Table 4.
Effects of phytase dose level on apparent ileal digestibility (AID, %) of AA
| NC+ phytase levels, FTU/kg | Probability of contrast | Dose response model1 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| PC | NC | 250 | 500 | 1,000 | 2,000 | SEM | PC vs NC | NC vs phytase | Linear | Exponential | |
| Cysteine | 61.5 | 62.3 | 67.2 | 68.3 | 70.8 | 71.1 | 2.09 | 0.3363 | 0.0001 | 0.015 | 0.163# |
| Isoleucine | 80.1 | 78.5 | 79.8 | 82.3 | 83.2 | 85.3 | 1.15 | 0.4152 | 0.0091 | <0.001 | 0.191# |
| Leucine | 80.6 | 79 | 80.5 | 83 | 84.2 | 85.1 | 1.2 | 0.3966 | 0.0068 | <0.001 | 0.129# |
| Lysine | 84.2 | 81.6 | 84 | 86.7 | 87.3 | 88.6 | 1.49 | 0.1245 | 0.0007 | <0.001 | 0.051# |
| Methionine | 81.7 | 80.5 | 81.6 | 84.5 | 83.7 | 85.7 | 3.26 | 0.3334 | 0.0395 | 0.059# | 0.546 |
| Threonine | 77.2 | 76.7 | 79.4 | 82.3 | 82 | 83.3 | 1.37 | 0.7704 | 0.0005 | 0.001 | 0.056# |
| Tryptophan | 78.9 | 78.9 | 79.5 | 84.1 | 83.4 | 82 | 3.12 | 0.9805 | 0.0836 | 0.228 | 0.375 |
| Valine | 76.6 | 75.3 | 77.2 | 78.6 | 80.8 | 82.4 | 1.98 | 0.5606 | 0.0169 | <0.001 | 0.29# |
| Mean | 77.6 | 76.6 | 78.7 | 81.2 | 81.9 | 82.9 | 1.84 | 0.3414 | 0.0012 | <0.001 | 0.072# |
NC, negative control; PC, positive control.
1Linear and exponential regression analysis were performed with increasing phytase dose from 0 (NC) to 2,000 FTU/kg, excluding PC, using JMP fit Y by X (linear response, where P-value is for phytase dose) and modeling-nonlinear - exponential growth and decay: fit exponential 3P (exponential response = a+b * EXP (c * phytase dose)). The P-value in the table is for growth rate. When P-value is below <0.1 for one of the models, a goodness of fit test was done, and the optimal model is the prediction equation with the lowest AIC (measure of fit) and root mean square error (RMSE, measure of precision) and marked with #.