point of inflection (Richards). The nonlinear functions were specifically reparameterized to assign biological meaning to the parameters. Meta-analysis of the data was conducted to estimate endogenous P excretion, maintenance requirement, and efficiency of utilization. Phosphorus retention was regressed against either available P intake or total P intake [all variables scaled by metabolic BW (BW0.75)]. There was evidence of non-linearity in the data, and the monomolecular function provided the best fit to the data. The Richards equation did not fit the data well and appeared overparameterized. Estimates of endogenous P excretion of 14 and 17 mg/kg of BW0.75 · d based on available and total P analysis, respectively, were predicted by the monomolecular equation, which were within the range reported in the literature. Maintenance requirement values of 15 mg of available P/kg of BW0.75 · d and 37 mg of total P/kg of BW0.75· d were obtained, based on the monomolecular equation. Average efficiencies of conversion of dietary P to retained P were 65 and 36% for available and total P, respectively, with greater efficiency values calculated for low P intakes. Although the monomolecular equation fitted the data best, more observations at high P intakes/kg of BW0.75 are required to determine conclusively whether P retention scaled by metabolic BW is linearly related to available or total P intake.
Original languageEnglish
Pages (from-to)1953-1961
JournalJournal of Animal Science
Issue number8
Publication statusPublished - 2007


  • finishing pigs
  • nutrient utilization
  • digestibility
  • corn
  • methodology
  • environment
  • calcium
  • phytase
  • outputs
  • losses


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