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. 2020 Jul 28;99(8):3921–3929. doi: 10.3382/ps/pez006

Figure 3.

Figure 3

Tibial breaking strength (kgf) of broiler breeder hens fed diets supplemented with Fe. Regression equations obtained using the increasing dietary Fe in the current study (44, 58, 72, 86, and 100 mg/kg). Dashed line is the quadratic polynomial (QP) regression (Y = 2.68 + 0.725 × X − 0.00469 × X2; the maximum response arrow pointing at 77.4 mg/kg Fe, R2 = 0.229, P = 0.002); solid line is the 2-slope broken-line estimation [Y = 20.0 + 0.139 × X (X ≤ 89.0) and Y = 71.5 − 0.439 × X (X > 89.0), the maximum response at 89.0 mg/kg Fe, R2 = 0.294, P < 0.001].