Table 8.

Results of linear regressions of ileal or excreta P outputs on total dietary P content in Experiment 2.

Item	Regression equation1	SE2 of the slope	SE2 of the intercept	R2	Digestibility/retention coefficient
Soybean meal
True ileal P digestibility	Y = 0.167X + 0.086	0.03	0.07	0.69	0.833
True excreta P retention	Y = 0.486X + 0.024	0.05	0.10	0.89	0.514
Spray-dried plasma protein
True ileal P digestibility	Y = 0.024X + 0.077	0.02	0.04	0.08	0.976
True excreta P retention	Y = 0.013X + 0.173	0.03	0.05	0.02	0.987
Meat and bone meal3
True ileal P digestibility	Y = 0.388X – 0.140	0.06	0.13	0.77	0.612
True excreta P retention	Y = 0.675X – 0.018	0.05	0.12	0.93	0.325
Meat and bone meal4
True ileal P digestibility	Y = 0.767X + 1.778	0.05	0.22	0.94	0.233
True excreta P retention	Y = 0.473X – 0.378	0.05	0.20	0.88	0.527

¹Regression of ileal digesta or excreta P output (g/kg dry matter intake) on dietary P content (g/kg) determined by feeding diets containing graded levels of either soybean meal, spray-dried plasma protein, or meat and bone meal. The slope represents true P indigestibility. The digestibility and excreta retention coefficients were calculated by subtracting the slope values from one.

²Abbreviation: SE = Standard error.

³Determined using diets 7 to 9 in Table 1 where the MBM was the only source of dietary P.

⁴Determined using diets 10 to 12 in Table 1 where the MBM was added to a corn–soybean meal–potato protein diet.