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. 2018 Nov 16;97(2):698–713. doi: 10.1093/jas/sky441

Figure 2.

Figure 2.

Predicted effect of phytase dose and digestible lysine requirement on feed conversion ratio of broilers from hatch to 42 d posthatch (Exp. 1). The model was determined as: !y = 3.7748– 0.0431!x + 0.0002!x2 – 3.5667e-5!v+ 7.7502e-9!v2.R2 = 0.69. P < 0.0001. Diets were formulated to contain digestible lysine at ● 80%, ■ 88%, ▲ 96%, or × 104% of the requirement according to Cobb 400 breed guidelines (VenCobb 400 Broiler Management Guide, Cobb-Vantress Inc., Siloam Spring, AR); this corresponds to 1.02, 1.13, 1.23, and 1.33% dgLys, respectively, in the starter diets and 0.84, 0.92, 1.01, and 1.09% dgLys, respectively, in the grower diets. The digestible lysine concentration to maximize (reduce) feed conversion ratio was predicted at 98.9% of the requirement (1.24% dgLys in the starter diet and 1.04% dgLys in the grower diet), regardless of the dose of phytase supplied in the diet. The dose of phytase to minimize feed conversion ratio was predicted at 2,308 FTU/kg of diet, regardless of the digestible lysine concentration of the diet.