Table 3. Effect of different content on protein intake and nitrogen utilization of male Pekin ducks for 21 days after hatching1)
Item | Dietary protein content (%) | SEM | p-value |
15 | 17 | 19 | 21 | 23 | 25 |
Protein intake (g) |
Day 7 | 5.55e | 6.49d | 7.69c | 8.09b | 9.04a | 9.36a | 0.202 | 0.001 |
Day 14 | 14.63f | 16.34e | 19.28d | 20.20c | 21.83b | 24.83a | 0.498 | 0.001 |
Day 21 | 22.29f | 25.70e | 28.91d | 30.96c | 34.24b | 35.77a | 0.703 | 0.001 |
Day 1–21 | 14.16f | 16.18e | 18.63d | 19.75c | 21.71b | 23.32a | 0.46 | 0.001 |
Nitrogen retention (g) | | | | | | | | |
Day 1–21 | 36.92c | 38.50b | 39.87a | 40.87a | 40.57a | 39.84a | 0.258 | 0.001 |
Nitrogen excretion (g) |
Day 1–21 | 10.65f | 15.85e | 22.72d | 25.49c | 32.36b | 38.52a | 1.383 | 0.001 |
Each value is the mean of 6 replicates (12 birds per cage).
Means in the same row with different superscripts differ in the level of crude protein content (p < 0.05).